Search

This study aimed to clarify the motivations and timing of the decision to become radiation oncologists., Materials and Methods: We conducted an online survey for new members of the Japanese Society for Radiation Oncology (JASTRO)., Results: The response rate was 43.3%. Data of the 79 respondents who wanted to obtain a board-certification of JASTRO were analysed. We divided the respondents into two groups: Group A, those who entered a single radiation oncology department, and Group B, those who joined a radiology department in which the radiation oncology department and diagnostic radiology department were integrated. The most common period when respondents were most attracted to radiation oncology was "5th year of university" in Group A and "2nd year of junior residency" and "senior residency" in Group B. Furthermore, 79.5% of Group A and 40% of Group B chose periods before graduation from a university with a significant difference. The most common period when respondents made up their minds to become radiation oncologists was "2nd year of junior residency" in both groups. Internal medicine was the most common department to consider if they did not join the radiation oncology or radiology department., Conclusion: To increase the radiation oncologists, it is crucial to enhance clinical training in the fifth year of university for Group A and to continue an active approach to maintain interest in radiation oncology until the end of junior residency. In Group B facilities, it is desirable to provide undergraduates more opportunities to come in contact with radiation oncology., (© The Author(s) 2020. Published by Oxford University Press on behalf of The Japanese Radiation Research Society and Japanese Society for Radiation Oncology.)

Background: Although definitive external-beam radiotherapy (EBRT) is one of the treatment options for non-metastatic castration-resistant prostate cancer (NM-CRPC), there are limited data on the long-term outcomes of this treatment., Methods: We retrospectively evaluated 31 NM-CRPC patients consecutively treated with definitive EBRT. The median age was 74 years upon EBRT initiation. The initial T stage distribution was as follows: T1c in 3, T2 in 11, T3 in 14, and T4 in 3 cases, respectively. The median prostate dose was 70.4 Gy. A castration-resistant status was defined as continuously increasing serum prostate-specific antigen levels despite ongoing hormonal therapy (HT)., Results: The median follow-up duration after EBRT was 66.6 months. The median period of primary HT was 18.0 months. The 5- and 8-year overall survival rates were 74.6 and 49.8%, respectively. The 5- and 8-year prostate cancer-specific survival rates were 77.4 and 51.7%, respectively. Fourteen patients died, and prostate cancer was the cause of death in 12 of these patients. The 5- and 8-year relapse-free survival rates were 32.3 and 25.8%, respectively. Among 23 patients who experienced biochemical or clinical failure, the median duration to recurrence after EBRT was 19.3 months. The 5- and 8-year clinical failure-free survival rates were 56.0 and 51.4%, respectively. Among the 14 patients who experienced clinical failure, the median duration after EBRT was 16.0 months. The local relapse-free rates at 5 and 8 years were 91.0 and 91.0%, respectively. Grade 3 or higher adverse events were observed in four patients., Conclusion: Definitive EBRT achieved a long-term disease-free and clinical failure-free status in approximately one-third of and half of the treated NM-CRPC patients, respectively. This approach was also associated with favorable local relapse-free rates and overall survival outcomes. Definitive EBRT is a promising approach for NM-CRPC patients.

Purpose: To explore the effect of sampling interval of training data acquisition on the intrafractional prediction error of surrogate signal-based dynamic tumor-tracking using a gimbal-mounted linac., Materials and Methods: Twenty pairs of respiratory motions were acquired from 20 patients (ten lung, five liver, and five pancreatic cancer patients) who underwent dynamic tumor-tracking with the Vero4DRT. First, respiratory motions were acquired as training data for an initial construction of the prediction model before the irradiation. Next, additional respiratory motions were acquired for an update of the prediction model due to the change of the respiratory pattern during the irradiation. The time elapsed prior to the second acquisition of the respiratory motion was 12.6 ± 3.1 min. A four-axis moving phantom reproduced patients' three dimensional (3D) target motions and one dimensional surrogate motions. To predict the future internal target motion from the external surrogate motion, prediction models were constructed by minimizing residual prediction errors for training data acquired at 80 and 320 ms sampling intervals for 20 s, and at 500, 1,000, and 2,000 ms sampling intervals for 60 s using orthogonal kV x-ray imaging systems. The accuracies of prediction models trained with various sampling intervals were estimated based on training data with each sampling interval during the training process. The intrafractional prediction errors for various prediction models were then calculated on intrafractional monitoring images taken for 30 s at the constant sampling interval of a 500 ms fairly to evaluate the prediction accuracy for the same motion pattern. In addition, the first respiratory motion was used for the training and the second respiratory motion was used for the evaluation of the intrafractional prediction errors for the changed respiratory motion to evaluate the robustness of the prediction models., Results: The training error of the prediction model was 1.7 ± 0.7 mm in 3D for all sampling intervals. The intrafractional prediction error for the same motion pattern was 1.9 ± 0.7 mm in 3D for an 80 ms sampling interval, which increased larger than 1 mm in 10.0% of prediction models trained at a 2,000 ms sampling interval with a significant difference (P < 0.01) and up to 2.5% for the other sampling intervals without a significant difference (P > 0.05). The intrafractional prediction error for the changed respiratory motion pattern increased to 5.1 ± 2.4 mm in 3D for an 80 ms sampling interval; however, there was not a significant difference in the robustness of the prediction model between the 80 ms sampling interval and other sampling intervals (P > 0.05)., Conclusions: Although the training error of the prediction model was consistent for the all sampling intervals, the prediction model using the larger sampling interval of the 2,000 ms increased the intrafractional prediction error for the same motion pattern. The realistic accuracy of the prediction model was difficult to estimate using the larger sampling interval during the training process. It is recommended to construct the prediction model at sampling interval ≤ 1,000 ms and to reconstruct the model during treatment., (© 2017 The Authors. Medical Physics published by Wiley periodicals, Inc. on behalf of American Association of Physicists in Medicine.)

Background: Although hypofractionated radiotherapy (HFRT) is preferred to conventionally fractionated radiotherapy when treating elderly patients with glioblastoma, the benefits and tolerability of HFRT with concurrent temozolomide (TMZ) remain unknown for such patients. We assessed the feasibility and outcomes of elderly patients with glioblastoma treated with HFRT and concurrent TMZ., Methods: We retrospectively reviewed the medical records of 11 patients aged ≥70 years who were treated with HFRT and concurrent TMZ. All patients had newly diagnosed and histologically confirmed glioblastoma and were treated at our institution between October 2011 and April 2015. The median age was 74 years (range, 70-85 years). Total resection/subtotal resection/biopsy were performed in 2/5/4 patients, respectively. The planning target volume included the T1-enhancing tumor and the resection cavity plus 2-cm margins, and all surrounding edema. The median prescription dose was 35 Gy (range, 35-42.5 Gy), delivered in 10 fractions. Seven patients received TMZ at 150 mg/m 2 for 5 days and 4 received TMZ at 75 mg/m 2 during HFRT. Overall survival (OS) was defined as the time from surgery to death or the last follow-up., Results: The median follow-up period was 13.2 months. The median OS and progression-free survival (PFS) times were 13.2 and 7.0 months, respectively. One patient experienced grade 4 neutropenia, lymphocytopenia, and thrombocytopenia. No grade 3 or higher nonhematological adverse event was noted., Conclusion: Our analysis demonstrated the feasibility of HFRT with concurrent TMZ used to treat elderly patients with glioblastoma. Further prospective clinical trials are needed to define therapies that balance efficacy with tolerability.

Purpose: To assess the target localization error (TLE) in terms of the distance between the target and the localization point estimated from the surrogates (|TMD|), the average of respiratory motion for the surrogates and the target (|aRM|), and the number of fiducial markers used for estimating the target (n)., Methods: This study enrolled 17 lung cancer patients who subsequently underwent four fractions of real-time tumor tracking irradiation. Four or five fiducial markers were implanted around the lung tumor. The three-dimensional (3D) distance between the tumor and markers was at maximum 58.7 mm. One of the markers was used as the target (Pt), and those markers with a 3D |TMDn| ≤ 58.7 mm at end-exhalation were then selected. The estimated target position (Pe) was calculated from a localization point consisting of one to three markers except Pt. Respiratory motion for Pt and Pe was defined as the root mean square of each displacement, and |aRM| was calculated from the mean value. TLE was defined as the root mean square of each difference between Pt and Pe during the monitoring of each fraction. These procedures were performed repeatedly using the remaining markers. To provide the best guidance on the answer with n and |TMD|, fiducial markers with a 3D |aRM ≥ 10 mm were selected. Finally, a total of 205, 282, and 76 TLEs that fulfilled the 3D |TMD| and 3D |aRM| criteria were obtained for n = 1, 2, and 3, respectively. Multiple regression analysis (MRA) was used to evaluate TLE as a function of |TMD| and |aRM| in each n., Results: |TMD| for n = 1 was larger than that for n = 3. Moreover, |aRM| was almost constant for all n, indicating a similar scale for the marker's motion near the lung tumor. MRA showed that |aRM| in the left-right direction was the major cause of TLE; however, the contribution made little difference to the 3D TLE because of the small amount of motion in the left-right direction. The TLE calculated from the MRA ((MRA)TLE) increased as |TMD| and |aRM| increased and adversely decreased with each increment of n. The median 3D (MRA)TLE was 2.0 mm (range, 0.6-4.3 mm) for n = 1, 1.8 mm (range, 0.4-4.0 mm) for n = 2, and 1.6 mm (range, 0.3-3.7 mm) for n = 3. Although statistical significance between n = 1 and n = 3 was observed in all directions, the absolute average difference and the standard deviation of the (MRA)TLE between n = 1 and n = 3 were 0.5 and 0.2 mm, respectively., Conclusions: A large |TMD| and |aRM| increased the differences in TLE between each n; however, the difference in 3D (MRA)TLEs was, at most, 0.6 mm. Thus, the authors conclude that it is acceptable to continue fiducial marker-based radiotherapy as long as |TMD| is maintained at ≤58.7 mm for a 3D |aRM|  ≥  10 mm.

The purpose of this study was to investigate whether a new O-ring design radiotherapy delivery system has advantages in radiotherapy planning for skull-base tumors. Twenty-five patients with skull-base tumors were included in this study. Two plans were made using conventional (Plan A) or new (Plan B) techniques. Plan A consisted of four dynamic conformal arcs (DCAs): two were horizontal, and the other two were from cranial directions. Plan B was created by converting horizontal arcs to those from caudal directions making use of the O-ring design radiotherapy system. The micromultileaf collimators were fitted to cover at least 99% of the planning target volume with prescribed doses, 90% of the dose at the isocenter. The two plans were compared in terms of target homogeneity, conformity, and irradiated volume of normal tissues, using a two-sided paired t-test. For evaluation regarding target coverage, the homogeneity indices defined by the International Commission on Radiation Units and Measurements 83 were 0.099 ± 0.010 (mean ± standard deviation) and 0.092 ± 0.010, the conformity indices defined by the Radiation Therapy Oncology Group were 1.720 ± 0.249 and 1.675 ± 0.239, and the Paddick's conformity indices were 0.585 ± 0.078 and 0.602 ± 0.080, in Plans A and B, respectively. For evaluation of irradiated normal tissue, the Paddick's gradient indices were 3.118 ± 0.283 and 2.938 ± 0.263 in Plans A and B, respectively. All of these differences were statistically significant (p-values < 0.05). The mean doses of optic nerves, eyes, brainstem, and hippocampi were also significantly lower in Plan B. The DCA technique from caudal directions using the new O-ring design radiotherapy system can improve target homogeneity and conformity compared with conventional DCA techniques, and can also decrease the volume of surrounding normal tissues that receives moderate doses.

Purpose: To quantify the predictive uncertainty in infrared (IR)-marker-based dynamic tumor tracking irradiation (IR Tracking) with Vero4DRT (MHI-TM2000) for lung cancer using logfiles., Methods: A total of 110 logfiles for 10 patients with lung cancer who underwent IR Tracking were analyzed. Before beam delivery, external IR markers and implanted gold markers were monitored for 40 s with the IR camera every 16.7 ms and with an orthogonal kV x-ray imaging subsystem every 80 or 160 ms. A predictive model [four-dimensional (4D) model] was then created to correlate the positions of the IR markers (PIR) with the three-dimensional (3D) positions of the tumor indicated by the implanted gold markers (Pdetect). The sequence of these processes was defined as 4D modeling. During beam delivery, the 4D model predicted the future 3D target positions (Ppredict) from the PIR in real-time, and the gimbaled x-ray head then tracked the target continuously. In clinical practice, the authors updated the 4D model at least once during each treatment session to improve its predictive accuracy. This study evaluated the predictive errors in 4D modeling (E4DM) and those resulting from the baseline drift of PIR and Pdetect during a treatment session (EBD). E4DM was defined as the difference between Ppredict and Pdetect in 4D modeling, and EBD was defined as the mean difference between Ppredict calculated from PIR in updated 4D modeling using (a) a 4D model created from training data before the model update and (b) an updated 4D model created from new training data., Results: The mean E4DM was 0.0 mm with the exception of one logfile. Standard deviations of E4DM ranged from 0.1 to 1.0, 0.1 to 1.6, and 0.2 to 1.3 mm in the left-right (LR), anterior-posterior (AP), and superior-inferior (SI) directions, respectively. The median elapsed time before updating the 4D model was 13 (range, 2-33) min, and the median frequency of 4D modeling was twice (range, 2-3 times) per treatment session. EBD ranged from -1.0 to 1.0, -2.1 to 3.3, and -2.0 to 3.5 mm in the LR, AP, and SI directions, respectively. EBD was highly correlated with BDdetect in the LR (R = -0.83) and AP directions (R = -0.88), but not in the SI direction (R = -0.40). Meanwhile, EBD was highly correlated with BDIR in the SI direction (R = -0.67), but not in the LR (R = 0.15) or AP (R = -0.11) direction. If the 4D model was not updated in the presence of intrafractional baseline drift, the predicted target position deviated from the detected target position systematically., Conclusions: Application of IR Tracking substantially reduced the geometric error caused by respiratory motion; however, an intrafractional error due to baseline drift of >3 mm was occasionally observed. To compensate for EBD, the authors recommend checking the target and IR marker positions constantly and updating the 4D model several times during a treatment session.

Objectives: Salvage radiotherapy is the only curative treatment for patients with prostate cancer showing biochemical progression after radical prostatectomy. In this study, we evaluated the clinicopathological parameters that influence the outcome of salvage radiotherapy., Methods: Medical records of 49 patients who underwent salvage radiotherapy after radical prostatectomy from 1997 to 2008 at the Graduate School of Medicine, Kyoto University, were retrospectively reviewed. Radiotherapy was carried out with 66 Gy on the prostatic bed., Results: Biochemical progression-free survival after salvage radiotherapy at 2, 5 and 7 years was 51.0%, 42.2% and 42.2%, respectively. Significant parameters predicting biochemical progression after salvage radiotherapy by Cox regression analysis were prostatectomy Gleason score sum ≥ 8 (hazard ratio 0.08; 95% confidence interval 0.03-0.22; P=0.001), prostate-specific antigen nadir after radical prostatectomy ≥ 0.04 ng/mL (hazard ratio 0.30; 95% confidence interval 0.13-0.69; P=0.005) and negative surgical margin (hazard ratio 0.28; 95% confidence interval 0.12-0.70; P=0.006). When the patients were subgrouped by these risk factors, the 5-year progression-free survival rates after salvage radiotherapy were 77.8%, 50.0% and 6.7% in patients with 0, 1 and ≥ 2 predictors, respectively., Conclusion: In order to discriminate favorable candidates for salvage radiotherapy, Gleason score of prostatectomy, prostate-specific antigen nadir after prostatectomy and positive surgical margin represent independent predictors. Thus, progression-free survival might be more precisely predicted according to the presence/absence of these risk factors. The significance of this risk classification should be confirmed by large prospective studies., (© 2013 The Japanese Urological Association.)

Purpose: To present the dosimetric characterization of a multileaf collimator (MLC) for a new four-dimensional image-guided radiotherapy system with a gimbaled x-ray head, MHI-TM2000., Methods: MHI-TM2000 has an x-ray head composed of an ultrasmall linear accelerator guide and a system-specific MLC. The x-ray head can rotate along the two orthogonal gimbals (pan and tilt rotations) up to +/- 2.5 degrees, which swings the beam up to +/- 41.9 mm in each direction from the isocenter on the isocenter plane perpendicular to the beam. The MLC design is a single-focus type, has 30 pairs of 5 mm thick leaves at the isocenter, and produces a maximum field size of 150 x 150 mm2. Leaf height and length are 110 and 260 mm, respectively. Each leaf end is circular, with a radius of curvature of 370 mm. The distance that each leaf passes over the isocenter is 77.5 mm. Radiation leakage between adjacent leaves is minimized by an interlocking tongue-and-groove (T&G) arrangement with the height of the groove part 55 mm. The dosimetric characterizations including field characteristics, leaf position accuracy, leakage, and T&G effect were evaluated using a well-commissioned 6 MV photon beam, EDR2 films (Kodak, Rochester, NY), and water-equivalent phantoms. Furthermore, the field characteristics and leaf position accuracy were evaluated under conditions of pan or tilt rotation., Results: The differences between nominal and measured field sizes were within +/- 0.5 mm. Although the penumbra widths were greater with wider field size, the maximum width was < 5.5 mm even for the fully opened field. Compared to the results of field characteristics without pan or tilt rotation, the variation in field size, penumbra width, flatness, and symmetry was within +/- 1 mm/l% at the maximum pan or tilt rotational angle. The leaf position accuracy was 0.0 +/- 0.1 mm, ranging from -0.3 to 0.2 mm at four gantry angles of 0 degrees, 90 degrees, 180 degrees, and 270 degrees with and without pan or tilt rotation. The interleaf leakage was up to 0.21%, whereas the intraleaf leakage was < 0.12%. T&G decreased the doses by 10.7%, on average., Conclusions: This study demonstrated that MHI-TM2000 has the capability for high leaf position accuracy and low leakage, leading to highly accurate intensity-modulated radiotherapy delivery. Furthermore, substantial changes in the dosimetric data on field characteristics and leaf position accuracy were not observed even at the maximum pan or tilt rotation.

Background and Purpose: We verified the propriety of our systematic error reduction strategy by means of a computer simulation based on our data of position error with a prone fixation device for prostate IMRT., Materials and Methods: Computer simulations of the off-line correction method for systematic setup errors based on the portal imaging taken on the first several days of the treatment session were performed. Using the computer simulations, an optimal number of portal images were evaluated for the SD value, from 0.5 mm to 1.5 mm at a 0.25 mm interval, and the respective required setup margins were calculated., Results: The value of systematic error was reduced as the frequency of data obtained increased. Moreover, the reduction rate was so remarkable that random error was large.

Purpose: To develop and evaluate a new four-dimensional image-guided radiotherapy system, which enables precise setup, real-time tumor tracking, and pursuit irradiation., Methods and Materials: The system has an innovative gimbaled X-ray head that enables small-angle (+/-2.4 degrees ) rotations (pan and tilt) along the two orthogonal gimbals. This design provides for both accurate beam positioning at the isocenter by actively compensating for mechanical distortion and quick pursuit of the target. The X-ray head is composed of an ultralight C-band linear accelerator and a multileaf collimator. The gimbaled X-ray head is mounted on a rigid O-ring structure with an on-board imaging subsystem composed of two sets of kilovoltage X-ray tubes and flat panel detectors, which provides a pair of radiographs, cone beam computed tomography images useful for image guided setup, and real-time fluoroscopic monitoring for pursuit irradiation., Results: The root mean square accuracy of the static beam positioning was 0.1 mm for 360 degrees of O-ring rotation. The dynamic beam response and positioning accuracy was +/-0.6 mm for a 0.75 Hz, 40-mm stroke and +/-0.4 mm for a 2.0 Hz, 8-mm stroke. The quality of the images was encouraging for using the tomography-based setup. Fluoroscopic images were sufficient for monitoring and tracking lung tumors., Conclusions: Key functions and capabilities of our new system are very promising for precise image-guided setup and for tracking and pursuit irradiation of a moving target.

Background: Centrally located lung tumours present a challenge because of their tendency to exhibit symptoms such as airway obstruction, atelectasis, and bleeding. Surgical resection of these tumours often requires sacrificing the lungs, making definitive radiotherapy the preferred alternative to avoid pneumonectomy. However, the proximity of these tumours to mediastinal organs at risk increases the potential for severe adverse events. To mitigate this risk, we propose a dual-method approach: deep inspiration breath-hold (DIBH) radiotherapy combined with adaptive radiotherapy. The aim of this single-centre, single-arm phase II study is to investigate the efficacy and safety of DIBH daily online adaptive radiotherapy. Methods: Patients diagnosed with centrally located lung tumours according to the International Association for the Study of Lung Cancer recommendations, are enrolled and subjected to DIBH daily online adaptive radiotherapy. The primary endpoint is the one-year cumulative incidence of grade 3 or more severe adverse events, as classified by the Common Terminology Criteria for Adverse Events (CTCAE v5.0). Discussion: Delivering definitive radiotherapy for centrally located lung tumours presents a dilemma between ensuring optimal dose coverage for the planning target volume and the associated increased risk of adverse events. DIBH provides measurable dosimetric benefits by increasing the normal lung volume and distancing the tumour from critical mediastinal organs at risk, leading to reduced toxicity. DIBH adaptive radiotherapy has been proposed as an adjunct treatment option for abdominal and pelvic cancers. If the application of DIBH adaptive radiotherapy to centrally located lung tumours proves successful, this approach could shape future phase III trials and offer novel perspectives in lung tumour radiotherapy. Trial registration. Registered at the Japan Registry of Clinical Trials (jRCT; https://jrct.niph.go.jp/); registration number: jRCT1052230085 (https://jrct.niph.go.jp/en-latest-detail/jRCT1052230085). [ABSTRACT FROM AUTHOR]

Background: This study analyzed the impact of the coronavirus disease 2019 (COVID‐19) pandemic on radiotherapy delivery in Japan using a high‐quality Japanese national database based on universal health coverage. Methods: We performed a retrospective observational study using National Database of Health Insurance Claims and Specific Health Checkups of Japan open data focused on radiotherapy between fiscal year (FY) 2019 and FY2020 and the number of COVID‐19 cases from the Ministry of Health, Labour, and Welfare. We statistically analyzed the relationship between the number of COVID‐19 cases and the number of radiotherapy deliveries in Japan as a whole and by prefecture. Results: The total number of external beam radiotherapy (EBRT) fractions was 4,472,140 in FY2019 and 4,227,673 in FY2020 (−5.8%). EBRT courses were 250,395 in FY2019 and 240,329 in FY2020 (−4.0%), stereotactic radiotherapy courses were 27,619 in FY2019 and 31,786 in FY2020 (+15.1%), and single‐fraction palliative radiotherapy courses were 4124 in FY2019 and 5255 in FY2020 (+21.5%). The total number of breast and prostate hypofractionated radiotherapy (HFRT) fractions was 155,773 and 48,188 in FY2019, and 200,256 and 84,230 in FY2020 (+28.6% and +74.8%), respectively. In the Pearson correlation analysis, EBRT fractions were lower, and breast HFRT fractions were higher in prefectures with more COVID‐19 cases. Conclusions: Overall, radiotherapy delivery in Japan was relatively stable after the pandemic, with an increase in HFRT. Also, EBRT fractions decreased, and breast HFRT were more likely to be used in prefectures with more COVID‐19 cases. [ABSTRACT FROM AUTHOR]

Background: Resectable pancreatic cancer (RPC) is potentially resectable on admission, and the impact of neoadjuvant therapy on these tumors is controversial. Moreover, the safety and efficacy of neoadjuvant chemoradiotherapy with moderately hypofractionated intensity‐modulated radiation therapy (NACIMRT) for RPC have not been studied. Here, we conducted a phase II study to evaluate the safety and efficacy of hypofractionated NACIMRT for RPC. Methods: A total of 54 RPC patients were enrolled and treated according to the study protocol. We used moderately hypofractionated (45 Gy in 15 fractions) IMRT with gemcitabine to shorten the duration of radiotherapy and reduce gastrointestinal toxicity. The primary endpoint was overall survival (OS), and we subsequently analyzed the microscopically margin‐negative resection (R0) rate, disease‐free survival (DFS), and histologic effects and safety of NACIMRT. Results: Median OS for the cohort was 40.0 months. Forty‐two patients (77.8%) underwent pancreatectomy after NACIMRT. Median DFS was 20.3 months. The R0 resection rate was 95.2% (40/42) per protocol and 85.2% (46/54) for the cohort. There were no intervention‐related deaths during the study period. Local treatment response, as assessed by the CAP classification, showed no residual tumor in 4.8% of patients. Overall, 23.9% of patients experienced CTCAE grade 3 or 4 during NACIMRT. Adjuvant therapy was initiated in 88% of patients undergoing resection. Postoperative complications grade ≥3b on the Clavien–Dindo scale occurred in 4.8% of patients. CA19‐9 level at enrollment was an independent prognostic factor for OS and DFS. Conclusions: This is the first prospective study of hypofractionated IMRT as neoadjuvant therapy for RPC. Hypofractionated NACIMRT for RPC could be safely introduced with a high induction rate of adjuvant chemotherapy, with an overall survival of 40.0 months. [ABSTRACT FROM AUTHOR]

Purpose: The Medical Physics Working Group of the Radiation Therapy Study Group at the Japan Clinical Oncology Group is currently developing a virtual audit system for intensity‐modulated radiation therapy dosimetry credentialing. The target dosimeters include films and array detectors, such as ArcCHECK (Sun Nuclear Corporation, Melbourne, Florida, USA) and Delta4 (ScandiDos, Uppsala, Sweden). This pilot study investigated the feasibility of our virtual audit system using previously acquired data. Methods: We analyzed 46 films (32 and 14 in the axial and coronal planes, respectively) from 29 institutions. Global gamma analysis between measured and planned dose distributions used the following settings: 3%/3 mm criteria (the dose denominator was 2 Gy), 30% threshold dose, no scaling of the datasets, and 90% tolerance level. In addition, 21 datasets from nine institutions were obtained for array evaluation. Five institutions used ArcCHECK, while the others used Delta4. Global gamma analysis was performed with 3%/2 mm criteria (the dose denominator was the maximum calculated dose), 10% threshold dose, and 95% tolerance level. The film calibration and gamma analysis were conducted with in‐house software developed using Python (version 3.9.2). Results: The means ± standard deviations of the gamma passing rates were 99.4 ± 1.5% (range, 92.8%–100%) and 99.2 ± 1.0% (range, 97.0%–100%) in the film and array evaluations, respectively. Conclusion: This pilot study demonstrated the feasibility of virtual audits. The proposed virtual audit system will contribute to more efficient, cheaper, and more rapid trial credentialing than on‐site and postal audits; however, the limitations should be considered when operating our virtual audit system. [ABSTRACT FROM AUTHOR]

Background: Management of pelvic node‐positive prostate cancer has been challenging and controversial. We conducted a study to evaluate the outcomes of whole‐pelvic (WP) simultaneous integrated boost (SIB) intensity‐modulated radiation therapy (IMRT) combined with androgen deprivation therapy (ADT). Methods: A total of 67 consecutive patients with cT1c‐4N1M0 prostate cancer were definitively treated by WP SIB‐IMRT. Neoadjuvant ADT (median: 8.3 months) was administered in all cases. WP SIB‐IMRT was designed to simultaneously deliver 78, 66.3, and 58.5 Gy in 39 fractions to the prostate plus seminal vesicles, metastatic lymph nodes (LNs), and the pelvic LN region, respectively. Adjuvant ADT (median: 24.7 months) was administered in 66 patients. Results: The median follow‐up period was 81.6 months (range: 30.5–160.7). Biochemical relapse‐free, overall, and prostate cancer‐specific survival rates at 10 years were 59.8%, 79.6%, and 86.3%, respectively. Loco‐regional recurrence was not observed. Being in International Society of Urological Pathology grade group 5 and having a posttreatment detectable nadir prostate‐specific antigen (PSA) level (≥0.010 ng/ml) were significantly associated with worse prostate cancer‐specific survival and progression of castration resistance. The 10‐year cumulative incidence rates of grade 2 and 3 late toxicities were, respectively, 1.5% and 0% for genitourinary, 0% and 1.5% for gastrointestinal events. No grade 4 acute or late toxicities were observed. Conclusions: WP SIB‐IMRT can be safely administered to patients with pelvic node‐positive prostate cancer. Since grade group 5 and detectable nadir PSA levels are risks for castration resistance, we may need to increase the intensity of treatment for such cases. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this study was to demonstrate the potential utility of cone‐beam computed tomography (CBCT)‐guided online adaptive radiotherapy (ART) under end‐exhalation breath‐hold (EE‐BH) conditions for pancreatic cancer (PC). Methods: Eleven PC patients who underwent 15‐fraction volumetric‐modulated arc therapy under EE‐BH conditions were included. Planning CT images and daily 165 CBCT images were imported into a dedicated treatment planning system. The prescription dose was set to 48 Gy in 15 fractions. The reference plan was automatically generated along with predefined clinical goals. After segmentation was completed on CBCT images, two different plans were generated: One was an adapted (ADP) plan in which re‐optimization was performed on the anatomy of the day, and the other was a scheduled (SCH) plan, which was the same as the reference plan. The dose distributions calculated using the synthetic CT created from both planning CT and CBCT were compared between the two plans. Independent calculation‐based quality assurance was also performed for the ADP plans, with a gamma passing rate of 3%/3 mm. Results: All clinical goals were successfully achieved during the reference plan generation. Of the 165 sessions, gross tumor volume D98% and clinical target volume D98% were higher in 100 (60.1%) and 122 (74.0%) ADP fractions. In each fraction, the V3 Gy < 1 cm3 of the stomach and duodenum was violated in 47 (28.5%) and 48 (29.1%), respectively, of the SCH fractions, whereas no violations were observed in the ADP fractions. There were statistically significant differences in the dose–volume indices between the SCH and ADP fractions (p < 0.05). The gamma passing rates were above 95% in all ADP fractions. Conclusions: The CBCT‐guided online ART under EE‐BH conditions successfully reduced the dose to the stomach and duodenum while maintaining target coverage. [ABSTRACT FROM AUTHOR]

A longitudinal online questionnaire survey on the impact of coronavirus disease 2019 (COVID-19) on the operation of radiotherapy departments in Japan was conducted. Approximately 26.1–70.9% of the radiotherapy departments participated, and their responses were collected in May, July and November 2020, and February and June 2021. The survey results revealed that while the number of patients receiving radiotherapy decreased in 41.2% and 30.7% of institutions in May 2020 and June 2021, respectively, it increased in 4% and 16.8% of institutions in May 2020 and June 2021, respectively. There were a few institutions limiting or postponing patient treatments in June 2021. The hypofractionated regimen was used more during the pandemic than during the pre-pandemic period, particularly for the treatment of breast and prostate cancers as well as for palliation. Infection control measures for patients and staff were followed. Approximately 20% of the respondent institutions had cases of patients with COVID-19 infection receiving radiotherapy. Most institutions encountered challenges in the continuous provision of radiotherapy for patients with COVID-19. In conclusion, COVID-19 had a multifaceted impact on the operations of radiotherapy departments in Japan. Further follow-up and analysis are warranted to understand the long-term impact of COVID-19 on radiotherapy. [ABSTRACT FROM AUTHOR]

Background: Etoposide plus cisplatin (EP) combined with concurrent accelerated hyperfractionated thoracic radiotherapy (AHTRT) is the standard treatment strategy for unresectable limited‐disease (LD) small cell lung cancer (SCLC), which has remained unchanged for over two decades. Based on a previous study that confirmed the non‐inferiority of amrubicin (AMR) plus cisplatin (AP) when compared with EP for extensive‐disease (ED) SCLC, we have previously conducted a phase I study assessing AP with concurrent TRT (2 Gy/time, once daily, 50 Gy in total) for LD‐SCLC therapy. Our findings revealed that AP with concurrent TRT could prolong overall survival to 39.5 months with manageable toxicities. Therefore, we plan to conduct a phase I study to investigate and determine the effect of AP combined with AHTRT, recommended dose (RD), maximum tolerated dose (MTD), and dose‐limiting toxicity (DLT) of AP in patients with LD‐SCLC. Methods: Treatment‐naive patients with LD‐SCLC, age between 20 and 75 years, who had a performance status of 0 or 1 and adequate organ functions will be enrolled. For chemotherapy, cisplatin 60 mg/m2/day (day 1) and AMR (day 1 to 3) will be administered with AHTRT (1.5 Gy/time, twice daily, 45 Gy in total). The initial AMR dose is set to 25 mg/m2/day. RD and MTD will be determined by evaluating toxicities. Discussion: Based on our previous study, the initial dose of AMR 25 mg/m2 is expected to be tolerated and acceptable. Here, we aim to determine whether treatment with AP and concurrent AHTRT would be an optimal choice with manageable toxicities for LD‐SCLC. [ABSTRACT FROM AUTHOR]

The lung volume receiving low-dose irradiation has been reported to increase in volumetric-modulated arc radiotherapy (VMAT) compared with three-dimensional conformal radiotherapy (3DCRT) for thoracic esophageal cancer, which raises concerns regarding radiation pneumonitis (RP) risk. This single institutional retrospective cohort study aimed to explore whether VMAT for thoracic esophageal cancer was associated with RP. Our study included 161 patients with thoracic esophageal cancer, of whom 142 were definitively treated with 3DCRT and 39 were treated with VMAT between 2008 and 2018. Radiotherapy details, dose–volume metrics, reported RP risk factors and RP incidence were collected. The RP risk factors were assessed via multivariate analysis. Dose–volume analysis showed that VMAT delivered more conformal dose distributions to the target volume (P  < 0.001) and reduced V30 Gy of heart (57% vs 41%, P  < 0.001) but increased V5 Gy (54% vs 41%, P  < 0.001) and V20 Gy (20% vs 17%, P  = 0.01) of lungs compared with 3DCRT. However, the 1-year incidence rates of RP did not differ between the two techniques (11.3% in 3DCRT vs 7.7% in VMAT, P  = 0.53). The multivariate analysis suggested that the presence of interstitial lung disease (ILD) (P  = 0.01) and V20 Gy of lungs ≥20% (P  = 0.008) were associated with RP. Conclusively, VMAT increased the lung volume receiving low to middle doses irradiation, although this might not be associated with RP. Further studies are needed to investigate the effect of using VMAT for delivering conformal dose distributions on RP. [ABSTRACT FROM AUTHOR]

Purpose: Patients undergoing radiotherapy often have their skin marked. Previous studies on skin markings examined the durability and physical effects of the markings, but no study has focused on patients' emotional experiences toward the markings. This study aimed to clarify how patients undergoing radiotherapy feel about skin markings, as well as factors that affect patients' emotional experiences. Patients and Methods: We conducted a cross-sectional study using a self-administered questionnaire and medical records. Participants were patients aged ≥ 20 years undergoing cancer radiotherapy at a designated cancer care hospital. The primary outcome was the level of uncomfortable emotions toward skin markings, and the secondary outcome was the level of favorable ratings on skin markings. To examine factors related to uncomfortable emotions, ordinal logistic regression analysis was performed. Results: Questionnaire forms were distributed to 153 patients, and responses were collected from 132 (86%). Among 108 patients included in the analysis, 56% (59/105, excluding 3 who did not answer this question) responded that they were uncomfortable with skin markings. The proportion of patients who favorably rated skin markings was 63% (59/93, excluding 15 who did not answer this question). No factors were significantly associated with the primary outcome. Conclusion: Many patients accepted skin markings with resignation, as they understood the necessity of the markings in their treatment. Medical staff should understand the emotional experiences of patients toward skin markings and take sufficient care to ensure that they are provided with explanations, including the impact of skin markings on their daily lives, as well as a sense of security that treatment is being performed in a precise manner. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this planning study was to develop an acceptable technique for highly hypofractionated intensity-modulated radiation therapy using simultaneous integrated boost technique (SIB-hHF-RT) for nonmetastatic National Comprehensive Cancer Network high-risk prostate cancer. Materials and methods: We created SIB-hHF-RT plans for 14 nonmetastatic prostate cancer patients with MRI-detectable intraprostatic lesions (IPLs) and without intestines locating close to the seminal vesicle and prostate. We prescribed 57 Gy for IPLs and 54 Gy for the remainder of planning target volume (PTV) in 15 fractions. The IPLs were contoured based on magnetic resonance imaging, and PTV was generated by adding 6–8-mm margins to the clinical target volume. For the dose-volume constraints of organs at risk (OARs), the same constraints as 54 Gy plans were used so as not to increase the toxicity. Results: All created plans fulfilled the dose-volume constraints of all targets and OARs. The median estimated beam-on time was 108.5 s. For patient-specific quality assurance, the global gamma passing rates (3%/2 mm) with 10% dose threshold criteria were greater than 93% in all cases and greater than 95% in 11 cases. Conclusion: SIB-hHF-RT plans were developed that fulfill the acceptable dose-volume constraints and pass patient-specific quality assurance. We believe these plans can be applied to selected patients with nonmetastatic prostate cancer. [ABSTRACT FROM AUTHOR]

Background: Borderline resectable pancreatic cancer (BRPC) is a category of pancreatic cancer that is anatomically widely spread, and curative resection is uncommon with upfront surgery. Intensity-modulated radiation therapy (IMRT) is a form of radiation therapy that delivers precise radiation to a tumor while minimizing the dose to surrounding normal tissues. Here, we conducted a phase 2 study to estimate the curability and efficacy of neoadjuvant chemoradiotherapy using IMRT (NACIMRT) for patients with BRPC with arterial abutment (BRPC-A).Methods: A total of 49 BRPC-A patients were enrolled in this study and were treated at our hospital according to the study protocol between June 2013 and March 2021. The primary endpoint was microscopically margin-negative resection (R0) rates and we subsequently analyzed safety, histological effect of the treatment as well as survivals among patients with NACIMRT.Results: Twenty-nine patients (59.2%) received pancreatectomy after NACIMRT. The R0 rate in resection patients was 93.1% and that in the whole cohort was 55.1%. No mortality was encountered. Local therapeutic effects as assessed by Evans classification showed good therapeutic effect (Grade 1, 3.4%; Grade 2a, 31.0%; Grade 2b, 48.3%; Grade 3, 3.4%; Grade 4, 3.4%). Median disease-free survival was 15.5 months. Median overall survival in the whole cohort was 35.1 months. The only independent prognostic pre-NACIMRT factor identified was serum carbohydrate antigen 19-9 (CA19-9) > 400 U/ml before NACIMRT.Conclusions: NACIMRT showed preferable outcome without significant operative morbidity for BRPC-A patients. NACIMRT contributes to good local tumor control, but a high initial serum CA19-9 implies poor prognosis even after neoadjuvant treatment.Trial Registration: UMIN-CTR Clinical Trial: https://upload.umin.ac.jp/cgi-open-bin/ctr_e/ctr_view.cgi?recptno=R000011776 Registration number: UMIN000010113. Date of first registration: 01/03/2013. [ABSTRACT FROM AUTHOR]

Background: The aim of this study was to evaluate the long-term efficacy and safety of whole pelvic intensity-modulated radiation therapy with a simultaneous-integrated boost (WP-SIB-IMRT) for locally advanced prostate cancer (LAPCa). Methods: All patients with cT3–4N0M0 prostate cancer treated with WP-SIB-IMRT between February 2006 and September 2009 at our institution were analyzed retrospectively. The prescribed dose was 78 Gy to the prostate and 58.5 Gy to the prophylactic pelvic lymph nodal area in 39 fractions delivered using the simultaneous-integrated boost technique. All patients received short-term neoadjuvant androgen-deprivation therapy alone (median 8.3 months). Propensity-score matching (PSM) analysis was performed to evaluate the additional benefit of prophylactic whole pelvic radiation therapy (WPRT), using the cohort of 203 LAPCa patients treated with prostate-only IMRT (PO-IMRT). Results: In total, 47 consecutive patients were analyzed. The median estimated risk of pelvic lymph node involvement was 57.5%. The median follow-up period was 10.5 years. The 10 year prostate cancer-specific survival and biochemical failure (BF) rates were 92.2 and 54.8%, respectively. The 10 year cumulative incidence rates of ≥ grade 2 late genitourinary and gastrointestinal toxicities were 21.6 and 17.2%, respectively. From a total of 250 patients, PSM analysis identified 76 patients with similar characteristics, and no significant difference in BF rates was observed between WP-SIB-IMRT and PO-IMRT cohorts (p = 0.261). Conclusions: WP-SIB-IMRT for LAPCa was safe over long-term observation, although no clear benefit of WPRT was observed among our small and highly selected cohort. Regarding the additional efficacy of WPRT, further investigations are needed. [ABSTRACT FROM AUTHOR]

Purpose: To predict radiation pneumonitis (RP) grade 2 or worse after lung stereotactic body radiation therapy (SBRT) using dose‐based radiomic (dosiomic) features. Methods: This multi‐institutional study included 247 early‐stage nonsmall cell lung cancer patients who underwent SBRT with a prescribed dose of 48–70 Gy at an isocenter between June 2009 and March 2016. Ten dose–volume indices (DVIs) were used, including the mean lung dose, internal target volume size, and percentage of entire lung excluding the internal target volume receiving greater than x Gy (x = 5, 10, 15, 20, 25, 30, 35, and 40). A total of 6,808 dose‐segmented dosiomic features, such as shape, first order, and texture features, were extracted from the dose distribution. Patients were randomly partitioned into two groups: model training (70%) and test datasets (30%) over 100 times. Dosiomic features were converted to z‐scores (standardized values) with a mean of zero and a standard deviation (SD) of one to put different variables on the same scale. The feature dimension was reduced using the following methods: interfeature correlation based on Spearman's correlation coefficients and feature importance based on a light gradient boosting machine (LightGBM) feature selection function. Three different models were developed using LightGBM as follows: (a) a model with ten DVIs (DVI model), (b) a model with the selected dosiomic features (dosiomic model), and (c) a model with ten DVIs and selected dosiomic features (hybrid model). Suitable hyperparameters were determined by searching the largest average area under the curve (AUC) value in the receiver operating characteristic curve (ROC–AUC) via stratified fivefold cross‐validation. Each of the final three models with the closest the ROC–AUC value to the average ROC–AUC value was applied to the test datasets. The classification performance was evaluated by calculating the ROC–AUC, AUC in the precision–recall curve (PR–AUC), accuracy, precision, recall, and f1‐score. The entire process was repeated 100 times with randomization, and 100 individual models were developed for each of the three models. Then the mean value and SD for the 100 random iterations were calculated for each performance metric. Results: Thirty‐seven (15.0%) patients developed RP after SBRT. The ROC–AUC and PR–AUC values in the DVI, dosiomic, and hybrid models were 0.660 ± 0.054 and 0.272 ± 0.052, 0.837 ± 0.054 and 0.510 ± 0.115, and 0.846 ± 0.049 and 0.531 ± 0.116, respectively. For each performance metric, the dosiomic and hybrid models outperformed the DVI models (P < 0.05). Texture‐based dosiomic feature was confirmed as an effective indicator for predicting RP. Conclusions: Our dose‐segmented dosiomic approach improved the prediction of the incidence of RP after SBRT. [ABSTRACT FROM AUTHOR]

• The rise and downfall of a newly-developed radiotherapy system is reviewed. • The machine was a gimbaled-head system, designed for flexible irradiation with robust structures. • It provided novel dynamic tumor tracking with real-time monitoring; and dynamic wavearc. • These could provide advantages for clinical applications and clinical trials are underway. A gimbaled–head radiotherapy device was developed by industry-academic collaborations, with a concept of robust structures whilst maintaining high flexibilities, and its clinical application started in 2008. The unique structures with multi-image guidance functions initiated 2 new treatment modalities. One is dynamic tumor tracking radiotherapy with real time monitoring (DTTRM), which enables 4-D radiotherapy without prolongation of radiotherapy treatment time. This treatment has become clinically feasible for stereotactic body radiotherapy (SBRT) of lung cancers and liver tumors, and intensity-modulated radiotherapy (IMRT) for pancreatic cancers. The second one is Dynamic WaveArc therapy (DWA), the non-coplanar versatility of the SBRT system by combining the gantry-ring synchronized rotation with dynamic multileaf collimator optimization. DWA opens the possibility to create patient-individualized treatment plans, allowing additional flexibility in organ at risk sparing while preserving dosimetric robust delivery. The clinical usefulness of the DWA has been preliminary shown for those tumors in the prostate, breast and skull base. Prospective clinical trials are under way with a support of the national funding of Japan for DTTRM and DWA, respectively. Marketing of the system was terminated in 2016 due to a commercial decision. However, lessons can be learned from the development process of this device that might be useful for those who have interests in new technologies and clinical applications in radiation oncology. This review article aims to summarize the developments and achievements of a gimbaled-head radiotherapy device with a focus on DTTRM and DWA. [ABSTRACT FROM AUTHOR]

The purpose of this study was to assess the positional repeatability of internal and external markers among multiple breath-hold (BH) sessions and evaluate the positional variation of these markers within BH sessions for volumetric-modulated arc therapy (VMAT) for pancreatic cancer patients. A total of 13 consecutive pancreatic cancer patients with an internal marker were enrolled. Single full-arc coplanar VMAT was delivered under end-exhalation BH conditions while monitoring the internal marker with kilovoltage (kV) X-ray fluoroscopy. Positional repeatability of the internal and external markers was determined by the difference between the reference and zero position in all BH sessions, and positional variation was defined by the displacement from the reference position in each BH session during megavolt beam delivery. The overall positional repeatability was 0.6 ± 1.5 mm in the X-axis for the centroid of the internal marker (CoIM), −0.1 ± 2.2 mm in the Y-axis for the CoIM, and 0.8 ± 2.2 mm for the external marker. The frequency of an internal marker position appearing > 2 mm from the reference position in the Y-axis, despite the external marker position being ≤2 mm from the reference position, ranged from 0.0 to 39.9% for each patient. Meanwhile, the proportion of sessions with positional variation ≤2 mm was 93.2 and 98.7% for the CoIM and external marker, respectively. External marker motion can be used as a surrogate for pancreatic tumor motion during BH-VMAT delivery; however, margins of ~5 mm were required to ensure positional repeatability. [ABSTRACT FROM AUTHOR]

Purpose: To measure the scattered x‐rays of megavoltage (MV) and kilovoltage (kV) beams (MV scatter and kV scatter, respectively) on the orthogonal kV imaging subsystems of Vero4DRT. Methods: Images containing MV‐ and kV‐scatter from another source only (i.e., MV‐ and kV‐scatter maps) were acquired for each investigated flat panel detector. The reference scatterer was a water‐equivalent cuboid phantom. The maps were acquired by changing one of the following parameters from the reference conditions while keeping the others fixed: field size: 10.0 × 10.0 cm2; dose rate: 400 MU/min; gantry and ring angles: 0°; kV collimator aperture size at isocenter: 10.0 × 10.0 cm2: tube voltage: 110 kV; and exposure: 0.8 mAs. The average pixel values of MV‐ and kV‐scatter (i.e., the MV‐ and kV‐scatter values) at the center of each map were calculated and normalized to the MV‐scatter value under the reference conditions (MV‐ and kV‐scatter value factor, respectively). In addition, an MV‐ and kV‐scatter correction experiment with intensity‐modulated beams was performed using a phantom with four gold markers (GMs). The ratios between the intensities of the GMs and those of their surroundings were calculated. Results: The measurements showed a strong dependency of the MV‐scatter on the field size and dose rate. The maximum MV‐scatter value factors were 2.0 at a field size of 15.0 × 15.0 cm2 and 2.5 at a dose rate of 500 MU/min. The maximum kV‐scatter value was 0.48 with a fully open kV collimator aperture. In the phantom experiment, the intensity ratios of kV images with MV‐ and kV‐scatter were decreased from the reference ones. After correction of kV‐scatter only, MV‐scatter only, and both MV‐ and kV‐scatter, the intensity ratios gradually improved. Conclusions: MV‐ and kV‐scatter could be corrected by subtracting the scatter maps from the projections, and the correction improved the intensity ratios of the GMs. [ABSTRACT FROM AUTHOR]

Although salvage external-beam radiation therapy (EBRT) is an attractive treatment option for pelvic lymph nodal recurrence (PeNR) in patients with prostate cancer (PCa), limited data are available regarding its long-term efficacy. This study examined the long-term clinical outcomes of patients who underwent salvage pelvic radiation therapy (sPRT) for oligo-recurrent pelvic lymph nodes after definitive EBRT for non-metastatic PCa. Patients who developed PeNR after definitive EBRT and were subsequently treated with sPRT at our institution between November 2007 and December 2015 were retrospectively analyzed. The prescribed dose was 45–50.4 Gy (1.8–2 Gy per fraction) to the upper pelvis, with up to 54–66 Gy (1.8–2 Gy per fraction) for recurrent nodes. Long-term hormonal therapy was used as neoadjuvant and/or adjuvant therapy. The study population consisted of 12 consecutive patients with PeNR after definitive EBRT (median age: 73 years). The median follow-up period was 58.9 months. The 5-year overall survival, PCa-specific survival, biochemical failure-free, clinical failure-free, and castration-resistant PCa-free rates were 82.5, 100.0, 62.3, 81.8, and 81.8%, respectively. No grade 2 or higher sPRT-related late toxicities occurred. In conclusion, more than half of the study patients treated with sPRT had a long-term disease-free status with acceptable morbidities. Moreover, most of the patients maintained hormonal sensitivity. Therefore, this approach may be a promising treatment method for oligo-recurrent pelvic lymph nodes. [ABSTRACT FROM AUTHOR]

This study aimed to investigate the feasibility of independent calculation‐based verification of volumetric‐modulated arc therapy (VMAT)–stereotactic body radiotherapy (SBRT) for patients with lung cancer using a secondary treatment planning system (sTPS). In all, 50 patients with lung cancer who underwent VMAT‐SBRT between April 2018 and May 2019 were included in this study. VMAT‐SBRT plans were devised using the Collapsed‐Cone Convolution in RayStation (primary TPS: pTPS). DICOM files were transferred to Eclipse software (sTPS), which utilized the Eclipse software, and the dose distribution was then recalculated using Acuros XB. For the verification of dose distribution in homogeneous phantoms, the differences among pTPS, sTPS, and measurements were evaluated using passing rates of a dose difference of 5% (DD5%) and gamma index of 3%/2 mm (γ3%/2 mm). The ArcCHECK cylindrical diode array was used for measurements. For independent verification of dose‐volume parameters per the patient's geometry, dose‐volume indices for the planning target volume (PTV) including D95% and the isocenter dose were evaluated. The mean differences (± standard deviations) between the pTPS and sTPS were then calculated. The gamma passing rates of DD5% and γ3%/2 mm criteria were 99.2 ± 2.4% and 98.6 ± 3.2% for pTPS vs. sTPS, 92.9 ± 4.0% and 94.1 ± 3.3% for pTPS vs. measurement, and 93.0 ± 4.4% and 94.3 ± 4.1% for sTPS vs. measurement, respectively. The differences between pTPS and sTPS for the PTVs of D95% and the isocenter dose were −3.1 ± 2.0% and −2.3 ± 1.8%, respectively. Our investigation of VMAT‐SBRT plans for lung cancer revealed that independent calculation‐based verification is a time‐efficient method for patient‐specific quality assurance. [ABSTRACT FROM AUTHOR]

Objectives: This study evaluated the long-term outcomes of intensity-modulated radiation therapy (IMRT) combined with short-term neoadjuvant androgen deprivation therapy (ADT) in patients with intermediate-risk (IR) prostate cancer (PCa). Materials and methods: Patients with IR PCa treated with IMRT at our institution between September 2000 and November 2010 were analyzed retrospectively. The treatment consisted of IMRT (70–78 Gy in 35–39 fractions) combined with 6 months of neoadjuvant ADT. Salvage ADT was initiated when the prostate-specific antigen level was > 4.0 ng/mL Results: In total, 106 consecutive patients with IR PCa (median age: 70 years old) were analyzed. The median follow-up period was 8.0 years. The overall survival, PCa-specific survival, biochemical failure, and clinical failure rates were 99.0%, 100.0%, 6.8%, and 1.9% at 5 years and 89.1%, 100.0%, 11.3%, and 2.9% at 10 years, respectively. Late recurrence (> 5 years) was observed in three cases (2.8%). The cumulative incidence rates of genitourinary (GU) and gastrointestinal (GI) toxicities (grade 2/3) were 10.5% and 5.8% at 5 years, and 14.7% and 5.8% at 10 years, respectively. No patient developed grade 4/5 GU toxicities or grade 3–5 GI toxicities. Conclusion: IMRT at a dose up to 78 Gy combined with short-term neoadjuvant ADT resulted in excellent long-term disease-free outcomes with acceptable morbidities among patients with IR PCa. In addition, the incidence of late recurrence was very low. Further investigation is warranted to confirm our findings. [ABSTRACT FROM AUTHOR]

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 (D 99%) was higher than the near-minimum 3D internal target volume (ITV) dose, whereas the near-maximum 4D GTV dose (D 1%) 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. [ABSTRACT FROM AUTHOR]

Background: To the best of our knowledge, no study has reported mediastinal shift accompanied with obstructive atelectasis due to bulky primary esophageal tumor components treated with adaptive radiotherapy and concurrent chemotherapy.Case Presentation: Here we report the case of a 65-year-old male patient diagnosed with locally advanced thoracic esophageal squamous cell cancer, clinical T4bN1M0, stage IVA. Bronchoscopy and computed tomography (CT) revealed an almost complete obstruction of the lumen of the left bronchus due to compression by bulky primary esophageal tumor components. On admission, the patient presented with dyspnea and decreased arterial oxygen saturation. Chest radiography and CT on admission revealed mediastinal shift with left atelectasis, as opposed to findings from the chest radiography performed 26 days before admission. Because of the patient's overall good condition, we recommended definitive chemoradiotherapy instead of palliative bronchial stent placement. After obtaining the patient's consent, chemoradiotherapy was initiated on the following day and it comprised three-dimensional conformal radiotherapy with 60 Gy in 30 fractions with concurrent administration of cisplatin and 5-fluorouracil. During chemoradiotherapy, tumor location was monitored with cone-beam CT and chest radiography. Chemoradiotherapy on day 8 revealed no evidence of the mediastinal shift. CT simulation was reperformed to adjust the radiotherapy fields to account for geometrical changes induced by the absence of the mediastinal shift. Subsequently, the mediastinal shift and bronchial obstruction did not recur during the course of chemoradiotherapy. The patient completed the planned radiotherapy with concurrent and adjuvant chemotherapy, and no non-hematological grade ≥ 3 adverse events were observed. Complete response was confirmed 7 months after initiating chemoradiotherapy. Currently, no disease recurrence, dysphagia, or respiratory symptoms have been reported at 13 months after initiating chemoradiotherapy.Conclusions: In this study, a bulky primary esophageal tumor caused mediastinal shift due to ipsilateral bronchial obstruction. The close follow-up for monitoring resolution of the mediastinal shift during the course of chemoradiotherapy enabled adequate dose delivery to targets, thus reflecting the geometrical changes induced by the absence of the mediastinal shift. Adaptive radiotherapy technique was crucial for favorable patient outcomes in this challenging clinical situation. [ABSTRACT FROM AUTHOR]

Background: The optimal timing of salvage androgen deprivation therapy (ADT) following definitive radiation therapy for prostate cancer (PCa) is unknown. This study evaluated the efficacy of early initiation of salvage-ADT (S-ADT) based on predetermined timing among patients with unfavorable PCa treated with high-dose intensity-modulated radiation therapy (IMRT). Materials and methods: High-risk (HR) and very-high-risk (VHR) PCa patients treated with IMRT at our institution between September 2000 and December 2010 were analyzed retrospectively. Treatment consisted of high-dose IMRT (78 Gy/39 fractions) combined with 6 months of neoadjuvant-ADT (NA-ADT). S-ADT was initiated when prostate-specific antigen levels exceeded 4.0 ng/mL. Results: In total, 268 (184 HR and 84 VHR) patients were analyzed. The median follow-up period was 114.4 months. The 10-year overall survival (OS), PCa-specific survival (PCSS), biochemical failure (BF), and clinical failure (CF) rates were 82.8%, 97.1%, 27.3%, and 12.8% among the HR PCa patients and 79.4%, 87.9%, 56.2%, and 26.7% among the VHR PCa patients (p = 0.839, = 0.0377, < 0.001, and < 0.001), respectively. The 10-year cumulative incidence rates of urinary and rectal (grades 2–3) toxicities were 22.6% and 5.8%, respectively. No grade 4 or higher toxicities were observed. Conclusion: High-dose IMRT combined with short-term NA-ADT resulted in long-term disease-free status, with acceptable morbidity among approximately three-fourths of the HR PCa patients and nearly half of the VHR PCa patients. Moreover, excellent survival outcomes were achieved by the early S-ADT initiation. This approach may be a promising alternative to uniform provision of long-term ADT. [ABSTRACT FROM AUTHOR]

Hypopharyngeal invasion would be a key finding in determining the extent of the irradiation fields in patients with cervical esophageal squamous cell carcinoma (CESCC). This study aimed to investigate the clinical outcomes of chemoradiotherapy using simultaneous integrated boost intensity-modulated radiotherapy (SIB-IMRT) omitting upper cervical lymph nodal irradiation in CESCC without hypopharyngeal invasion, and the dosimetric superiority of SIB-IMRT to 3D conformal radiotherapy (3DCRT). We retrospectively identified 21 CESCC patients without hypopharyngeal invasion [clinical Stage I/II/III/IV (M1LYM); 3/6/5/7] (UICC-TNM 7th edition) who underwent chemoradiotherapy using SIB-IMRT between 2009 and 2015. SIB-IMRT delivered 60 Gy to each primary tumor and the metastatic lymph nodes, and 48 Gy to elective lymph nodal regions, including Levels III and IV of the neck, supraclavicular, and upper mediastinal lymphatic regions, in 30 fractions. The overall survival rate, locoregional control rate, and initial recurrence site were evaluated. 3DCRT plans were created to perform dosimetric comparisons with SIB-IMRT. At a median follow-up of 64.5 months, the 5-year locoregional control and overall survival rates were 66.7% and 53.4%, respectively. Disease progressed in eight patients: all were locoregional progressions and no patients developed distant progression including upper cervical lymph nodal regions as initial recurrence sites. The planning study showed SIB-IMRT improved target coverage without compromising the dose to the organs at risk, compared with 3DCRT. In conclusion, omitting the elective nodal irradiation of the upper cervical lymph nodes was probably reasonable for CESCC patients without hypopharyngeal invasion. Locoregional progression remained the major progression site in this population. [ABSTRACT FROM AUTHOR]

Background: Volumetric-modulated Dynamic WaveArc therapy (VMDWAT) is a non-coplanar continuous volumetric modulated radiation therapy (VMAT) delivery technique. Here, we monitored mechanical errors and their impact on dose distributions in VMDWAT using logfiles throughout the course of treatment.Methods: Fifteen patients were enrolled (2 skull base tumor patients and 13 prostate cancer patients). VMDWAT plans were created for the enrolled patients. The prescribed dose for the skull base tumor was set as 54 Gy at 1.8 Gy per fraction, and that for the prostate cancer was set as 72 to 78 Gy at 2 Gy per fraction. We acquired logfiles to monitor mechanical errors and their impact on dose distribution in each fraction. The root mean square error (RMSE) in the multi-leaf collimator (MLC), gantry angle, O-ring angle and monitor unit (MU) were calculated using logfiles throughout the course of VMDWAT for each patient. The dosimetric impact of mechanical errors throughout the course of VMDWAT was verified using a logfile-based dose reconstruction method. Dosimetric errors between the reconstructed plans and the original plans were assessed.Results: A total of 517 datasets, including 55 datasets for the 2 skull base tumor patients and 462 datasets for the 13 prostate cancer patients, were acquired. The RMSE values were less than 0.1 mm, 0.2°, 0.1°, and 0.4 MU for MLC position, gantry angle, O-ring angle, and MU, respectively. For the skull base tumors, the absolute mean dosimetric errors and two standard deviations throughout the course of treatment were less than 1.4% and 1.1%, respectively. For prostate cancer, these absolute values were less than 0.3% and 0.5%, respectively. The largest dosimetric error of 2.5% was observed in a skull base tumor patient. The resultant dosimetric error in the accumulated daily delivered dose distribution, in the patient with the largest error, was up to 1.6% for all dose-volumetric parameters relative to the planned dose distribution.Conclusions: MLC position, gantry rotation, O-ring rotation and MU were highly accurate and stable throughout the course of treatment. The daily dosimetric errors due to mechanical errors were small. VMDWAT provided high delivery accuracy and stability throughout the course of treatment.Trial Registration: UMIN000023870 . Registered: 1 October 2016. [ABSTRACT FROM AUTHOR]

Background: The aim of this study was to identify the long-term clinical outcome of definitive radiotherapy using three-dimensional conformal radiotherapy (3DCRT) for cervical esophageal squamous cell carcinoma (CESCC).Methods: We retrospectively reviewed the medical records of 30 patients with CESCC [clinical stage I/II/III/IV(M1LYM); 3/2/12/13] (TNM 7th edition) who underwent definitive radiotherapy using 3DCRT between 2000 and 2014 in our institution. The median prescribed dose for the gross tumor and metastatic lymph nodes was 60 Gy. Twenty-six patients underwent elective nodal irradiation for the neck node levels III, IV, and VI and for upper mediastinal lymph nodes with a median dose of 40 Gy. Twenty-six patients underwent concurrent chemotherapy. Initial disease progression sites, locoregional control (LRC) rate, overall survival (OS) rate, and toxicities were retrospectively evaluated. A univariate analysis was performed to identify prognostic factors.Results: With a median follow-up of 110 months, the 5- and 10-year LRC rates were 43.7% and 37.4%, respectively. The 5- and 10-year OS rates were 48.3% and 40.2%, respectively. Locoregional, distant and both area accounted for 83%, 6% and 11% of the initial progression sites. Unresectable status and M1LYM were significantly associated with poor LRC (p < 0.05) and OS (p < 0.05). Grade 3 acute non-hematological toxicity occurred in 13.3% of patients. During the follow-up, patients without any disease progression did not need a permanent gastrostomy tube or tracheostomy. Late toxicity events, including hypothyroidism and cardiovascular disease, were observed; 5- and 10-year cumulative incidence rates of grade 2 hypothyroidism and ≥grade 3 cardiovascular disease were 31.6% and 62.5%, and 17.5% and 21.3%, respectively.Conclusions: Definitive radiotherapy yields a cure for patients with CESCC while preserving their laryngopharyngeal function. The poor LRC rate in the advanced stage needs to be overcome for a better prognosis. As the incidence of radiation-induced hypothyroidism and cardiovascular disease was not low, long-term survivors should be followed up for these symptoms. [ABSTRACT FROM AUTHOR]

Background:The purpose was to evaluate safety and efficacy of intensity-modulated radiotherapy (IMRT) following extra-pleural pneumonectomy (EPP) for malignant pleural mesothelioma (MPM). Material and methods:Patients with MPM of clinical stage I–III, which were macroscopic completely resected with EPP were eligible for this prospective study. The ipsilateral hemithorax was irradiated with a prescribed dose of 50.4 Gy. When the high-risk surgical margins or FDG-avid regions were identified, simultaneous integrated boost (SIB) with 56.0 Gy or 61.6 Gy was applied. Results:Twenty-one patients were enrolled. SIB was applied to five patients. The planned IMRT fractions were completed in all, but four patients who suffered from severe fatigue or radiation pneumonitis. With a potential median follow-up of 6.3 years, overall survival was 37.5% at 3 years since the IMRT. The median survival time was 17.5 and 27.0 months since the IMRT and the initial treatment, respectively. Three patients have survived for more than 5 years. Distant metastasis was observed in 15 patients. Local recurrence was also observed in 2 of the 15 patients. Acute toxicities of Grade 3 or worse were observed in 15 patients, including 9 with hematological, 3 with pneumonitis and 6 with fatigue, nausea or vomiting. Five patients developed Grade 3 or worse late toxicities associated with IMRT, consisting of one with persistent Grade 4 thrombocytopenia, one with brain infarction and congestive liver dysfunction, and three with elevation of serum transaminase or biliary enzyme. No Grade 5 toxicity was observed. Patients with N2 showed significantly worse survival than those with N0–1 (18.2% vs. 60.0% at 3 years,p = .014). Conclusion:IMRT following EPP achieved excellent local control for MPM, that might lead to the long-term survival in selected patients. However, treatment burden including acute and late toxicities should be considered in this treatment approach. [ABSTRACT FROM PUBLISHER]

Purpose: The purpose of this technical note is to introduce variance component analysis to the estimation of systematic and random components in setup error of radiotherapy. Methods: Balanced data according to the one-factor random effect model were assumed. Results: Analysis-of-variance (NAOVA)-based computation was applied to estimate the values and their confidence intervals (CIs) for systematic and random errors and the population mean of setup errors. The conventional method overestimates systematic error, especially in hypofractionated settings. The CI for systematic error becomes much wider than that for random error. The ANOVA-based estimation can be extended to a multifactor model considering multiple causes of setup errors (e.g., interpatient, interfraction, and intrafraction). Conclusions: Variance component analysis may lead to novel applications to setup error analysis in radiotherapy. [ABSTRACT FROM AUTHOR]

Background: Recent studies suggest that radiation-induced injuries to the hippocampus play important roles in compromising neurocognitive functioning for patients with brain tumors and it could be important to spare the hippocampus using modern planning methods for patients with craniopharyngiomas. As bilateral hippocampus are located on the same level as the planning target volume (PTV) in patients with craniopharyngioma, it seems possible to reduce doses to hippocampus using non-coplanar beams. While the use of non-coplanar beams in volumetric-modulated arc therapy (VMAT) of malignant intracranial tumors has recently been reported, no dosimetric comparison has yet been made between VMAT using non-coplanar arcs (ncVMAT) and VMAT employing only coplanar arcs (coVMAT) among patients with craniopharyngiomas. We performed a planning study comparing dose distributions to the PTV, hippocampus, and other organs at risk (OAR) of dynamic conformal arc therapy (DCAT), coVMAT, and ncVMAT.Methods: DCAT, coVMAT, and ncVMAT plans were created for 10 patients with craniopharyngiomas. The prescription dose was 52.2 Gy in 29 fractions, and 99 % of each PTV was covered by 90 % of the prescribed dose. The maximum dose was held below 107 % of the prescribed dose. CoVMAT and ncVMAT plans were formulated to satisfy the following criteria: the doses to the hippocampus were minimized, and the doses to the OAR were similar to or lower than those of DCAT.Results: The mean equivalent doses in 2-Gy fractions to 40 % of the volumes of the bilateral hippocampus [EQD2(40%hippos)] were 15.4/10.8/6.5 Gy for DCAT/coVMAT/ncVMAT, respectively. The EQD2(40%hippos) for ncVMAT were <7.3 Gy, which is the threshold predicting cognitive impairment, as defined by Gondi et al.. The mean doses to normal brain tissue and the conformity indices were similar for the three plans, and the homogeneity indices were significantly better for coVMAT and ncVMAT compared with DCAT.Conclusions: NcVMAT is more appropriate than DCAT and coVMAT for patients with craniopharyngiomas. NcVMAT significantly reduces radiation doses to the bilateral hippocampus (to 50 % that of the DCAT) without increasing the doses to normal brain tissue and other OAR. [ABSTRACT FROM AUTHOR]