Country：Japan

Publishing type：Research paper (scientific journal)   International / domestic magazine：International journal  

BACKGROUND: For delivering high radiation doses to pancreatic tumors, organ motion management is indispensable; however, studies on this are limited. We aimed to evaluate the efficacy and safety of dynamic tumor tracking (DTT) moderately hypofractionated intensity-modulated radiotherapy (IMRT) in patients with locally advanced pancreatic cancer (LAPC). METHODS: Patients with histological confirmation for LAPC were included. A linac system, which was mounted with a gimbal function, was used for DTT-IMRT. The prescribed dose was 48 Gy in 15 fractions. The primary endpoint was the 1-year rate of freedom from locoregional progression (FFLP). RESULTS: DTT-IMRT was successfully administered in 25 patients enrolled from four institutions. The median range of respiratory motion during DTT-IMRT was 9.8 mm (range: 3.5-27.3 mm), and the median tracking accuracy was 2.6 mm (range: 0.7-5.2 mm). With a median follow-up period of 13.9 months, the 1-year FFLP rate was 75.3% (lower limit of one-sided 80% confidence interval [CI]: 60.2%), which satisfied the predetermined primary endpoint. One-year locoregional progression-free survival, progression-free survival, and overall survival were 56.0% (95% CI: 34.8%-72.7%), 44.0% (95% CI: 24.5%-61.9%), and 60.0% (95% CI: 38.4%-76.1%), respectively. Regarding nonhematologic toxicities, grade 3 acute gastrointestinal (GI) toxicity was observed in two patients (8%), and two patients (8%) each experienced grade 3 late GI and non-GI toxicities. No grade 4 or 5 nonhematologic toxicities were observed. CONCLUSIONS: DTT moderately hypofractionated IMRT shows preferable locoregional control without significant toxicity in patients with LAPC. TRIAL REGISTRATION: UMIN000017521.

DOI： 10.1002/cam4.70648

PubMed

Publishing type：Research paper (scientific journal)   International / domestic magazine：International journal  

BACKGROUND AND PURPOSE: Tumors and fiducial markers do not always exhibit synchronous motion across different respiratory phases, in a phenomenon called the target localization error (TLE). We determined the margin to compensate for the TLE using four-dimensional computed tomography (4D-CT). MATERIALS AND METHODS: We analyzed data from 21 lung tumor patients with fiducial markers; 11 for TLE determination and 10 for validation. Shifted CT images were generated by aligning the centroids of the fiducial markers in the reference phase of 4D-CT with those in each respiratory phase, and the union of gross tumor volumes (GTVs) was determined ( G T V u n i o n s h i f t ). Conversely, variations in GTV centroids across the respiratory phases were calculated, and the 95th percentile of the root mean square error was defined as the TLE. Using this TLE, a GTV with an added TLE ( G T V T L E r e f ) was generated in the reference phase. Subsequently, a treatment plan assuming dynamic tumor tracking (DTT) was created for the planning target volume, derived by adding an isotropic 5 mm margin to G T V T L E r e f , and the dose coverage for G T V u n i o n s h i f t was evaluated. RESULTS: The TLEs (standard deviations of the root mean square error) were 2.0 (0.8) mm, 2.1(0.7) mm, and 3.2 (1.1) mm in the left - right, anterior - posterior, and superior - inferior directions, respectively. A dosimetric evaluation revealed that G T V u n i o n s h i f t did not receive 100 % of the prescribed dose in four of 10 cases owing to artifacts. CONCLUSION: The TLE can be compensated by adding an anisotropic margin to the GTV in the reference phase, a critical consideration in DTT.

DOI： 10.1016/j.phro.2025.100728

PubMed

DOI： 10.18888/rp.0000002745

CiNii Research

＜文献概要＞強度変調放射線治療(intensity-modulated radiation therapy:IMRT)や定位放射線治療,画像誘導放射線治療(image-guided radiotherapy:IGRT)など高精度放射線治療技術の進歩により,空間的に理想的な放射線を照射する精度は革新的に向上した。一方で,治療期間中の標的およびリスク臓器の体積変化や変形といった非剛体性変化への対応は困難なため,計画時の理想的な線量分布と患者体内に投与される線量分布には乖離が生じることになる。

J-GLOBAL

市販のオンライン適応放射線治療(oART)システムを導入した国内医療施設に対し、oARTの現状に関するアンケート調査を実施した。2023年10月までの期間内に、市販のoARTシステム導入済み医療施設に対し、ウェブ上でアンケート調査を行った結果、MRIdian、UnityおよびEthosシステム導入済みの各3施設、計9施設から回答が得られた。だが、MRIdianシステム導入済みの1施設では、回答期限までにoARTは施行されておらず、各施設のoARTシステム台数は1台のみであった。また、MRIdianおよびUnityシステムでは寡分割照射、Ethosシステムでは中等度寡分割や通常分割照射が用いられており、oARTに要する時間はEthosシステムが最も短かった。なお、全施設でoART用のスタッフが追加雇用されており、トレーニングも実施されていたが、コミッショニング期間はベンダーからのビームデータ提供のため、oARTシステム間で異なり、コミッショニング測定時に用いられたチャンバも施設間で異なっていた。本調査結果から、oARTシステム導入に際し有用な情報が得られた。

Publishing type：Research paper (scientific journal)   International / domestic magazine：Domestic journal  

In this study, we aimed to conduct a survey on the current clinical practice of, staffing for, commissioning of, and staff training for online adaptive radiotherapy (oART) in the institutions that installed commercial oART systems in Japan, and to share the information with institutions that will implement oART systems in future. A web-based questionnaire, containing 107 questions, was distributed to nine institutions in Japan. Data were collected from November to December 2023. Three institutions each with the MRIdian (ViewRay, Oakwood Village, OH, USA), Unity (Elekta AB, Stockholm, Sweden), and Ethos (Varian Medical Systems, Palo Alto, CA, USA) systems completed the questionnaire. One institution (MRIdian) had not performed oART by the response deadline. Each institution had installed only one oART system. Hypofractionation, and moderate hypofractionation or conventional fractionation were employed in the MRIdian/Unity and Ethos systems, respectively. The elapsed time for the oART process was faster with the Ethos than with the other systems. All institutions added additional staff for oART. Commissioning periods differed among the oART systems owing to provision of beam data from the vendors. Chambers used during commissioning measurements differed among the institutions. Institutional training was provided by all nine institutions. To the best of our knowledge, this was the first survey about oART performed using commercial systems in Japan. We believe that this study will provide useful information to institutions that installed, are installing, or are planning to install oART systems.

DOI： 10.1007/s12194-024-00828-4

PubMed

大阪公立大学(旧:大阪市立大学)医学部附属病院は、高磁場・高分解能1.5T MRI装置と高精度リニアックが一体化した次世代型放射線治療装置「MRリニアックシステム」を西日本で初導入し、2022年より臨床応用を開始した。大阪府がん拠点病院としてより質の高い特色のあるがん診療を推進すべく、個別化医療を見据えた即時適応放射線治療を展開している。(著者抄録)

Publishing type：Research paper (scientific journal)  

DOI： 10.1016/j.jtho.2023.09.1096

Publishing type：Research paper (scientific journal)   International / domestic magazine：International journal  

BACKGROUND: Both geometric and dosimetric components are commonly considered when determining the margin for planning target volume (PTV). As dose distribution is shaped by controlling beam aperture in peripheral dose prescription and dose-escalated simultaneously integrated boost techniques, adjusting the margin by incorporating the variable dosimetric component into the PTV margin is inappropriate; therefore, geometric components should be accurately estimated for margin calculations. PURPOSE: We introduced an asymmetric margin-calculation theory using the guide to the expression of uncertainty in measurement (GUM) and intra-fractional motion. The margins in fiducial marker-based real-time tumor tracking (RTTT) for lung, liver, and pancreatic cancers were calculated and were then evaluated using Monte Carlo (MC) simulations. METHODS: A total of 74 705, 73 235, and 164 968 sets of intra- and inter-fractional positional data were analyzed for 48 lung, 48 liver, and 25 pancreatic cancer patients, respectively, in RTTT clinical trials. The 2.5th and 97.5th percentiles of the positional error were considered representative values of each fraction of the disease site. The population-based statistics of the probability distributions of these representative positional errors (PD-RPEs) were calculated in six directions. A margin covering 95% of the population was calculated using the proposed formula. The content rate in which the clinical target volume (CTV) was included in the PTV was calculated through MC simulations using the PD-RPEs. RESULTS: The margins required for RTTT were at most 6.2, 4.6, and 3.9 mm for lung, liver, and pancreatic cancer, respectively. MC simulations revealed that the median content rates using the proposed margins satisfied 95% for lung and liver cancers and 93% for pancreatic cancer, closer to the expected rates than the margins according to van Herk's formula. CONCLUSIONS: Our proposed formula based on the GUM and motion probability distributions (MPD) accurately calculated the practical margin size for fiducial marker-based RTTT. This was verified through MC simulations.

DOI： 10.1002/mp.16614

PubMed

Publishing type：Research paper (scientific journal)   International / domestic magazine：International journal  

DOI： 10.1186/s13014-023-02276-7

PubMed

Publishing type：Research paper (scientific journal)  

DOI： 10.1016/s0167-8140(23)09047-3

Publishing type：Research paper (scientific journal)   International / domestic magazine：International journal  

PURPOSE: The feasibility of a deep learning-based markerless real-time tumor tracking (RTTT) method was retrospectively studied with orthogonal kV X-ray images and clinical tracking records acquired during lung cancer treatment. METHODS: Ten patients with lung cancer treated with marker-implanted RTTT were included. The prescription dose was 50 Gy in four fractions, using seven- to nine-port non-coplanar static beams. This corresponds to 14-18 X-ray tube angles for an orthogonal X-ray imaging system rotating with the gantry. All patients underwent 10 respiratory phases four-dimensional computed tomography. After a data augmentation approach, for each X-ray tube angle of a patient, 2250 digitally reconstructed radiograph (DRR) images with gross tumor volume (GTV) contour labeled were obtained. These images were adopted to train the patient and X-ray tube angle-specific GTV contour prediction model. During the testing, the model trained with DRR images predicted GTV contour on X-ray projection images acquired during treatment. The predicted three-dimensional (3D) positions of the GTV were calculated based on the centroids of the contours in the orthogonal images. The 3D positions of GTV determined by the marker-implanted RTTT during the treatment were considered as the ground truth. The 3D deviations between the prediction and the ground truth were calculated to evaluate the performance of the model. RESULTS: The median GTV volume and motion range were 7.42 (range, 1.18-25.74) cm3 and 22 (range, 11-28) mm, respectively. In total, 8993 3D position comparisons were included. The mean calculation time was 85 ms per image. The overall median value of the 3D deviation was 2.27 (interquartile range: 1.66-2.95) mm. The probability of the 3D deviation smaller than 5 mm was 93.6%. CONCLUSIONS: The evaluation results and calculation efficiency show the proposed deep learning-based markerless RTTT method may be feasible for patients with lung cancer.

DOI： 10.1002/acm2.13894

PubMed

CiNii Research

Publishing type：Research paper (scientific journal)   International / domestic magazine：International journal  

The information of definitive radiotherapy for a pregnant woman with malignancy was limited; however, it was reported to be potentially feasible with minimal risks. We performed definitive chemoradiotherapy for a pregnant woman with locally advanced cervical esophageal cancer. Feasibility of radiotherapy and safety of fetus were confirmed by the phantom study estimating fetal dose, and monitoring it in each radiotherapy session. The planned chemoradiotherapy completely eradicated esophageal cancer while preserving her laryngopharyngeal function. A female infant was delivered by cesarian section after planned chemoradiotherapy, and she grew without any apparent disorders 2 years after chemoradiotherapy. Chemoradiotherapy might be one of the treatment options for a pregnant woman with cervical esophageal cancer especially wishing the preservation of laryngopharyngeal function.

DOI： 10.1007/s13691-022-00564-9

PubMed

症例は38歳女性で、3妊0産であった。妊娠11週目に2ヵ月間持続する痛みのない左頸部リンパ節腫脹を呈した。当院に紹介され、18F-FDG PET/CTにより頸部食道に18F-FDGの単一異常集積を認めた。生検を伴う食道胃十二指腸内視鏡検査で頸部食道入口に扁平上皮癌の組織型を有する突出した腫瘍を検出した。妊娠19週で下咽頭浸潤を伴う局所進行頸部食道癌(ycT2N1M1、左頸部リンパ節転移)と診断した。実治療の放射線治療計画を用いたファントム試験に基づき、妊娠23週から放射線治療66Gy/33分割+シスプラチン80mg/m2/dayの3週間投与で化学放射線治療を開始し、妊娠30週まで中断することなく完遂した。妊娠34週の内視鏡検査で食道原発癌に対する奏功が示唆された。その後、抗癌剤治療の追加を中止した。治療期間中、グレード4の急性血液学的有害事象は認めなかった。グレード2以上の急性非血液性有害事象はグレード2の食道炎のみであった。化学放射線療法中に胎児発育遅延は認めなかったが、分娩が正常に進行せず、妊娠41週(化学放射線療法後18週目)に帝王切開を行った。新生児は3284g女児で、呼吸促迫のため新生児集中治療室に入院したが回復し、翌日新生児集中治療室から退院した。化学放射線療法施行5ヵ月後に頸部食道癌の完全寛解を確認した。2年後にも再発はなかった。

DOI： 10.7759/cureus.26217

PubMed

Publishing type：Research paper (scientific journal)   International / domestic magazine：International journal  

BACKGROUND AND PURPOSE: This study aimed to evaluate the safety and efficacy of dynamic tumor tracking-stereotactic body radiotherapy (DTT-SBRT) for lung tumors. MATERIALS AND METHODS: Patients with cStage I primary lung cancer or metastatic lung cancer with an expected range of respiratory motion of ≥10 mm were eligible for the study. The prescribed dose was 50 Gy in four fractions. A gimbal-mounted linac was used for DTT-SBRT delivery. The primary endpoint was local control at 2 years. RESULTS: Forty-eight patients from four institutions were enrolled in this study. Forty-two patients had primary non-small-cell lung cancer, and six had metastatic lung tumors. DTT-SBRT was delivered for 47 lesions in 47 patients with a median treatment time of 28 min per fraction. The median respiratory motion during the treatment was 13.7 mm (range: 4.5-28.1 mm). The motion-encompassing method was applied for the one remaining patient due to the poor correlation between the abdominal wall and tumor movement. The median follow-up period was 32.3 months, and the local control at 2 years was 95.2% (lower limit of the one-sided 85% confidence interval [CI]: 90.3%). The overall survival and progression-free survival at 2 years were 79.2% (95% CI: 64.7%-88.2%) and 75.0% (95% CI: 60.2%-85.0%), respectively. Grade 3 toxicity was observed in one patient (2.1%) with radiation pneumonitis. Grade 4 or 5 toxicity was not observed. CONCLUSION: DTT-SBRT achieved excellent local control with low incidences of severe toxicities in lung tumors with respiratory motion.

DOI： 10.1016/j.radonc.2022.04.028

PubMed

肺体幹部定位放射線治療(SBRT)において、線量計算アルゴリズム間のdosiomic特徴量の再現性について検討した。対象患者には2011年3月～2017年12月にかけ、著者等の医療施設で肺SBRTが施行された早期非小細胞肺癌患者105例(男性76例、女性29例)とした。iPlan radiation treatment planning system上でX-ray voxel Monte Carlo(XVMC)を用いて線量計算を行った後、Eclipse RTPS上で、Acuros XB(AXB)とanalytical anisotropic algorithm(AAA)により放射線量を再計算した。その結果、XVMC-AXB、XVMC-AAAおよびAXB-AAAに検出された再現性の高い一次法とテクスチャ特徴量は、それぞれ34.8%、26.9%および31.0%であった。また、ウェーブレットフィルタならびに処方線量のサブグループ解析では、absolute pairwise concordance correlation coefficient平均値の最大差が、0.70と0.11であることが確認された。以上の解析結果から、肺SBRTに対し異なるタイプの線量計算アルゴリズムを用いる場合には、ウェーブレットフィルタをベースとしたdosiomic解析は限定的なものと考えられた。

Publishing type：Research paper (scientific journal)   International / domestic magazine：International journal  

BACKGROUND: In infrared reflective (IR) marker-based hybrid real-time tumor tracking (RTTT), the internal target position is predicted with the positions of IR markers attached on the patient's body surface using a prediction model. In this work, we developed two artificial intelligence (AI)-driven prediction models to improve RTTT radiotherapy, namely, a convolutional neural network (CNN) and an adaptive neuro-fuzzy inference system (ANFIS) model. The models aim to improve the accuracy in predicting three-dimensional tumor motion. METHODS: From patients whose respiration-induced motion of the tumor, indicated by the fiducial markers, exceeded 8 mm, 1079 logfiles of IR marker-based hybrid RTTT (IR Tracking) with the gimbal-head radiotherapy system were acquired and randomly divided into two datasets. All the included patients were breathing freely with more than four external IR markers. The historical dataset for the CNN model contained 1003 logfiles, while the remaining 76 logfiles complemented the evaluation dataset. The logfiles recorded the external IR marker positions at a frequency of 60 Hz and fiducial markers as surrogates for the detected target positions every 80-640 ms for 20-40 s. For each logfile in the evaluation dataset, the prediction models were trained based on the data in the first three quarters of the recording period. In the last quarter, the performance of the patient-specific prediction models was tested and evaluated. The overall performance of the AI-driven prediction models was ranked by the percentage of predicted target position within 2 mm of the detected target position. Moreover, the performance of the AI-driven models was compared to a regression prediction model currently implemented in gimbal-head radiotherapy systems. RESULTS: The percentage of the predicted target position within 2 mm of the detected target position was 95.1%, 92.6% and 85.6% for the CNN, ANFIS, and regression model, respectively. In the evaluation dataset, the CNN, ANFIS, and regression model performed best in 43, 28 and 5 logfiles, respectively. CONCLUSIONS: The proposed AI-driven prediction models outperformed the regression prediction model, and the overall performance of the CNN model was slightly better than that of the ANFIS model on the evaluation dataset.

DOI： 10.1186/s13014-022-02012-7

PubMed

Publishing type：Research paper (scientific journal)   International / domestic magazine：Domestic journal  

To evaluate the reproducibility of dose-based radiomic (dosiomic) features between dose-calculation algorithms for lung stereotactic body radiation therapy (SBRT). We analyzed 105 patients with early-stage non-small cell lung cancer who underwent lung SBRT between March 2011 and December 2017. Radiation doses of 48, 60, and 70 Gy were prescribed to the isocenter in 4-8 fractions. Dose calculations were performed using X-ray voxel Monte Carlo (XVMC) on the iPlan radiation treatment planning system (RTPS). Thereafter, the radiation doses were recalculated using the Acuros XB (AXB) and analytical anisotropic algorithm (AAA) on the Eclipse RTPS while maintaining the XVMC-calculated monitor units and beam arrangements. A total of 6808 dosiomic features were extracted without preprocessing (112 shape, 144 first-order, and 600 texture features) or with wavelet filters to eight decompositions (1152 first-order and 4800 texture features). Features with absolute pairwise concordance correlation coefficients-|CCcon|-values exceeding or equaling 0.85 were considered highly reproducible. Subgroup analyses were performed considering the wavelet filters and prescribed doses. The numbers of highly reproducible first-order and texture features were 34.8%, 26.9%, and 31.0% for the XVMC-AXB, XVMC-AAA, and AXB-AAA pairs, respectively. The maximum difference between the mean |CCcon| values was 0.70 and 0.11 for the subgroup analyses of wavelet filters and prescribed dose, respectively. The application of wavelet filter-based dosiomic analyses may be limited when using different types of dose-calculation algorithms for lung SBRT.

DOI： 10.1007/s12194-022-00651-9

PubMed

Other URL： https://link.springer.com/article/10.1007/s12194-022-00651-9/fulltext.html

Publishing type：Research paper (scientific journal)   International / domestic magazine：International journal  

The irradiated volume of intestines is associated with gastrointestinal toxicity in preoperative chemoradiotherapy for rectal cancer. The current trial prospectively explored how much of the irradiated volume of intestines was reduced by intensity-modulated radiotherapy (IMRT) compared with 3-dimensional conformal radiotherapy (3DCRT) and whether IMRT might alleviate the acute gastrointestinal toxicity in this population. The treatment protocol encompassed preoperative chemoradiotherapy using IMRT plus surgery for patients with clinical T3-4, N0-2 low rectal cancer. IMRT delivered 45 Gy per 25 fractions for gross tumors, mesorectal and lateral lymph nodal regions, and tried to reduce the volume of intestines receiving 15 Gy (V15 Gy) < 120 cc and V45 Gy ≤ 0 cc, respectively, while keeping target coverage. S-1 and irinotecan were concurrently administered. Acute gastrointestinal toxicity, rates of clinical downstaging, sphincter preservation, local regional control (LRC) and overall survival (OS) were evaluated. Twelve enrolled patients completed the chemoradiotherapy protocol. The volumes of intestines receiving medium to high doses were reduced by the current IMRT protocol compared to 3DCRT; however, the predefined constraint of V15 Gy was met only in three patients. The rate of ≥ grade 2 gastrointestinal toxicity excluding anorectal symptoms was 17%. The rates of clinical downstaging, sphincter preservation, three-year LRC and OS were 75%, 92%, 92% and 92%, respectively. In conclusion, preoperative chemoradiotherapy using IMRT for this population might alleviate acute gastrointestinal toxicity, achieving high LRC and sphincter preservation; although further advancement is required to reduce the irradiated volume of intestines, especially those receiving low doses.

DOI： 10.1093/jrr/rrab106

PubMed

Publishing type：Research paper (scientific journal)   International / domestic magazine：International journal  

PURPOSE: For pancreatic cancer patients, image guided radiation therapy and real-time tumor tracking (RTTT) techniques can deliver radiation to the target accurately. Currently, for the radiation therapy machine with kV X-ray imaging systems, internal markers must be implemented to facilitate tumor tracking. The purpose of this study was to develop a markerless deep learning-based pancreatic tumor positioning procedure for real-time tumor tracking with a kV X-ray imaging system. METHODS AND MATERIALS: Fourteen pancreatic cancer patients treated with intensity-modulated radiation therapy from six fixed gantry angles with a gimbal-head radiotherapy system were included in this study. For a gimbal-head radiotherapy system, the three-dimensional (3D) intrafraction target position can be determined using an orthogonal kV X-ray imaging system. All patients underwent four-dimensional computed tomography (4DCT) simulations for treatment planning, which were divided into 10 respiratory phases. After a patient's 4DCT was acquired, for each X-ray tube angle, 10 digitally reconstructed radiograph (DRR) images were obtained. Then, a data augmentation procedure was conducted. The data augmentation procedure first rotated the CT volume around the superior-inferior and anterior-posterior directions from -3° to 3° in 1.5° intervals. Then, the Super-SloMo model was adapted to interpolate 10 frames between respiratory phases. In total, the data augmentation procedure expanded the data scale 250-fold. In this study, for each patient, 12 datasets containing the DRR images from each specific X-ray tube angle based on the radiation therapy plan were obtained. The augmented dataset was randomly divided into training and testing datasets. The training dataset contained 2000 DRR images with clinical target volume (CTV) contours labeled for fine-tuning the pre-trained target contour prediction model. After the fine-tuning, the patient and X-ray tube angle-specific CTV contour prediction model was acquired. The testing dataset contained the remaining 500 images to evaluate the performance of the CTV contour prediction model. The dice similarity coefficient (DSC) between the area enclosed by the CTV contour and predicted contour was calculated to evaluate the model's contour prediction performance. The 3D position of the CTV was calculated based on the centroid of the contour in the orthogonal DRR images, and the 3D error of the prediction position was calculated to evaluate the CTV positioning performance. For each patient, the DSC results from 12 X-ray tube angles and 3D error from 6 gantry angles were calculated, representing the novelty of this study. RESULTS: The mean and standard deviation (SD) of all patients' DSCs were 0.98 and 0.015, respectively. The mean and SD of the 3D error were 0.29 mm and 0.14 mm, respectively. The global maximum 3D error was 1.66 mm, and the global minimum DSC was 0.81. The mean calculation time for CTV contour prediction was 55 ms per image. This fulfills the requirement of RTTT. CONCLUSIONS: Regarding the positioning accuracy and calculation efficiency, the presented procedure can provide a solution for markerless real-time tumor tracking for pancreatic cancer patients.

DOI： 10.1002/mp.15456

PubMed

強度変調放射線治療(IMRT)が三次元原体照射(3DCRT)と比べ、腸管への照射体積をどの程度低減できるか、IMRTにより、急性消化管毒性が軽減されるか、前向きに検討した。TN分類でT3-4、N0-2の下部直腸癌患者12例(男性4例、女性8例、年齢38～69歳)を対象とし、治療プロトコルはIMRTを用いた術前化学放射線療法+外科術とした。IMRTでは腫瘍全体、直腸間膜リンパ節と側方リンパ節に25分割で45Gy処方し、標的へのカバレッジを維持しつつ、腸管への照射体積低減(15Gyで<120cc、45Gyで≦0cc)を試みた。また、化学療法ではS-1とイリノテカン同時投与を行い、急性消化管毒性の発生率、臨床ステージの悪化率、括約筋温存率、局所制御率(LRC)、全生存率(OS)を求めた。その結果、全12例が化学放射線療法を完遂し、3DCRTと比べIMRTでは、中等度～高線量を照射された腸管体積は低減されたが、治療前の15Gyでの規準に合致した患者は、3例のみであった。なお、肛門直腸障害以外に認められた、グレード2以上の消化管毒性発生率は17%で、臨床ステージ悪化率、括約筋温存率、LRC、OSは、それぞれ75%、92%、92%、92%であった。以上より、IMRTを用いた術前化学放射線療法は、消化管毒性を軽減し、高いLRCと括約筋温存が達成されたが、低線量照射による腸管体積への線量低減が、今後の課題として挙げられた。

DOI： 10.22038/IJMP.2021.55707.1923

J-GLOBAL

症例は40歳男性で、1ヵ月前に肛門周囲腫瘤の生検で扁平上皮癌(SCC)が確認され、当院に紹介された。瘻孔関連肛門周囲SCCのcT3N0M0、臨床ステージIIBと診断した。14歳時にクローン病と診断され、栄養療法や免疫抑制剤などの治療を受けてきており、無症状寛解としてコントロールされていた。21歳時には軽度の大腸穿孔により回腸造瘻術を受けていた。患者が肛門機能温存を希望したため化学放射線療法を選択した。化学放射線療法として15MV X線を用いた54Gy/30分割の強度変調回転照射法を施行し、同時にマイトマイシンCと5-フルオロウラシルを投与した。急性血液学的有害事象ではグレード1～3の血球減少、急性非血液学的有害事象ではグレード2の食欲不振、グレード2の下痢、グレード2の放射線皮膚炎、グレード2の肛門痛が認められた。肛門周囲原発腫瘍は化学放射線療法初日から縮小し始め、化学放射線療法最終日には潰瘍を伴って肉眼的腫瘍は消失した。化学放射線療法施行6ヵ月後、肛門周囲腫瘍の完全寛解を確認した。

J-GLOBAL

左側乳癌患者に対する全乳房照射時の深吸気息止め法(DIBH)について、胸式(T-DIBH)と腹式(A-DIBH)とで、リスク臓器(OAR)の線量低減効果の違い、標的とOARの再現性を評価した。全乳房照射を予定している左側乳癌患者14名(年齢中央値49歳)を対象とした。自由呼吸(FB)、T-DIBH、A-DIBHでCTを行い、標的とOARの線量指標を比較した。T-DIBHとA-DIBHでは、それぞれ2枚CTを撮影し、標的と心臓の変位を算出した。その結果、平均心臓線量(MHD)は、T-DIBHとA-DIBHでそれぞれ1.5Gyと1.6Gyであり、FBの2.7Gyよりも有意に低かった(共にp<0.001)。T-DIBHとA-DIBHの間では、MHDに有意差はなかった(p=0.95)が、肺活量の増加率はMHD減少と中程度の相関関係があった(R=0.68)。標的の三次元変位は、T-DIBHでは2.3mm、A-DIBHでは2.0mmであった(p=0.64)。心臓の三次元変位はT-DIBHで1.7mm、A-DIBHで1.8mmであった(p=0.85)。これらの結果から、T-DIBHとA-DIBHの間でMHDと再現性に差がないことが示された。

Publishing type：Research paper (scientific journal)   International / domestic magazine：International journal  

The reports of chemoradiotherapy for anal squamous cell carcinoma with Crohn's disease are few. Severe toxicity related to radiotherapy is concerned in patients with inflammatory bowel disease. We report a case of chemoradiotherapy for locally advanced fistula-related perianal squamous cell carcinoma in a patient with long-standing Crohn's disease which was controlled by a maintenance therapy. The patient completed standard chemoradiotherapy using intensity-modulated radiotherapy without severe toxicity, and achieved complete remission. Standard chemoradiotherapy using intensity-modulated radiotherapy may be feasible and effective treatment for this population when Crohn's disease is controlled.

DOI： 10.1007/s13691-021-00497-9

PubMed

Other URL： https://link.springer.com/article/10.1007/s13691-021-00497-9/fulltext.html

Publishing type：Research paper (scientific journal)   International / domestic magazine：International journal  

PURPOSE: This study aimed to develop a physical geometric phantom for the deformable image registration (DIR) credentialing of radiotherapy centers for a clinical trial and tested the feasibility of the proposed phantom at multiple domestic and international institutions. METHODS AND MATERIALS: The phantom reproduced tumor shrinkage, rectum shape change, and body shrinkage using several physical phantoms with custom inserts. We tested the feasibility of the proposed phantom using 5 DIR patterns at 17 domestic and 2 international institutions (21 datasets). Eight institutions used the MIM software (MIM Software Inc, Cleveland, OH); seven used Velocity (Varian Medical Systems, Palo Alto, CA), and six used RayStation (RaySearch Laboratories, Stockholm, Sweden). The DIR accuracy was evaluated using the Dice similarity coefficient (DSC) and Hausdorff distance (HD). RESULTS: The mean and one standard deviation (SD) values (range) of DSC were 0.909 ± 0.088 (0.434-0.984) and 0.909 ± 0.048 (0.726-0.972) for tumor and rectum proxies, respectively. The mean and one SD values (range) of the HD value were 5.02 ± 3.32 (1.53-20.35) and 5.79 ± 3.47 (1.22-21.48) (mm) for the tumor and rectum proxies, respectively. In three patterns evaluating the DIR accuracy within the entire phantom, 61.9% of the data had more than a DSC of 0.8 in both tumor and rectum proxies. In two patterns evaluating the DIR accuracy by focusing on tumor and rectum proxies, all data had more than a DSC of 0.8 in both tumor and rectum proxies. CONCLUSIONS: The wide range of DIR performance highlights the importance of optimizing the DIR process. Thus, the proposed method has considerable potential as an evaluation tool for DIR credentialing and quality assurance.

DOI： 10.1002/acm2.13319

PubMed

Other URL： https://onlinelibrary.wiley.com/doi/full-xml/10.1002/acm2.13319

Publishing type：Research paper (scientific journal)   International / domestic magazine：International journal  

PURPOSE: This study aimed to assess dosimetric indices of RapidPlan model-based plans for different energies (6, 8, 10, and 15 MV; 6- and 10-MV flattening filter-free), multileaf collimator (MLC) types (Millennium 120, High Definition 120, dual-layer MLC), and disease sites (head and neck, pancreatic, and rectal cancer) and compare these parameters with those of clinical plans. METHODS: RapidPlan models in the Eclipse version 15.6 were used with the data of 28, 42, and 20 patients with head and neck, pancreatic, and rectal cancer, respectively. RapidPlan models of head and neck, pancreatic, and rectal cancer were created for TrueBeam STx (High Definition 120) with 6 MV, TrueBeam STx with 10-MV flattening filter-free, and Clinac iX (Millennium 120) with 15 MV, respectively. The models were used to create volumetric-modulated arc therapy plans for a 10-patient test dataset using all energy and MLC types at all disease sites. The Holm test was used to compare multiple dosimetric indices in different treatment machines and energy types. RESULTS: The dosimetric indices for planning target volume and organs at risk in RapidPlan model-based plans were comparable to those in the clinical plan. Furthermore, no dose difference was observed among the RapidPlan models. The variability among RapidPlan models was consistent regardless of the treatment machines, MLC types, and energy. CONCLUSIONS: Dosimetric indices of RapidPlan model-based plans appear to be comparable to the ones based on clinical plans regardless of energies, MLC types, and disease sites. The results suggest that the RapidPlan model can generate treatment plans independent of the type of treatment machine.

DOI： 10.1002/acm2.13316

PubMed

Publishing type：Research paper (scientific journal)   International / domestic magazine：Domestic journal  

BACKGROUND: The deep inspiration breath hold (DIBH) technique is effective for heart dose reduction in patients with left-sided breast cancer. In deep breathing, some women breathe in thoracic respiration; and others, in abdominal respiration. This study evaluated differences in dose reduction in organs at risk (OAR) and reproducibilities of the target and OAR between thoracic DIBH (T-DIBH) and abdominal DIBH (A-DIBH). METHODS: Fourteen patients with left-sided breast cancer who had planned to receive whole-breast irradiation were included. Computed tomography (CT) was performed in free breathing (FB), T-DIBH, and A-DIBH, and the dosimetric indexes of the target and OAR for three treatment plans were compared. In T-DIBH and A-DIBH, two series CTs were taken in each breathing method and the displacements of the target and heart were calculated. RESULTS: The averaged mean heart doses (MHDs) were 1.5 Gy and 1.6 Gy in T-DIBH and A-DIBH, respectively, significantly lower than 2.7 Gy in FB (p < 0.001 for both breathing methods). Between T-DIBH and A-DIBH, no significant difference in MHD was found (p = 0.95); however, the percentage increase in lung volume positively moderately correlated with the reduction in MHD (R = 0.68). The three-dimensional target displacements were 2.3 mm in T-DIBH and 2.0 mm in A-DIBH (p = 0.64). The three-dimensional heart displacements were 1.7 mm in T-DIBH and 1.8 mm in A-DIBH (p = 0.85). CONCLUSION: The present study demonstrates that the MHD and reproducibility did not differ between T-DIBH and A-DIBH. However, the superior breathing method for increasing lung volume should be determined for each patient.

DOI： 10.1007/s12282-021-01259-4

PubMed

Publishing type：Research paper (scientific journal)   International / domestic magazine：International journal  

PURPOSE: To introduce the concept of statistical shape model (SSM)-based planning organ-at-risk volume (sPRV) for pancreatic cancer patients. METHODS: A total of 120 pancreatic cancer patients were enrolled in this study. After correcting inter-patient variations in the centroid position of the planning target volume (PTV), four different SSMs were constructed by registering a deformable template model to an individual model for the stomach and duodenum. The sPRV, which focused on the following different components of the inter-patient variations, was then created: Scenario A: shape, rotational angle, volume, and centroid position; Scenario B: shape, rotational angle, and volume; Scenario C: shape and rotational angle; and Scenario D: shape. The conventional PRV (cPRV) was created by adding an isotropic margin R (3-15 mm) to the mean shape model. The corresponding sPRV was created from the SSM until the volume difference between the cPRV and sPRV was less than 1%. Thereafter, we computed the overlapping volume between the PTV and cPRV (OLc) or sPRV (OLs) in each patient. OLs being larger than OLc implies that the local shape variations in the corresponding OAR close to the PTV were large. Therefore, OLs/OLc was calculated in each patient for each R-value, and the median value of OLs/OLc was regarded as a surrogate for plan quality for each R-value. RESULTS: For R = 3 and 5 mm, OLs/OLc exceeded 1 for the stomach and duodenum in all scenarios, with a maximum OLs/OLc of 1.21. This indicates that smaller isotropic margins did not sufficiently account for the local shape changes close to the PTV. CONCLUSIONS: Our results indicated that, in contrast to conventional PRV, SSM-based PRVs, which account for local shape changes, would result in better dose sparing for the stomach and duodenum in pancreatic cancer patients.

DOI： 10.1088/1361-6560/abcd1b

PubMed

Publishing type：Research paper (scientific journal)   International / domestic magazine：International journal  

PURPOSE: The purpose of this study was to predict and classify the gamma passing rate (GPR) value by using new features (3D dosiomics features and combined with plan and dosiomics features) together with a machine learning technique for volumetric modulated arc therapy (VMAT) treatment plans. METHODS AND MATERIALS: A total of 888 patients who underwent VMAT were enrolled comprising 1255 treatment plans. Further, 24 plan complexity features and 851 dosiomics features were extracted from the treatment plans. The dataset was randomly split into a training/validation (80%) and test (20%) dataset. The three models for prediction and classification using XGBoost were as follows: (i) plan complexity features-based prediction method (plan model); (ii) 3D dosiomics feature-based prediction model (dosiomics model); (iii) a combination of both the previous models (hybrid model). The prediction performance was evaluated by calculating the mean absolute error (MAE) and the correlation coefficient (CC) between the predicted and measured GPRs. The classification performance was evaluated by calculating the area under curve (AUC) and sensitivity. RESULTS: MAE and CC at γ2%/2 mm in the test dataset were 4.6% and 0.58, 4.3% and 0.61, and 4.2% and 0.63 for the plan model, dosiomics model, and hybrid model, respectively. AUC and sensitivity at γ2%/2 mm in test dataset were 0.73 and 0.70, 0.81 and 0.90, and 0.83 and 0.90 for the plan model, dosiomics model, and hybrid model, respectively. CONCLUSIONS: A combination of both plan and dosiomics features with machine learning technique can improve the prediction and classification performance for GPR.

DOI： 10.1016/j.radonc.2020.07.031

PubMed

Publishing type：Research paper (scientific journal)   International / domestic magazine：International journal  

Plan evaluation is a key step in the radiotherapy treatment workflow. Central to this step is the assessment of treatment plan quality. Hence, it is important to agree on what we mean by plan quality and to be fully aware of which parameters it depends on. We understand plan quality in radiotherapy as the clinical suitability of the delivered dose distribution that can be realistically expected from a treatment plan. Plan quality is commonly assessed by evaluating the dose distribution calculated by the treatment planning system (TPS). Evaluating the 3D dose distribution is not easy, however; it is hard to fully evaluate its spatial characteristics and we still lack the knowledge for personalising the prediction of the clinical outcome based on individual patient characteristics. This advocates for standardisation and systematic collection of clinical data and outcomes after radiotherapy. Additionally, the calculated dose distribution is not exactly the dose delivered to the patient due to uncertainties in the dose calculation and the treatment delivery, including variations in the patient set-up and anatomy. Consequently, plan quality also depends on the robustness and complexity of the treatment plan. We believe that future work and consensus on the best metrics for quality indices are required. Better tools are needed in TPSs for the evaluation of dose distributions, for the robust evaluation and optimisation of treatment plans, and for controlling and reporting plan complexity. Implementation of such tools and a better understanding of these concepts will facilitate the handling of these characteristics in clinical practice and be helpful to increase the overall quality of treatment plans in radiotherapy.

DOI： 10.1016/j.radonc.2020.09.038

PubMed

Publishing type：Research paper (scientific journal)   International / domestic magazine：International journal  

Objective: To quantify and correct megavoltage (MV) scattered X-rays (MV-scatter) on an image acquired using a linac-mounted kilovoltage (kV) imaging subsystem. Methods and materials: A linac-mounted flat-panel detector (FPD) was used to acquire an image containing MV-scatter by activating the FPD only during MV beam irradiation. 6-, 10-, and 15 MV with a flattening-filter (FF; 6X-FF, 10X-FF, 15X-FF), and 6- and 10 MV without an FF (6X-FFF, 10X-FFF) were used. The maps were acquired by changing one of the irradiation parameters while the others remained fixed. The mean pixel values of the MV-scatter were normalized to the 6X-FF reference condition (MV-scatter value). An MV-scatter database was constructed using these values. An MV-scatter correction experiment with one full arc image acquisition and two square field sizes (FSs) was conducted. Measurement- and estimation-based corrections were performed using the database. The image contrast was calculated at each angle. Results: The MV-scatter increased with a larger FS and dose rate. The MV-scatter value factor varied substantially depending on the FPD position or collimator rotation. The median relative error ranges of the contrast for the image without, and with the measurement- and estimation-based correction were -10.9 to -2.9, and -1.5 to 4.8 and -7.4 to 2.6, respectively, for an FS of 10.0 × 10.0 cm2. Conclusions: The MV-scatter was strongly dependent on the FS, dose rate, and FPD position. The MV-scatter correction improved the image contrast. Advances in knowledge: The MV-scatters on the TrueBeam linac kV imaging subsystem were quantified with various MV beam parameters, and strongly depended on the fieldsize, dose rate, and flat panel detector position. The MV-scatter correction using the constructed database improved the image quality.

DOI： 10.1259/bjro.20190048

PubMed

Publishing type：Research paper (scientific journal)   International / domestic magazine：International journal  

PURPOSE: To validate the clinical applicability of knowledge-based (KB) planning in single-isocenter volumetric-modulated arc therapy (VMAT) for multiple brain metastases using the k-fold cross-validation (CV) method. METHODS: This study comprised 60 consecutive patients with multiple brain metastases treated with single-isocenter VMAT (28 Gy in five fractions). The patients were divided randomly into five groups (Groups 1-5). The data of Groups 1-4 were used as the training and validation dataset and those of Group 5 were used as the testing dataset. Four KB models were created from three of the training and validation datasets and then applied to the remaining Groups as the fourfold CV phase. As the testing phase, the final KB model was applied to Group 5 and the dose distributions were calculated with a single optimization process. The dose-volume indices (DVIs), modified Ian Paddick Conformity Index (mIPCI), modulation complexity scores for VMAT plans (MCSv), and the total number of monitor units (MUs) of the final KB plan were compared to those of the clinical plan (CL) using a paired Wilcoxon signed-rank test. RESULTS: In the fourfold CV phase, no significant differences were observed in the DVIs among the four KB plans (KBPs). In the testing phase, the final KB plan was statistically equivalent to the CL, except for planning target volumes (PTVs) D2% and D50% . The differences between the CL and KBP in terms of the PTV D99.5% , normal brain, and Dmax to all organs at risk (OARs) were not significant. The KBP achieved a lower total number of MUs and higher MCSv than the CL with no significant difference. CONCLUSIONS: We demonstrated that a KB model in a single-isocenter VMAT for multiple brain metastases was equivalent in dose distribution, MCSv, and total number of MUs to a CL with a single optimization.

DOI： 10.1002/acm2.13022

PubMed

Publishing type：Research paper (scientific journal)   International / domestic magazine：Domestic journal  

The number of patients with head and neck squamous cell carcinoma (HNC) with mediastinal involvement is small, and appropriate treatment techniques have not been widely discussed. This study aimed to compare the efficacy of radiotherapy planning techniques in reducing lung irradiation while retaining target coverage. Among all HNC patients with mediastinal involvement who underwent radiotherapy between 2007 and 2014 at our hospital, seven consecutive patients were included in this study. Four different treatment plans were generated for each patient as follows: seven-field intensity-modulated radiation therapy (IMRT), modified IMRT in which the lateral beams avoided the lungs, three-full-arc volumetric-modulated arc therapy (VMAT), and VMAT with lung avoidance. We compared the outcomes of IMRT and VMAT plans using the paired t-test. After modifications were made to avoid lung irradiation, IMRT values for V5Gy and V20Gy decreased from 713.2 to 503.6 cm3 (p = 0.011) and from 338.8 cm3 to 267.0 cm3 (p = 0.058), respectively. In the case of VMAT, lung V5Gy and V20Gy values decreased from 754.8 to 601.0 cm3 (p = 0.004) and from 328.5 to 255.7 cm3 (p = 0.020), respectively. Other factors did not significantly differ between the plans. In both IMRT and VMAT planning, lung doses were significantly reduced following the modification of the beams that cross the lungs with target coverage maintenance.

DOI： 10.1007/s12194-020-00559-2

PubMed

頭頸部扁平上皮細胞癌患者に対する放射線治療で、肺への照射線量を低減させるため、4種の異なる放射線治療計画を策定し、各種治療計画法を比較した。本治療計画では7照射野強度変調放射線療法(IMRT)、肺照射を回避した4水平ビームによるmodified IMRT、3フルアーク強度変調回転放射線療法(VMAT)、肺照射を回避したVMATの4種を適用し、縦隔病変を伴う頭頸部癌患者7例に施行した。その結果、肺照射を回避したmodified IMRTによるV5GyおよびV20GyのIMRT値は、713.2cm3から503.6cm3、338.8cm3から267.0cm3へ減少し、同様に肺照射を回避したVMATによるV5GyおよびV20GyのVMATでは、754.8cm3から601.0cm3、328.5cm3から255.7cm3への減少が認められた。以上の結果から、IMRTとVMATはともに治療計画により、肺を交差するビーム方向を修正することにより、肺への照射線量を有意に低減出来ることが確認された。

Publishing type：Research paper (scientific journal)   International / domestic magazine：International journal  

The aim of this study was to assess the impact of fractional dose and the number of arcs on interplay effects when volumetric modulated arc therapy (VMAT) is used to treat lung tumors with large respiratory motions. A three (fractional dose of 4, 7.5 or 12.5 Gy) by two (number of arcs, one or two) VMAT plan was created for 10 lung cancer cases. The median 3D tumor motion was 17.9 mm (range: 8.2-27.2 mm). Ten phase-specific subplans were generated by calculating the dose on each respiratory phase computed tomography (CT) scan using temporally assigned VMAT arcs. We performed temporal assignment of VMAT arcs using respiratory information obtained from infrared markers placed on the abdomens of the patients during CT simulations. Each phase-specific dose distribution was deformed onto exhale phase CT scans using contour-based deformable image registration, and a 4D plan was created by dose accumulation. The gross tumor volume dose of each 4D plan (4D GTV dose) was compared with the internal target volume dose of the original plan (3D ITV dose). The near-minimum 4D GTV dose (D99%) was higher than the near-minimum 3D internal target volume (ITV) dose, whereas the near-maximum 4D GTV dose (D1%) was lower than the near-maximum 3D ITV dose. However, the difference was negligible, and thus the 4D GTV dose corresponded well with the 3D ITV dose, regardless of the fractional dose and number of arcs. Therefore, interplay effects were negligible in VMAT-based stereotactic body radiation therapy for lung tumors with large respiratory motions.

DOI： 10.1093/jrr/rrz103

PubMed

呼吸性移動が大きく認められた肺癌患者を強度変調回転照射法(VMAT)で治療した場合、インタープレイ効果により、1回線量やアーク数がどのような影響を受けるか調査した。当院で蓄積した体幹部定位放射線治療に関するデータベースから、呼吸性移動が大きく認められた肺癌患者10例を選択し、1回線量は4Gy、7.5Gy、12.5Gyで、アーク数を1回もしくは2回に設定したVMAT治療計画を作成した。なお、患者に認められた3次元(D)での呼吸による腫瘍移動の中央値は17.9mm(8.2～27.2mm)であった。16列マルチスライスによる4次元画像撮像を行い、10種の呼吸位相CT画像を再構成し、CTシミュレーションでは、患者の腹部に設置した赤外線マーカから呼吸情報を取得後、VMATのアーク数を割り当てた。また、非剛体画像レジストレーションにより、呼気位相CT画像から変形画像を作成し、4D治療計画における肉眼的腫瘍体積線量(4D GTV線量)と3D治療計画における体内標的体積線量(3D ITV線量)を比較した。その結果、4D GTV線量での最小線量(D99%)は3D ITV線量に比べ高く、4D GTV線量での最大線量(D1%)では、3D ITV線量の最大線量に比べ低値が示された。しかし、これらの差異による影響は小さく、4D GTV線量は1回線量やアーク数に関係なく、3D ITV線量と良好に一致することが示された。以上より、大きな呼吸性移動を伴う肺腫瘍患者に認められる、VMATベース定位放射線療法で生じるインタープレイ効果は許容範囲内であるため、大きな影響は及ぼさないと考えられた。

Publishing type：Research paper (scientific journal)   International / domestic magazine：International journal  

PURPOSE: To assess the effects of different beam starting phases on dosimetric variations in the clinical target volume (CTV) and organs at risk (OARs), and to identify the relationship between plan complexity and the dosimetric impact of interplay effects in volumetric-modulated arc therapy (VMAT) plans for pancreatic cancer. METHODS: Single and double full-arc VMAT plans were generated for 11 patients. A dose of 50.4 Gy in 28 fractions was prescribed to cover 50% of the planning target volume. Patient-specific Digital Imaging and Communications in Medicine-Radiation Therapy plan files were divided into 10 files based on the respiratory phases in four-dimensional computed tomography (4DCT) simulations. The phase-divided VMAT plans were calculated in consideration of the beam starting phase for each arc and were then combined in the mid-ventilation phase of 4DCT (4D plans). The dose-volumetric parameters were compared with the calculated dose distributions without consideration of the interplay effects (3D plans). Additionally, relationships among plan parameters such as modulation complexity scores, monitor units (MUs), and dose-volumetric parameters were evaluated. RESULTS: Dosimetric differences in the median values associated with different beam starting phases were within ± 1.0% and ± 0.2% for the CTV and ± 0.5% and ± 0.9% for the OARs during single and double full-arc VMAT, respectively. Significant differences caused by variations in the beam starting phases were observed only for the dose-volumetric parameters of the CTV during single full-arc VMAT (P < 0.05), associated with moderate or strong correlations between the MUs and the dosimetric differences between the 4D and 3D plans. CONCLUSIONS: The beam starting phase affected CTV dosimetric variations of single full-arc VMAT. The use of double full-arc VMAT mitigated this problem. However, variation in the dose delivered to OARs was not dependent on the beam starting phase, even for single full-arc VMAT.

DOI： 10.1002/acm2.12720

PubMed

Publishing type：Research paper (scientific journal)   International / domestic magazine：International journal  

PURPOSE: The dosimetric accuracies of volumetric modulated arc therapy (VMAT) plans were predicted using plan complexity parameters via machine learning. METHODS: The dataset consisted of 600 cases of clinical VMAT plans from a single institution. The predictor variables (n = 28) for each plan included complexity parameters, machine type, and photon beam energy. Dosimetric measurements were performed using a helical diode array (ArcCHECK), and the dosimetric accuracy of the passing rates for a 5% dose difference (DD5%) and gamma index of 3%/3 mm (γ3%/3 mm) were predicted using three machine learning models: regression tree analysis (RTA), multiple regression analysis (MRA), and neural networks (NNs). First, the prediction models were applied to 500 cases of the VMAT plans. Then, the dosimetric accuracy was predicted using each model for the remaining 100 cases (evaluation dataset). The error between the predicted and measured passing rates was evaluated. RESULTS: For the 600 cases, the mean ± standard deviation of the measured passing rates was 92.3% ± 9.1% and 96.8% ± 3.1% for DD5% and γ3%/3 mm, respectively. For the evaluation dataset, the mean ± standard deviation of the prediction errors for DD5% and γ3%/3 mm was 0.5% ± 3.0% and 0.6% ± 2.4% for RTA, 0.0% ± 2.9% and 0.5% ± 2.4% for MRA, and -0.2% ± 2.7% and -0.2% ± 2.1% for NN, respectively. CONCLUSIONS: NNs performed slightly better than RTA and MRA in terms of prediction error. These findings may contribute to increasing the efficiency of patient-specific quality-assurance procedures.

DOI： 10.1002/mp.13669

PubMed

2007年12月～2017年5月までの期間内に、2.0cm3以上の計画標的腫瘍体積と判定された脳転移(2ヶ所)患者20例に対し、定位放射線治療において、multiple straight non-coplanar arcsを用いた single-isocenter volumetric-modulated arc therapy(VMAT)、およびsequential non-coplanar trajectoriesをベースとしたvolumetric-modulated Dynamic WaveArc therapy(VMDWAT)を行い、各々線量分布と治療時間を比較した。その結果、VMDWATでは、線量集中性の指標であるRadiology Therapy Oncology groupのconformity index(RTOG-CI)ならびにIan Paddickのconformity index(IP-CI)を用いて修正した指標mRTOG-CIとmIP-CIを大幅に改善させ、また、VMATと比べVMDWATでは、平均治療時間も短い傾向であることが示された。また、VMDWATとVMATが施行された患者においては、5Gy、10Gy、12Gy、15Gyおよび20Gy照射を受けた正常脳組織体積においても有意差がみられなかったことから、VMDWATはVMATに比べ、より短い治療時間で線量分布を大幅に改善させ、脳転移に極めて有用な治療法であることが示唆された。

Publishing type：Research paper (scientific journal)   International / domestic magazine：Domestic journal  

PURPOSE: A new irradiation technique, volumetric-modulated Dynamic WaveArc therapy (VMDWAT), based on sequential non-coplanar trajectories, can be performed using the Vero4DRT. This planning study compared the dose distribution and treatment time between single-isocenter volumetric-modulated arc therapy (VMAT) with multiple straight non-coplanar arcs and single-isocenter VMDWAT in patients with two brain metastases. MATERIALS AND METHODS: Twenty patients with two planning target volumes exceeding 2.0 cm3 were included. Both VMAT and VMDWAT plans were created with single isocenter and a prescribed dose of 28 Gy delivered in five fractions. Target conformity was evaluated using indices modified from the RTOG-CI (mRTOG-CI) and IP-CI (mIP-CI). RESULTS: VMDWAT significantly improved both mRTOG-CI and mIP-CI and reduced the volume of normal brain tissue receiving 25 and 28 Gy compared to VMAT. The two modalities did not significantly differ in terms of the volume of normal brain tissue receiving 5, 10, 12, 15, and 20 Gy. The mean treatment time was significantly shorter in the VMDWAT group. CONCLUSION: VMDWAT significantly improved dose distribution in a shorter treatment time compared to VMAT in patients treated for two brain metastases. Single-isocenter VMDWAT may thus be a promising treatment for two brain metastases.

DOI： 10.1007/s11604-019-00849-9

PubMed

J-GLOBAL

J-GLOBAL

J-GLOBAL

Publishing type：Research paper (scientific journal)   International / domestic magazine：International journal  

PURPOSE: To perform quality assurance of non-coplanar, volumetric-modulated arc therapy featuring continuous couch rotation (CCR-VMAT) using a C-arm linear accelerator. METHODS: We planned and delivered CCR-VMAT using the TrueBeam Developer Mode. Treatment plans were created for both a C-shaped phantom and five prostate cancer patients using seven CCR trajectories that lacked collisions; we used RayStation software (ver. 4.7) to this end. Subsequently, verification plans were generated. The mean absolute error (MAE) between the center of an MV-imaged steel ball and the radiation field was calculated using the Winston-Lutz test. The MAEs between planned and actual irradiation values were also calculated from trajectory logs. In addition, correlation coefficients (r values) among the MAEs of gantry angle, couch angle, and multi-leaf collimator (MLC) position, and mechanical parameters including gantry speed, couch speed, MLC speed, and beam output, were estimated. The dosimetric accuracies of planned and measured values were also assessed using ArcCHECK. RESULTS: The MAEs ±2 standard deviations as revealed by the Winston-Lutz test for all trajectories were 0.3 ± 0.3 mm in two dimensions. The MAEs of the gantry, couch, and MLC positions calculated from all trajectory logs were within 0.04°, 0.08°, and 0.02 mm, respectively. Deviations in the couch angle (r = 0.98, p < 0.05) and MLC position (r = 0.86, p < 0.05) increased significantly with speed. The MAE of the beam output error was less than 0.01 MU. The mean gamma passing rate ± 2 SD (range) of the 3%/3 mm, 3%/1 mm, and 5%/1 mm was 98.1 ± 1.9% (95.7-99.6%), 87.2 ± 2.8% (80.2-96.7%), and 96.3 ± 2.8% (93.9-99.6%), respectively. CONCLUSIONS: CCR-VMAT delivered via the TrueBeam Developer Mode was associated with high-level geometric and mechanical accuracy, thus affording to high dosimetric accuracy. The CCR-VMAT performance was stable regardless of the trajectory chosen.

DOI： 10.1186/s13014-019-1264-6

PubMed

Publishing type：Research paper (scientific journal)   International / domestic magazine：Domestic journal  

DOI： 10.11323/jjmp.39.4_91

PubMed

Publishing type：Research paper (scientific journal)  

DOI： 10.1016/S0167-8140(19)32249-2

Publishing type：Research paper (scientific journal)   International / domestic magazine：International journal  

Intensity-modulated radiotherapy (IMRT) is now regarded as an important treatment option for patients with locally advanced pancreatic cancer (LAPC). To reduce the underlying tumor motions and dosimetric errors during IMRT as well as the burden of respiratory management for patients, we started to apply a new treatment platform of the dynamic tumor dynamic tumor-tracking intensity-modulated radiotherapy (DTT-IMRT) using the gimbaled linac, which can swing IMRT toward the real-time tumor position under patients' voluntary breathing. Between June 2013 and March 2015, ten patients were treated, and the tumor-tracking accuracy and the practical benefits were evaluated. The mean PTV size in DTT-IMRT was 18% smaller than a conventional ITV-based PTV. The root-mean-squared errors between the predicted and the detected tumor positions were 1.3, 1.2, and 1.5 mm in left-right, anterior-posterior, and cranio-caudal directions, respectively. The mean in-room time was 24.5 min. This high-accuracy of tumor-tracking with reasonable treatment time are promising and beneficial to patients with LAPC.

DOI： 10.1038/s41598-018-35402-7

PubMed

Publishing type：Research paper (scientific journal)   International / domestic magazine：International journal  

Mono-isocentric volumetric-modulated arc therapy (VMAT) can be used to treat multiple brain metastases. It remains unknown whether mono-isocentric VMAT can improve the dose distribution compared with dual-isocentric dynamic conformal arc therapy (DCAT), especially for two brain metastases. We compared the dose distribution between dual-isocentric DCAT and mono-isocentric VMAT for two large brain metastases, and analyzed the relationship between the distance between the two targets and the difference in dose distribution. A total of 19 patients, each with two large brain metastases, were enrolled. The dose prescribed for each planning target volume (PTV) was 28 Gy in five fractions (D99.8 = 100%). We created new indices derived from conformity indices suggested by the Radiation Therapy Oncology Group (RTOG; mRTOG-CI) and Paddick et al. (mIP-CI), using the dosimetric parameters of the sum of the two PTVs. The median PTV was 5.05 cm3 (range, 2.10-28.47). VMAT significantly improved mRTOG-CI and mIP-CI compared with DCAT. In all cases, VMAT was able to improve mRTOG-CI and mIP-CI compared with DCAT. Whereas the normal brain volume receiving 5 Gy was similar between the two modalities, the normal brain receiving 10, 12, 15, 20, 25 and 28 Gy (V10-V28) was significantly smaller in VMAT. The mean beam-on times were 213.3 s and 121.9 s in DCAT and VMAT, respectively (P < 0.001). Mono-isocentric VMAT improved the target conformity and reduced the beam-on time and V10-V28 of the normal brain for not only two close metastases but also two distant metastases. Mono-isocentric VMAT seems to be a promising treatment technique for two large brain metastases.

DOI： 10.1093/jrr/rry064

PubMed

2008年1月～2016年7月までの期間内に、著者等の施設で治療を受けた脳転移患者のうち、腫瘍が2ヶ所あり、計画標的体積(PTV)が2cm3以上で、小分割定位放射線療法が施行された患者19例を対象とし、脳転移に対するDCATとVMATの線量分布を比較した。なお、各PTVの処方線量は5分画中28Gyで、線量集中性の指標としては、RTOGおよびPaddickらが規定したconformity indexを用いて、腫瘍2ヶ所のPTVの総線量測定パラメータから、それぞれ指数を算定し評価した。その結果、PTV中央値は5.05(範囲2.10～28.47cm3)で、mono-isocentric VMATはDCATに比し、腫瘍近傍の転移や遠隔転移を含む全例において、両指数とも有意な改善が認められた。また、平均ビームオンタイムはVMATで213.3秒、DCATで121.9秒で、5Gy照射の正常脳への照射体積はVMATとDCATともに同等の数値が示されたが、10～28Gy照射ではVMATで有意に小さいことが明らかにされた。以上の結果から、mono-isocentric VMATが、大きな脳転移病巣を2ヶ所有する患者に対し、有用性が高いことが示唆された。

Publishing type：Research paper (scientific journal)   International / domestic magazine：International journal  

PURPOSE: The aim was to examine the feasibility of a dynamic tumor-tracking volumetric modulated arc therapy (DTT-VMAT) technique using a gimbal-mounted linac and assess its positional, mechanical and dosimetric accuracy. MATERIALS AND METHODS: DTT-VMAT was performed using a surrogated signal-based technique. The positional tracking accuracy was evaluated as the difference between the predicted and detected target positions for various wave patterns. Mechanical accuracy measurements included gantry, multileaf collimator (MLC) and gimbal positions. The differences between the command and the measured positions were evaluated for various wave patterns. Dosimetric verification was performed using Gafchromic EBT3 films in the benchmark phantom and two clinical cases. RESULTS: The root mean square error (RMSE) of the positional accuracy was within 0.31 mm. The RMSE of mechanical accuracy was within 0.14° for the gantry, 0.11 ± 0.02 mm for the MLC and 0.13 mm for the gimbal positions. The passing rate of the 3%/3 mm gamma index was greater than 83.3% and 91.2% for the benchmark phantom and two clinical cases, respectively. CONCLUSIONS: The positional, mechanical and dosimetric accuracy of DTT-VMAT were evaluated. DTT-VMAT with a gimbal-mounted linac had sufficient accuracy and presents a new strategy for treatment of several tumors with respiratory motion.

DOI： 10.1016/j.radonc.2017.10.034

PubMed

J-GLOBAL

Publishing type：Research paper (scientific journal)   International / domestic magazine：Domestic journal  

BACKGROUND: The aim of this study was to assess the clinical outcomes of acoustic neuromas (ANs) treated with hypofractionated stereotactic radiotherapy (hypo-FSRT) prescribed at a uniform dose. METHODS: Forty-seven patients with a unilateral AN were treated consecutively with hypo-FSRT between February 2007 and March 2012. Nineteen patients maintained a serviceable hearing status at the beginning of hypo-FSRT. The prescribed dose was 25 Gy delivered in five fractions per week to the isocenter, and the planning target volume was covered by the 80% isodose line. RESULTS: The median follow-up and audiometric follow-up periods were 61 and 52 months, respectively. The estimated tumor control rate at 5 years was 90% (95% CI 76-96). The existence of the cystic component before hypo-FSRT had a significantly worse impact on tumor control (p = 0.02). The estimated hearing preservation rates at 1, 3 and 5 years were 68% (95% CI 42-84), 41% (95% CI 20-62) and 36% (95% CI 15-57), respectively. A borderline significant difference was identified in the mean biological effective dose with an α/β value of 3 Gy (BED3) to the ipsilateral cochlea between the preserved hearing and hearing loss groups (19 Gy vs. 28 Gy) (p = 0.08). CONCLUSIONS: Hypo-FSRT delivered in five fractions for unilateral ANs may achieve excellent tumor control with no severe facial or trigeminal complications. The mean BED3 in the cochlea may impact the hearing preservation rate. Therefore, the cochlear dose should be as low as possible.

DOI： 10.1007/s10147-018-1267-6

PubMed

均一線量で処方された寡分割定位照射療法にて聴神経腫瘍を治療した時の臨床成績を後ろ向きに解析した。片側性聴神経腫瘍に罹患し、2007年2月～2012年3月に寡分割定位照射療法にて加療された患者47例(女性26例、年齢25～82歳)を解析対象とした。処方線量は25Gyで週5回に分割して照射した。当照射療法の開始時点で実用聴力を有していた患者は19例で、追跡期間の中央値は61ヵ月、聴力検査が行えていた追跡期間の中央値は52ヵ月であった。5年腫瘍制御率の推定値は90%であった。照射療法前に嚢胞成分が存在することは、腫瘍制御を悪化させる影響を与える因子であることが有意に示された。1年、3年、5年聴力温存率の推定値はそれぞれ68%、41%、36%であった。α/β値を3Gyとした時の片側蝸牛に対する平均生物学的等価線量(BED3)は聴力温存群では19Gy、聴力喪失群では28Gyとなり、両群間で境界領域の有意性(p=0.08)が示された。片側性聴神経腫瘍に対し5分割の寡分割定位照射療法を施行することで顔面神経・三叉神経の重度合併症を引き起こすことなく優れた腫瘍制御を達成できると考えられた。

Publishing type：Research paper (scientific journal)   International / domestic magazine：International journal  

Objectives: We performed dynamic tumor-tracking IMRT (DTT-IMRT) in locally advanced pancreatic cancer (LAPC) patients using a gimbaled linac of Vero4DRT. The purpose of this study is to report the first clinical results. Methods: From June 2013 to June 2015, eleven LAPC patients enrolled in this study and DTT-IMRT was successfully performed. The locoregional progression free survival (LRPFS), distant metastasis free survival (DMFS), overall survival (OS), hematologic and gastrointestinal (GI) toxicities were evaluated. Oncologic outcomes were estimated using Kaplan-Meier analysis, and toxicities using CTCAE v4.0. Results: The median radiation dose was 48 Gy (range, 45-51) in 15 fractions. Concurrent chemoradiotherapy (CCRT) was performed using gemcitabine in 9 patients and S-1 in one, while one patient refused. With a median follow-up of 22.9 months, 1-year LRPFS, DMFS, and OS rates were 90.9%, 70.7%, and 100%, respectively. Median survival time was 23.6 months. Grade-3 leucopenia and neutropenia were observed in two (18%) and one patient (9%), respectively. Grade-2 acute GI toxicity occurred in 2 patients (18%) and late grade-3 in 1 patient (9%). Conclusions: Preliminarily application of DTT-IMRT using a gimbaled linac on CCRT in LAPC patients resulted in excellent locoregional control and OS without severe toxicity.

DOI： 10.18632/oncotarget.25310

PubMed

Publishing type：Research paper (scientific journal)   International / domestic magazine：International journal  

The purpose of this study was to develop a simple verification method for the routine quality assurance (QA) of Dynamic WaveArc (DWA) irradiation using electronic portal imaging device (EPID) images and log data analysis. First, an automatic calibration method utilizing the outermost multileaf collimator (MLC) slits was developed to correct the misalignment between the center of the EPID and the beam axis. Moreover, to verify the detection accuracy of the MLC position according to the EPID images, various positions of the MLC with intentional errors in the range 0.1-1 mm were assessed. Second, to validate the geometric accuracy during DWA irradiation, tests were designed in consideration of three indices. Test 1 evaluated the accuracy of the MLC position. Test 2 assessed dose output consistency with variable dose rate (160-400 MU/min), gantry speed (2.2-6°/s), and ring speed (0.5-2.7°/s). Test 3 validated dose output consistency with variable values of the above parameters plus MLC speed (1.6-4.2 cm/s). All tests were delivered to the EPID and compared with those obtained using a stationary radiation beam with a 0° gantry angle. Irradiation log data were recorded simultaneously. The 0.1-mm intentional error on the MLC position could be detected by the EPID, which is smaller than the EPID pixel size. In Test 1, the MLC slit widths agreed within 0.20 mm of their exposed values. The averaged root-mean-square error (RMSE) of the dose outputs was less than 0.8% in Test 2 and Test 3. Using log data analysis in Test 3, the RMSE between the planned and recorded data was 0.1 mm, 0.12°, and 0.07° for the MLC position, gantry angle, and ring angle, respectively. The proposed method is useful for routine QA of the accuracy of DWA.

DOI： 10.1002/acm2.12324

PubMed

Publishing type：Research paper (scientific journal)   International / domestic magazine：International journal  

PURPOSE: To identify dosimetric advantages of the novel Dynamic WaveArc (DWA) technique for accelerated partial breast irradiation (APBI), compared with non-coplanar three-dimensional conformal radiotherapy (nc3D-CRT) and coplanar tangential volumetric modulated arc therapy (tVMAT) with dual arcs of 45-65°. METHODS: Vero4DRT enables DWA by continuous gantry rotation and O-ring skewing with movement of the multi-leaf collimator. We compared the dose distributions of DWA, nc3D-CRT and tVMAT in 24 consecutive left-sided breast cancer patients treated with APBI (38.5 Gy in 10 fractions). The average doses and volumes to the planning target volume (PTV) and organs at risk, especially heart and left anterior descending artery (LAD) were compared among DWA, nc3D-CRT and tVMAT. RESULTS: The doses and volumes to the PTVs did not differ significantly among the three plans. For the DWA plans, the mean dose to the heart was 0.2 ± 0.1 Gy, less than those of the nc3D-CRT and tVMAT plans. The D2% values of the planning organ at risk volume of the LAD were 9.3 ± 10.9%, 28.2 ± 31.9% and 20.3 ± 25.7% for DWA, nc3D-CRT and tVMAT, respectively. The V20Gy and V10Gy of the ipsilateral lung for the DWA plans were also significantly lower. CONCLUSIONS: DWA allowed to find a better compromise for OAR which overlapped with the PTV. Use of the DWA for APBI improved the dose distributions compared with those of nc3D-CRT and tVMAT.

DOI： 10.1016/j.ejmp.2018.03.015

PubMed

Publishing type：Research paper (scientific journal)   International / domestic magazine：International journal  

PURPOSE: Our aim was to develop a portable quality control (QC) application using a thermometer, a barometer, an angle gauge, and a range finder implemented in a tablet-type consumer electronic device (CED) and to assess the accuracies of the measurements made. METHODS: The QC application was programmed using Java and OpenCV libraries. First, temperature and atmospheric pressure were measured over 30 days using the temperature and pressure sensors of the CED and compared with those measured by a double-tube thermometer and a digital barometer. Second, the angle gauge was developed using the accelerometer of the CED. The roll and pitch angles of the CED were measured from 0 to 90° at intervals of 10° in the clockwise (CW) and counterclockwise (CCW) directions. The values were compared with those measured by a digital angle gauge. Third, a range finder was developed using the tablet's built-in camera and image-processing capacities. Surrogate markers were detected by the camera and their positions converted to actual positions using a homographic transformation method. Fiducial markers were placed on a treatment couch and moved 100 mm in 10-mm steps in both the lateral and longitudinal directions. The values were compared with those measured by the digital output of the treatment couch. The differences between CED values and those of other devices were compared by calculating means ± standard deviations (SDs). RESULTS: The means ± SDs of differences in temperature and atmospheric pressure were -0.07 ± 0.25°C and 0.05 ± 0.10 hPa, respectively. The means ± SDs of the difference in angle was -0.17 ± 0.87° (0.15 ± 0.23° degrees excluding the 90° angle). The means ± SDs of distances were 0.01 ± 0.07 mm in both the lateral and longitudinal directions. CONCLUSIONS: Our portable QC application was accurate and may be used instead of standard measuring devices. Our portable CED is efficient and simple when used in the field of medical physics.

DOI： 10.1002/mp.12786

PubMed

DOI： 10.1016/j.meddos.2017.10.009

PubMed

Publishing type：Research paper (scientific journal)   International / domestic magazine：International journal  

DOI： 10.1016/j.ejmp.2017.07.020

PubMed

Publishing type：Research paper (scientific journal)  

DOI： 10.1016/j.prro.2017.04.004

PubMed

Publishing type：Research paper (scientific journal)   International / domestic magazine：International journal  

DOI： 10.1016/j.ejmp.2017.10.023

PubMed

Publishing type：Research paper (scientific journal)   International / domestic magazine：International journal  

PURPOSE: To quantify the 3-dimensional pancreatic tumor motion during the overall treatment course using real-time orthogonal kilovoltage X-ray imaging. METHODS AND MATERIALS: This study included 10 patients with pancreatic cancer who underwent 6-port static intensity modulated radiation therapy with real-time tumor tracking in 15 fractions, except for 1 patient (5 fractions). The tumor and abdominal wall positions were acquired simultaneously during the overall treatment course. Then the tumor motion amplitude and reference positions were determined. RESULTS: The mean tumor amplitudes were 4.9, 6.5, and 13.4 mm in the left-right (LR), anterior-posterior (AP), and superior-inferior (SI) directions, respectively. The intrafractional variations of the reference tumor position were up to 5.4, 10.2, and 10.7 mm in the LR, AP, and SI directions, and those of the reference abdominal position were up to 10.5 mm. The reference tumor position drifted significantly in the AP and SI directions after 10 minutes, and that of abdominal wall motion drifted during the first 15 minutes (P<.05). The interfractional variation of the reference tumor position after setup correction, based on bony structures, was up to 8.9, 9.8, and 11.0 mm in the LR, AP, and SI directions, respectively. CONCLUSIONS: Appropriate respiratory motion management techniques should be applied for the accurate localization of pancreatic tumors.

DOI： 10.1016/j.ijrobp.2017.03.042

PubMed

Publishing type：Research paper (scientific journal)   International / domestic magazine：International journal  

DOI： 10.1002/mp.12351

PubMed

Publishing type：Research paper (scientific journal)   International / domestic magazine：International journal  

DOI： 10.1016/j.radonc.2017.04.023

PubMed

Publishing type：Research paper (scientific journal)  

DOI： 10.1016/s0167-8140(17)31988-6

Publishing type：Research paper (scientific journal)  

DOI： 10.1016/s0167-8140(17)31274-4

Publishing type：Research paper (scientific journal)   International / domestic magazine：International journal  

DOI： 10.1016/j.ejmp.2017.02.004

PubMed

Publishing type：Research paper (scientific journal)   International / domestic magazine：International journal  

DOI： 10.1118/1.4966130

PubMed

Publishing type：Research paper (scientific journal)  

DOI： 10.1088/2057-1976/2/6/065007

Publishing type：Research paper (scientific journal)  

DOI： 10.1016/j.ejmp.2015.06.012

PubMed

Publishing type：Research paper (scientific journal)   International / domestic magazine：International journal  

DOI： 10.1016/j.ejmp.2015.06.012

PubMed

Publishing type：Research paper (scientific journal)   International / domestic magazine：International journal  

DOI： 10.1120/jacmp.v16i5.5679

PubMed

Publishing type：Research paper (scientific journal)   International / domestic magazine：International journal  

DOI： 10.1120/jacmp.v16i4.5222

PubMed

DOI： 10.1120/jacmp.v16i4.5222

PubMed

Publishing type：Research paper (scientific journal)   International / domestic magazine：International journal  

DOI： 10.1016/j.radonc.2015.05.003

PubMed

Publishing type：Research paper (scientific journal)   International / domestic magazine：International journal  

DOI： 10.1016/j.ejmp.2015.01.004

PubMed

Publishing type：Research paper (scientific journal)   International / domestic magazine：International journal  

DOI： 10.1120/jacmp.v16i2.4896

PubMed

強度変調放射線治療における線量検証の標準化について検討した。IMRTを実施している129施設を対象とした。前立腺は96.6%、頭頸部は64.3%、脳腫瘍は53.5%の施設でIMRTが実施されていた。IMRT QAの実務担当者を3人以上確保できている施設は全体の77.5%であった。前立腺IMRTにおけるQA項目では、吸収線量検証は94.4%、線量分布検証は96.8%の施設が実施していたが、フルエンス検証の実施率は24.8%であった。約85%以上の施設でSuperposition法相当以上の線量計算精度の高いアルゴリズムが使用されていた。ファントムに対する補正係数を使用している施設は51.1%であった。逸脱時の対処方法としては、QAプランの再確認、逸脱前と同じ位置での再測定が多く、次いで逸脱前と別の位置での再測定、線量算出に使用している係数や線量・濃度曲線等の再確認を実施する施設が多かった。

Publishing type：Research paper (scientific journal)  

DOI： 10.1120/jacmp.v16i5.5679

PubMed

Publishing type：Research paper (scientific journal)   International / domestic magazine：International journal  

DOI： 10.1016/j.radonc.2014.08.003

PubMed

原発性肺癌を定位放射線療法で治療した患者の転帰に及ぼす腹部圧迫の影響について検討した。2004年1月から2009年3月に、京都大学医学部附属病院で定位放射線療法により治療を行った非小細胞肺癌患者47人のデータをレトロスペクティブに調べ、腹部圧迫を行ったグループ22人および行わないグループ25人の全生存率、局所制御率および無病生存率を比較した。経過観察期間の中央値は42.6ヵ月であった。二つのグループの3年の全生存率、局所制御率および無病生存率に統計的に有意差はなかったが、局所制御率に最も大きな差が認められ、腹部圧迫なしの患者の82.5%に対して、腹部圧迫を行った患者では65.4%であった。患者を性別およびTステージにより予後グループに階層化すると、予後不良グループにおいて局所制御の違いが増大することが分かった。以上より、腹部圧迫は定位放射線療法後の低い局所制御率と関連する可能性が示唆された。

Publishing type：Research paper (scientific journal)   International / domestic magazine：International journal  

DOI： 10.1093/jrr/rru028

PubMed

Publishing type：Research paper (scientific journal)  

Purpose:

To compare isocenter (IC) dose between X‐ray Voxel Monte Carlo (XVMC) and Acuros XB (AXB) as part of an independent verification of monitor unit (MU) calculation for lung stereotactic body radiation therapy (SBRT) using a secondary independent treatment planning system (TPS).

Methods:

Treatment plans of 110 lesions from 101 patients who underwent lung SBRT with Vero4DRT (Mitsubishi Heavy Industries, Ltd., Japan, and BrainLAB, Feldkirchen, Germany) were evaluated retrospectively. Dose distribution was calculated with X‐ray Voxel Monte Carlo (XVMC) in iPlan 4.5.1 (BrainLAB, Feldkirchen, Germany) on averaged intensity projection images. A spatial resolution and mean variance were 2 mm and 2%, respectively. The clinical treatment plans were transferred from iPlan to Eclipse (Varian Medical Systems, Palo Alto, CA, USA), and doses were recalculated with well commissioned AXB ver. 11.0.31 while maintaining the XVMC‐calculated MUs and beam arrangement. Dose calculations were made in the dose‐to‐medium dose reporting mode with the calculation grid size of 2.5 mm. The mean and standard deviation (SD) of the IC dose difference between XVMC and AXB were calculated. The tolerance level was defined as |mean|+2SD. Additionally, the relationship between IC dose difference and the size of planning target volume (PTV) or computed tomography (CT) value of internal target volume (ITV) was evaluated.

Results:

The mean±SD of the IC dose difference between XVMC and AXB was −0.32±0.73%. The tolerance level was 1.8%. Absolute IC dose differences exceeding the tolerance level were observed in 3 patients (2.8%). There were no strong correlations between IC dose difference and PTV size (R=−0.14) or CT value of ITV (R=−0.33).

Conclusion:

The present study suggested that independent verification of MU calculation for lung SBRT using a secondary TPS is useful.

DOI： 10.1118/1.4888684

Publishing type：Research paper (scientific journal)   International / domestic magazine：International journal  

DOI： 10.1016/j.radonc.2014.02.018

PubMed

Publishing type：Research paper (scientific journal)   International / domestic magazine：International journal  

DOI： 10.1016/j.radonc.2014.01.014

PubMed

International / domestic magazine：Domestic journal  

PURPOSE: The purpose of this study was to investigate the status of the implementation of quality assurance (QA) for intensity-modulated radiation therapy (IMRT) in Japan using a questionnaire survey. METHODS: The questionnaire consisted of seven sections: (1) clinical uses of IMRT, (2) treatment planning systems, treatment machines, phantoms for verification and CT scanning, (3) absorbed dose verification, (4) dose distribution verification, (5) fluence map verification, (6) acceptance criteria for each verification, and (7) comments. RESULTS: The questionnaire was completed by 129 institutions (response rate: 76.8%). IMRT was performed for prostate cancer in 125 institutions (96.9%), followed by head and neck cancer in 83 (64.3%), and brain tumors in 69 (53.5%). Although at least three individuals were engaged in IMRT QA in 77.5% of the institutions, the number of full-time persons involved in IMRT QA was one or less in 94 institutions (72.9%). This indicated that most institutions in Japan have a staff shortage. More than 90% of the institutions verified both the absorbed dose and dose distribution. The acceptance criterion for the absorbed dose verification was set to ±3% in at least 80% of the institutions. Gafchromic film was used for the majority of dose distribution verifications. The acceptance criteria for dose distribution verification mainly involved gamma analysis and a comparison of dose profiles; however, the judgment of acceptance did not depend on the results of the gamma analysis. CONCLUSION: This survey increases our understanding of how institutions currently perform IMRT QA analysis. This understanding will help to move institutions toward more standardization of IMRT QA in Japan.

PubMed

J-GLOBAL

Publishing type：Research paper (scientific journal)   International / domestic magazine：International journal  

DOI： 10.1120/jacmp.v14i5.4488

PubMed

Publishing type：Research paper (scientific journal)   International / domestic magazine：International journal  

DOI： 10.1118/1.4817236

PubMed

Publishing type：Research paper (scientific journal)   International / domestic magazine：International journal  

DOI： 10.1118/1.4794506

PubMed

Publishing type：Research paper (scientific journal)   International / domestic magazine：Domestic journal  

DOI： 10.1007/s12194-012-0182-1

PubMed

新生児の胸部X線検査における被験者とオペレーターの被曝線量低減における新しいフラットパネル検出器(FPD)CXDI-60Cを装着したデジタルモバイルX線システムの有用性について検討した。本システムについて、種々の管電圧に対するデジタル特性を調べ、集中治療室内のインキュベーターに置いた水等価ファントムに対する入射表面線量(ESD)を皮膚被曝線量計で測定した。また、インキュベーター周囲の散乱放射線を電離箱式照射線量率計で測定した。本システムは優れた直線性を示すデジタル特性と、管電圧に対して安定なコントラスト特性を示した。本システムにおける1回照射でのESDは、8cmの厚さのファントムで51～52μGy、4.5cmの厚さのファントムで33～34μGyで、インキュベーター周囲の線量は0.1～0.6μSvから測定限界以下であった。以上より、本システムは胸部X線撮影において被験者やオペレーターに対するESDを低減できる可能性が示唆された。

Publishing type：Research paper (scientific journal)   International / domestic magazine：International journal  

DOI： 10.1016/j.meddos.2012.07.007

PubMed

Publishing type：Research paper (international conference proceedings)  

DOI： 10.1118/1.4814605

Publishing type：Research paper (international conference proceedings)  

DOI： 10.1118/1.4814235

Publishing type：Research paper (scientific journal)   International / domestic magazine：International journal  

DOI： 10.1118/1.4754648

PubMed

Publishing type：Research paper (scientific journal)   International / domestic magazine：International journal  

DOI： 10.1118/1.4754592

PubMed

DOI： 10.1118/1.4735426

DOI： 10.1118/1.4736210

DOI： 10.1118/1.4734627

Publishing type：Research paper (scientific journal)   International / domestic magazine：International journal  

DOI： 10.1016/j.ijrobp.2010.08.014

PubMed

Publishing type：Research paper (international conference proceedings)  

DOI： 10.1118/1.3612635

Publishing type：Research paper (scientific journal)   International / domestic magazine：International journal  

DOI： 10.1093/jjco/hyp115

PubMed

日本人限局前立腺癌例に対する治療設計の過程を確認するため、無作為で全国61施設の医療実態調査研究を実施し、2003～05年に遠隔転移のない前立腺癌に対し根治的外部照射療法を施行された計397例について、放射線治療の計画および照射の評価を行った。患者の90%はCTデータを基に治療計画が立てられ、シミュレーションおよび治療はほぼ全例が背臥位で施行された。固定装置使用は15%の患者のみで、殆どは照射野の照合にはポータルフィルムまたは電子ポータル画像装置が用いられ、初期治療やポータル量変化に加えて定期的または多重照合が行われたのは30%に過ぎなかった。本調査結果から、本邦の限局前立腺癌に対する放射線治療設計および照射方法の現状における一定の傾向が明らかになった。

Publishing type：Research paper (scientific journal)   International / domestic magazine：International journal  

PubMed

Publishing type：Research paper (scientific journal)   International / domestic magazine：International journal  

DOI： 10.1016/j.ijrobp.2009.02.088

PubMed

Publishing type：Research paper (scientific journal)   International / domestic magazine：International journal  

DOI： 10.1016/j.ijrobp.2008.08.067

PubMed

Publishing type：Research paper (scientific journal)  

DOI： 10.1016/j.ijrobp.2008.06.372

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DOI： 10.1118/1.4956369

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DOI： 10.11323/jjmp.34.4_208

Other URL： https://search.jamas.or.jp/default/link?pub_year=2015&ichushi_jid=J03418&link_issn=&doc_id=20150421570001&doc_link_id=1390001205509475968&url=https%3A%2F%2Fcir.nii.ac.jp%2Fcrid%2F1390001205509475968&type=CiNii&icon=https%3A%2F%2Fjk04.jamas.or.jp%2Ficon%2F00003_3.gif

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DOI： 10.1007/978-3-642-29305-4_471

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DOI： 10.1118/1.3611919

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