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Objective: The aim of the present study was to collect data on the characteristics, degree, and natural course of urinary complications, as well as self‐care for such complications, in patients during and after prostate intensity‐modulated radiation therapy (IMRT). Methods: Quality of life data were collected retrospectively for all eligible patients who underwent IMRT. In all eligible patients, urinary symptoms were evaluated using questionnaires and face‐to‐face interview. Participants were asked to respond to a self‐administered questionnaire concerning the core lower urinary tract symptom score during the course of IMRT and up to 12 months after the completion of IMRT. Results: In all, 29 eligible patients were included in the study. The frequency of urinary symptoms increased over of the course of IMRT, decreased at ≥3 months after completion of IMRT, and disappeared 6 months after IMRT. Responses to the questionnaire revealed a variety of approaches to self‐care and adaptations by patients to manage urinary symptoms. Conclusions: During and after IMRT for localized prostate cancer, patients often developed more frequent urination and urgency than at the start of IMRT, and recovered 3–6 months after the completion of IMRT. Based on the present study, clinicians and nurses could help convey this information to patients and thus offer better support. [ABSTRACT FROM AUTHOR]

Purpose: To optimize dose distribution for high-dose-rate brachytherapy for prostate cancer, we have developed a new algorithm named Attraction-Repulsion Model (ARM). In this study, we compared the ARM with geometric optimization (GO). Methods and Materials: The ARM was used to optimize the dose distribution by finding the best dwell time combination. ARM requires grids inside the clinical target volume (CTV) and critical organs. These grids generate attraction or repulsion based on specific dose constraints. After calculations were performed repeatedly until the attraction and repulsion forces reached equilibrium, the optimal dwell time distribution was established. We compared the ARM with GO for 10 patients using dose-volume histograms. Results: The CTV ranged from 23 to 48 cc, and the CTV V150 ranged from 52% to 79%, and 23% to 44% for GO and ARM, respectively. This indicates that the dose homogeneity indices, as well as the conformal indices, were higher for ARM than for GO. The urethra V150 was 0-99% and 0-1% for GO and ARM, respectively. Conclusion: The ARM proved to be superior to GO in minimizing the dose to normal structures and in improving dose homogeneity for the target while reducing the dose to normal tissues. [ABSTRACT FROM AUTHOR]

Purpose: This retrospective study analyzed the effect of the activity of high-dose-rate (HDR) 192Ir source on late rectal bleeding after HDR intracavitary radiotherapy (ICRT) in patients with uterine cervix cancer. Methods and Materials: One hundred thirty-two patients who underwent HDR-ICRT and external beam radiotherapy (EBRT) were analyzed. The rectal point dose in ICRT was calculated by inserting a lead wire into the rectal lumen and summed with the whole-pelvic EBRT dose. The rectal biologic effective dose (BED) was calculated. The relationship between averaged source activity or the BED and late rectal bleeding were analyzed. Results: Three-year actuarial rectal bleeding probabilities were 46% (≥100 Gy3) and 18% (≤ 100 Gy3), respectively (p < 0.005). When patients were divided into four groups according to rectal BED (≥ or ≤100 Gy3) and source activity (≥ or ≤2.4 cGy.m2.h−1), the group with both a high BED and high activity showed significantly greater probability (58% at 3 years; p < 0.005). It was noted that the probability of the group with BED of 100 Gy3 or greater was high, but that was not the case with 2.4 cGy.m2.h−1 or less. Conclusion: This is the first clinical report concerning the source activity effect of HDR 192Ir on late rectal bleeding in patients undergoing HDR-ICRT. This suggests that when source activity is higher than 2.4 cGy.m2.h−1, ICRT should be performed with more caution not to exceed 100 Gy3 in total. [Copyright &y& Elsevier]

Purpose: The aim of this study was to compare the results of high-dose rate (HDR) and medium-dose rate (MDR) intracavitary brachytherapy for carcinoma of the uterine cervix on the basis of a prospective study and to determine the dose rate conversion factor (DRCF) from low-dose rate (LDR) to MDR via HDR, because a DRCF of 0.54 from LDR to HDR has been widely accepted.Materials and Methods: Between August 1991 and July 1999, 104 patients were entered into this trial to compare results between HDR (n = 54) and MDR (n = 50). Three patients were excluded from this study, leaving 54 HDR patients and 47 MDR patients eligible. Method and dose of external beam radiotherapy were the same for both groups. For HDR intracavitary brachytherapy, point A dose was adjusted to 32 Gy/4 fractions for stages I and II, to 30 Gy/4 fractions for stage III, and to 22.5 Gy/3 fractions for stage IV. The corresponding values for MDR were 35.6 Gy/4 fractions, 34 Gy/4 fractions, and 25.5 Gy/3 fractions. The average dose rate at point A was 30 Gy/hour (9.0–65.2) for HDR and 1.7 Gy/hour (1.3–2.2) for MDR. We assumed a DRCF of 0.9 from MDR to HDR.Results: The 3-year cause-specific survival rates for HDR were 85%, 83%, 75%, and 0% for stages I, II, III, and IV, respectively. The corresponding figures for MDR were 100%, 82%, 58%, and 40%. Six of the HDR patients (11%) and 2 of the MDR patients (4%) developed Kottmeier''s grade 2 or 3 late complications. A DRCF of 0.6 from LDR to MDR could be derived from a DRCF of 0.9 from MDR to HDR and one of 0.54 from LDR to HDR.Conclusions: There were no statistically significant differences in cause-specific survival and incidence of late complications between HDR and MDR. A DRCF of 0.6 from LDR to MDR could be determined. However, because the results of this trial were preliminary, a further study is needed. [Copyright &y& Elsevier]

Purpose: We developed a software program for swiftly calculating dose distributions for carbon ion beams. This study aims to evaluate the accuracy of dose calculations using this software and assess the robustness of dose distribution in treating prostate cancer., Methods: At the Osaka Heavy Ion Therapy Center, markers are inserted into the prostate gland and used for position verification. To account for geometric changes along the beam path due to marker translation, a beam-specific planning target volume (bsPTV) is set for each beam. To validate the accuracy of the dose calculations using the developed software, dose distributions for prostate and sarcoma cases were calculated and compared with the treatment planning system. To assess the robustness of the dose distribution, position verification data from 346 cases were utilized to reproduce dose distributions for three matching methods: bone matching, widely adopted in most particle therapy centers; marker translation, which involves direct translation to markers without bone matching; and marker translation after bone matching. The coverage of the target (D 99 of clinical target volume (CTV)) was assessed to evaluate the robustness of the dose distribution. Additionally, statistical analyses were conducted for the dose distributions of each matching method., Results: The dose calculation for a single condition can be completed very quickly. Statistical analysis revealed significant differences among dose distributions considering the three matching methods. When irradiation was performed with bone matching only, the D 99 was reduced by more than 10% in approximately 7.5% of cases, making it as the poorest among the three matching methods. However, there was no significant reduction in target coverage with the other two methods., Conclusion: We have demonstrated the accuracy of the developed software for rapidly calculating dose distributions for carbon ion beams and confirmed the robustness of the dose distributions based on the bsPTV., (© 2024 The Author(s). Journal of Applied Clinical Medical Physics published by Wiley Periodicals, LLC on behalf of The American Association of Physicists in Medicine.)

Introduction: The study aimed to evaluate the efficacy and safety of dose-escalated stereotactic body radiotherapy (SBRT) for primary lung cancer., Methods: Patients with peripherally located T1-2N0M0 primary lung cancer who underwent SBRT from April 2013 to December 2019 were included. Group A received 60 Gy in five fractions with CyberKnife prescribed at 99% gross tumor volume. Group B received 48 Gy in four fractions by a gantry-mounted linear accelerator, with isocenter prescription. Cumulative incidence of local failure (LF), progression free survival (PFS), overall survival (OS), and toxicity were retrospectively compared., Results: Groups A and B comprised 39 and 36 patients, respectively. Group A had more patients without histological confirmation (p < .001) and showed lower V20 of bilateral lungs (p = .025). The median follow-up duration of Group A and B was 22.0 and 21.5 months, respectively, and the 2-year cumulative incidence of LF, PFS, and OS were .0% versus 11.6% (p = .065), 66.2% versus 62.7% (p = .694), 84.1% versus 81.1% (p = .827), respectively. There was no difference in Grade ≥ 2 toxicity rate between Groups A and B (7.7% vs. 11.1%; p = .704)., Conclusion: Dose-escalated SBRT using CyberKnife showed reduced lung dose and potential benefits for improved local control with comparable toxicity., (© 2022 John Wiley & Sons Australia, Ltd.)

Background/aim: Stereotactic body radiotherapy for prostate cancer using CyberKnife with circular cone requires a long treatment time. Raster scanning intensity modulated radiotherapy (RS-IMRT) has a potential of improving treatment efficacy, introducing shorter treatment time, better target dose uniformity, and lower organ at risk (OAR) dose. The purpose of the study was to develop a fluence optimization system for RS-IMRT., Patients and Methods: RS-IMRT plans were created for five prostate cancer patients treated with the Novalis system and parameters were compared to the Novalis treatment plans. From 80 nodes available for the CyberKnife, twelve nodes were arbitrarily selected. On the beam's eye view of each beam, a 100×100 matrix of optimization points was created at the target center plane. The beam fluence map was optimized using the attraction-repulsion model (ARM). The beam fluence maps were converted to the scanning sequence using the ARM and a final dose calculation was performed., Results: For planning target volume (PTV), RS-IMRT plans showed higher dose covering 2% of the volume (D 2% ) and lower D 98% compared to the Novalis plans. However, the homogeneity was within our Institutional clinical protocol. The RS-IMRT plans showed significantly lower OAR dose parameters including bladder volume receiving 100% of prescribed dose (V 100% ) and dose delivered to 5 cm 3 of rectum (D 5 cc )., Conclusion: We developed a fluence optimization system for RS-IMRT that performs the entire RS-IMRT treatment planning process, including scanning sequence optimization and final dose calculation. The RS-IMRT was capable of generating clinically acceptable plans., (Copyright © 2023 International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.)

Background/aim: Lung and liver tumor dose coverage was evaluated for the CyberKnife synchrony respiratory tracking system (SRTS) with consideration of the motion tracking accuracy measured for motion patterns of individual patients., Patients and Methods: Seven treatment plans of six cases treated with the SRTS were evaluated. The motion phantom was moved with the motion data derived from the treatment log files. A laser emitted from the linac head to the moving phantom block was recorded with a webcam, and the tracking accuracy was evaluated. The dose volume histogram (DVH) of planning target volume (PTV) and gross tumor volume (GTV) were calculated by a pencil beam algorithm with shifting the beams with Gaussian random numbers mimicking the measured tracking errors., Results: The tracking errors measured with the motion phantom in the lateral direction were within ±2 mm for 90% of beam-on time. The tracking errors in the longitudinal direction were within ±3.0 mm and ±1.1 mm for 90% and 50% of beam-on time, respectively. Although one case showed a decrease in the dose covering 95% of PTV (D 95% ) by 1.8%, the change in the dose covering 99% of GTV (D 99% ) was within 1%., Conclusion: This study evaluated the motion tracking errors of the SRTS by a motion phantom moved with the patients' respiration signal, and the impact of the tracking errors on the target coverage was calculated. Even for respiratory patterns with large maximum tracking errors, sufficient GTV coverage is achievable if the beam is accurately delivered for high percentage of beam-on time., (Copyright © 2023 International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.)

Background/aim: We evaluated the effectiveness and safety of stereotactic ablative radiotherapy (SABR) delivered using Cyberknife in patients with stage I non-small-cell lung cancer., Patients and Methods: The clinical results of 153 patients with 161 lung cancers treated with CyberKnife between May 2014 and August 2020 at the Osaka University Hospital were retrospectively analyzed. The median age was 80 years (range=48-99 years). Nine patients (5.6%) had interstitial pneumonia. The median radiation dose was 52 Gy (range=40-70 Gy) in 4-10 fractions, and the median follow-up extended to 21.4 months (range=0-68.9 months)., Results: The 2-year local control, progression-free, and overall survival rates were 91.9%, 61.7%, and 84.8%, respectively. Toxicities of grade ≥3 were observed in 13 (8.1%) patients; one patient with interstitial pneumonia developed grade 5 radiation pneumonitis and one patient developed grade 5 bronchopulmonary hemorrhage., Conclusion: In patients with stage I non-small-cell lung cancer, SABR using Cyberknife was effective with acceptable toxicity., (Copyright © 2022 International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.)

Background: This study aimed to assess the need to consider microscopic invasion in terms of treatment planning in stereotactic body radiation therapy (SBRT) for hepatocellular carcinoma and elucidate the appropriate clinical target volume (CTV) margin., Patients and Methods: A total of 121 patients (with 146 liver tumors) who underwent SBRT between July 2007 and August 2016 were analyzed, regarding overall survival and local control (LC)., Results: The 2- and 5-year LC rates were 91.5% and 89.8%, respectively. Planning target volume (PTV) margin <8 mm was associated with poor LC. Of the 77 patients with PTV margin of <8 mm, age <75 years was associated with poor LC, while alpha-fetoprotein (AFP) ≤20 ng/ml was associated with good LC., Conclusion: In patients with high AFP levels, there is a possibility of microscopic invasion around the tumor, suggesting that LC may be improved by adding an additional clinical target volume margin to the gross tumor volume., (Copyright© 2018, International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.)

Surgical resection is a well-established treatment option for sarcoma. However, anatomical barriers often hamper radical surgical procedures. The treatment of unresectable sarcoma, including local or distant failures following initial treatment, is challenging. The aim of the present study was to analyze the outcome of radiotherapy (RT) for refractory sarcoma, including unresectable, metastatic and recurrent disease, following radical treatment. We retrospectively reviewed a total of 67 tumors in 28 patients who were treated with RT between 2007 and 2014. Clinical target volume (CTV) was generally not defined in a preventive manner; therefore, in the majority of the cases, CTV equaled the gross tumor volume. The total delivered dose, number of fractions and biological equivalent dose were 52 (range, 40-69), 10 (range, 4-24) and 92.2 (range, 56-119.6) Gy, respectively. Only 1 patient developed local failure, with a median follow-up of 11 months (range, 1-59 months). Therefore, the 12-month progression-free survival rate for 67 sites was 96.8%. The overall survival rates at 12 and 36 months were 75.8 and 30.2%, respectively. A total of 2 patients developed grade >2 toxicities, including grade 3 mucositis and grade 4 pericardial effusion. Our results demonstrated that radical RT using modern techniques is highly feasible, achieves excellent local control, and may be an effective treatment option for refractory sarcoma.