Comparison of beam segment versus full plan re-optimization in daily magnetic resonance imaging-guided online-adaptive radiotherapy.
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ABSTRACT:
SUBMITTER: van Timmeren JE
PROVIDER: S-EPMC8058019 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:BackgroundTreatment adaptation based on tumour biomarker response during radiotherapy of prostate cancer, could be used for both escalation and de-escalation of radiation doses and volumes. To execute an adaptation involving extension of treatment volumes during radiation can however be restricted by the doses already delivered. The aim of this work was to develop a treatment planning method that addresses this challenge.Material and methodsA volumetric-modulated-arc-therapy (VMAT) planning method with sequential plan-on-plan optimization was developed for a prospective phase II trial including 100 patients on salvage radiotherapy (SRT) for prostate cancer recurrence. A treatment adaptation was performed after five weeks of SRT based on prostate-specific antigen response during this phase of the treatment. This involved extension of treatment volumes for non-responders (n = 64) to include pelvic lymph nodes and boost to 68Gallium-Prostate-Specific-Membrane-Antigen-Positron-Emission-Tomography positive lesions. This method was evolved by introducing an EQD2 (equivalent dose in 2.0 Gy fractions) correction of the base plan for improved dose coverage.ResultsAll dose-volume criteria for target coverage were met for the non-responders when based on physical dose. An EQD2 correction of the base plan for non-responders, implemented for the final 29 patients, led to a statistically significant improvement in dose coverage as compared to the 35 patients treated without EQD2 correction.ConclusionsThis is to our knowledge the only study presented on biomarker-guided sequential VMAT radiotherapy using a plan-on-plan technique in the pelvis. By using a biologically adapted technique an improved target coverage was achieved without compromising doses to organs at risk.
| S-EPMC8254191 | biostudies-literature
Project description:Background and purposeIn daily adaptive magnetic resonance (MR)-guided radiotherapy, plans are adapted based on the patient's daily anatomy. During this adaptation phase, prostate intrafraction motion (IM) can occur. The aim of this study was to investigate the efficacy of always applying a subsequent virtual couch shift (VCS) to counter IM that occurred during the daily contour and plan adaption (CPa) procedure.Material and methodsOne hundred fifty patients with low and intermediate risk prostate cancer were treated with 5x7.25 Gy fractions on a 1.5 T MR-Linac. In each fraction, contour adaptation and dose re-optimization was performed using the session's first MR-scan. IM that occurred here was countered using two methods. One patient group had selective VCS (sVCS) applied if the CTV reached outside the PTV on a second MR acquired during plan optimization. The other group had always VCS (aVCS) applied for any prostate shift greater than 1 mm. Remaining IM during beam delivery was determined using 3D cine-MR.ResultsPercentage of fractions where a VCS was applied was 28% (sVCS) vs 78% (aVCS). Always applying VCS significantly reduced influences of systematic prostate IM. Population random and systematic median values in all translations directions were lower for the aVCS than sVCS group, but not for the population random cranial-caudal direction.ConclusionApplying VCS after daily CPa reduced impact of systematic prostate drift in especially the posterior and caudal translation direction. However, due to the continuous and stochastical nature of prostate IM, margin reduction below 4 mm requires fast intrafraction plan adaption methods.
| S-EPMC8327343 | biostudies-literature
Project description:BACKGROUND:Online adaptive radiotherapy is intended to prevent plan degradation caused by inter-fractional tumor volume and shape changes, but time limitations make online re-planning challenging. The aim of this study was to compare the quality of online-adapted plans to their respective reference treatment plans. METHODS:Fifty-two patients treated on a ViewRay MRIdian Linac were included in this retrospective study. In total 238 online-adapted plans were analyzed, which were optimized with either changing of the segment weights (n =?85) or full re-optimization (n =?153). Five different treatment sites were evaluated: prostate, abdomen, liver, lung and pelvis. Dosimetric parameters of gross tumor volume (GTV), planning target volume (PTV), 2?cm ring around the PTV and organs at risk (OARs) were considered. The Wilcoxon signed-rank test was used to assess differences between online-adapted and reference treatment plans, p <?0.05 was considered significant. RESULTS:The average duration of the online adaptation, consisting of contour editing, plan optimization and quality assurance (QA), was 24?± 6?min. The GTV was slightly larger (average?±?SD: 1.9%?±?9.0%) in the adapted plans than in the reference plans (p <?0.001). GTV-D95% exhibited no significant changes when considering all plans, but GTV-D2% increased by 0.40%?±?1.5% on average (p <?0.001). There was a very small yet significant decrease in GTV-coverage for the abdomen plans. The ring Dmean increased on average by 1.0%?±?3.6% considering all plans (p <?0.001). There was a significant reduction of the dose to the rectum of 4.7%?±?16% on average (p <?0.001) for prostate plans. CONCLUSIONS:Dosimetric quality of online-adapted plans was comparable to reference treatment plans and OAR dose was either comparable or decreased, depending on treatment site. However, dose spillage was slightly increased.
| S-EPMC7441614 | biostudies-literature
Project description:BACKGROUND AND PURPOSE:Incidental irradiation of normal brain tissue during radiotherapy is linked to cognitive decline, and may be mediated by damage to healthy cortex. Non-coplanar techniques may be used for cortical sparing. We compared normal brain sparing and probability of cortical atrophy using 4? radiation therapy planning vs. standard fixed gantry intensity-modulated radiotherapy (IMRT). MATERIAL AND METHODS:Plans from previously irradiated brain tumor patients ("original IMRT", n?=?13) were re-planned to spare cortex using both 4? optimization ("4?") and IMRT optimization ("optimized IMRT"). Homogeneity index (HI), gradient measure, doses to cortex and white matter (excluding tumor), brainstem, optics, and hippocampus were compared with matching PTV coverage. Probability of three grades of post-treatment cortical atrophy was modeled based on previously established dose response curves. RESULTS:With matching PTV coverage, 4? significantly improved HI by 27% (p?=?0.005) and gradient measure by 8% (p?=?0.001) compared with optimized IMRT. 4? optimization reduced mean and equivalent uniform doses (EUD) to all standard OARs, with 14-15% reduction in hippocampal EUD (p???0.003) compared with the other two plans. 4? significantly reduced dose to fractional cortical volumes (V50, V40 and V30) compared with the original IMRT plans, and reduced cortical V30 by 7% (p?=?0.008) compared with optimized IMRT. White matter EUD, mean dose, and fractional volumes V50, V40 and V30 were also significantly lower with 4? (p???0.001). With 4?, probability of grade 1, 2 and 3 cortical atrophy decreased by 12%, 21% and 26% compared with original IMRT and by 8%, 14% and 3% compared with optimized IMRT, respectively (p???0.001). CONCLUSIONS:4? radiotherapy significantly improved cortical sparing and reduced doses to standard brain OARs, white matter, and the hippocampus. This was achieved with superior PTV dose homogeneity. Such sparing could reduce the probability of cortical atrophy that may lead to cognitive decline.
| S-EPMC6084493 | biostudies-literature
Project description:Background and purposeStudies have demonstrated the potential of online adaptive radiotherapy (oART). However, routine use has been limited due to resource demanding solutions. This study reports on experiences with oART in the pelvic region using a novel cone-beam computed tomography (CBCT)-based, artificial intelligence (AI)-driven solution.Material and methodsAutomated pre-treatment planning for thirty-nine pelvic cases (bladder, rectum, anal, and prostate), and one hundred oART simulations were conducted in a pre-clinical release of Ethos (Varian Medical Systems, Palo Alto, CA). Plan quality, AI-segmentation accuracy, oART feasibility and an integrated calculation-based quality assurance solution were evaluated. Experiences from the first five clinical oART patients (three bladder, one rectum and one sarcoma) are reported.ResultsAuto-generated pre-treatment plans demonstrated similar planning target volume (PTV) coverage and organs at risk doses, compared to institution reference. More than 75% of AI-segmentations during simulated oART required none or minor editing and the adapted plan was superior in 88% of cases. Limitations in AI-segmentation correlated to cases where AI model training was lacking. The five first treated patients complied well with the median adaptive procedure duration of 17.6 min (from CBCT acceptance to treatment delivery start). The treated bladder patients demonstrated a 42% median primary PTV reduction, indicating a 24%-30% reduction in V45Gy to the bowel cavity, compared to non-ART.ConclusionsA novel commercial oART solution was demonstrated feasible for various pelvic sites. Clinically acceptable AI-segmentation and auto-planning enabled adaptation within reasonable timeslots. Possibilities for reduced PTVs observed for bladder cancer indicated potential for toxicity reductions.
| S-EPMC8057957 | biostudies-literature
Project description:ObjectiveIntensity modulated radiation therapy (IMRT) using a volumetric-modulated arc therapy technique may offer dosimetric and clinical benefits compared to the historical standard of care 3D-conformal radiotherapy (3D-CRT) in definitive treatment of bladder cancer. We hypothesized that IMRT with CBCT would reduce dose to the rectum, bowel, and bladder compared to 3D-CRT.MethodsWe reviewed nineteen patients treated with maximal transurethral resection of bladder tumor followed by concurrent chemotherapy with IMRT. All patients received 45 Gy to the entire empty bladder followed by 19.8 Gy tumor boost treated with full bladder. 3D-CRT treatment plans were created for the same prescription. Paired t-test or Wilcoxon matched-pairs signed rank test analyzed dosimetry and bladder volumes.ResultsThe rectum and bowel V40, V45, V50, V55, and V60 were reduced by over 50% in the IMRT plans compared to 3D-CRT (p<0.0001). IMRT also reduced volume of bladder irradiated compared to 3D-CRT (p<0.01). After CBCT, patients were likely to undergo clinically significant shifts ? 0.5 cm before boost delivery (p=0.001). Bladder volumes were significantly lower during boost treatments compared to pre-treatment simulation (p=0.002). There were 4 (21%) grade 3 genitourinary toxicities and 1 (5%) grade 3 gastrointestinal toxicity.ConclusionIMRT is superior to 3D-CRT for bladder cancer and spares dose to bowel, rectum, and bladder with improved acute toxicity compared to published clinical literature. For boost treatment, daily full bladder volume and positioning are not always reproducible, supporting the need for CBCT for optimal localization of the primary bladder tumor.
| S-EPMC7747671 | biostudies-literature
Project description:Purpose Stereotactic magnetic resonance (MR)–guided adaptive radiation therapy (SMART) for prostate cancer allows for MR-based contouring, real-time MR motion management, and daily plan adaptation. The clinical and dosimetric benefits associated with prostate SMART remain largely unknown. Methods and Materials A phase 1 trial of prostate SMART was conducted with primary endpoints of safety and feasibility. An additional cohort of patients similarly treated with prostate SMART were included in the analysis. SMART was delivered to 36.25 Gy in 5 fractions to the prostate ± seminal vesicles using the MRIdian linear accelerator system (ViewRay, Inc). Rates of urinary and gastrointestinal toxic effects and patient-reported outcome measures were assessed. Dosimetric analyses were conducted to evaluate the specific benefits of daily plan adaptation. Results The cohort included 22 patients (n = 10 phase 1, n = 12 supplemental) treated in 110 fractions. Median follow-up was 7.9 months. Acute grade 2 urinary and gastrointestinal toxic effects were observed in 22.7% and 4.5%, respectively, and 4.5% and 0%, respectively, at last follow-up. No grade 3+ events were observed. Expanded Prostate Cancer Index-26 urinary obstructive scores decreased during SMART (mean, 9.3 points; P = .03) and returned to baseline by 3 months. No other significant changes in patient-reported outcome measures were observed. One-hundred percent of fractions required plan adaptation owing to exceeding organ-at-risk metrics (68%) or suboptimal target coverage (33%) resulting from anatomic changes. Minimum acceptable planning target volume, rectal, bladder, and urethra/bladder neck metrics were violated in 24%, 20%, 24%, and 33% of predicted plans, respectively; 0% of reoptimized plans violated metrics. Underlying causes for deficient dosimetry before reoptimization included changes in bladder filling, seminal vesicle position, prostate volume (median 4.7% increase by fraction 3; range, 0%-56%), and hotspots shifting into urethra/bladder neck. Conclusions Prostate SMART results in low risk of acute toxic effects with improvements in target and organ-at-risk dosimetry. The clinical benefits resulting from daily plan adaptation, including urethra/bladder neck protection, warrant further investigation.
| S-EPMC9280019 | biostudies-literature
Project description:BACKGROUND:To compare online adaptive radiation therapy (ART) to a clinically implemented plan selection strategy (PS) with respect to dose to the organs at risk (OAR) for rectal cancer. METHODS:The first 20 patients treated with PS between May-September 2016 were included. This resulted in 10 short (SCRT) and 10 long (LCRT) course radiotherapy treatment schedules with a total of 300 Conebeam CT scans (CBCT). New dual arc VMAT plans were generated using auto-planning for both the online ART and PS strategy. For each fraction bowel bag, bladder and mesorectum were delineated on daily Conebeam CTs. The dose distribution planned was used to calculate daily DVHs. Coverage of the CTV was calculated, as defined by the dose received by 99% of the CTV volume (D99%). The volume of normal tissue irradiated with 95% of the prescribed fraction dose was calculated by calculating the volume receiving 95% of the prescribed fraction or more dose minus the volume of the CTV. For each fraction the difference between the plan selection and online adaptive strategy of each DVH parameter was calculated, as well as the average difference per patient. RESULTS:Target coverage remained the same for online ART. The median volume of the normal tissue irradiated with 95% of the prescribed dose dropped from 642?cm3 (PS) to 237?cm3 (online-ART)(p <?0.001). Online ART reduced dose to the OARs for all tested dose levels for SCRT and LCRT (p <?0.001). For V15Gy of the bowel bag the median difference over all fractions of all patients was -?126?cm3 in LCRT, while the average difference per patient ranged from -?206?cm3 to -?40?cm3. For SCRT the median difference was -?62?cm3, while the range of the average difference per patient was -?105?cm3 to -?51?cm3. For V15Gy of the bladder the median difference over all fractions of all patients was 26% in LCRT, while the average difference per patient ranged from -?34 to 12%. For SCRT the median difference of V95% was -?8%, while the range of the average difference per patient was -?29 to 0%. CONCLUSIONS:Online ART for rectal cancer reduces dose the OARs significantly compared to a clinically implemented plan selection strategy, without compromising target coverage. TRIAL REGISTRATION:Medical Research Involving Human Subjects Act (WMO) does not apply to this study and was retrospectively approved by the Medical Ethics review Committee of the Academic Medical Center (W19_357 # 19.420; Amsterdam University Medical Centers, Location Academic Medical Center, Amsterdam, The Netherlands).
| S-EPMC7371470 | biostudies-literature
Project description:Magnetic Resonance-guided Radiotherapy (MRgRT) allows direct monitoring of treated volumes. The aim of this study was to investigate the feasibility of a new gating strategy consisting in using an isodose as boundary. Forty-four patients treated for thoracic and abdominal lesions using MRgRT were enrolled. The accuracy of the new strategy was compared to the conventional one in terms of area improvement available for gating without compromising target coverage. A mean increase of 24% for lung, 15% for liver and 11% for pancreas was observed, demonstrating how the new method can be useful in challenging situations with low dose conformality.
| S-EPMC8254198 | biostudies-literature
Project description:Introduction:To evaluate the clinical response rate after a postoperative 18F-FDG PET/CT guided external beam radiotherapy (EBRT) in Iodine-refractory differentiated thyroid cancer. Material and Methods:Patients with thyroid cancer locally recurrent after total thyroidectomy plus metabolic radiotherapy and treated with radical EBRT were included. Inclusion criteria were detectable thyroglobulin (Tg), negative postmetabolic radiotherapy whole body scintigraphy, and no surgical indications. The pretreatment 18F-FDG PET/CT resulted positive in all cases (loggia, lymph nodes, and lung). EBRT was delivered with IMRT-SIB technique. A 18F-FDG PET/CT revaluation and Tg dosage were performed 3 months after the treatment. Results:Sixteen consecutive patients were included in this analysis (median follow-up: 6-44 months). Post-EBRT 18F-FDG PET/CT showed CR in 43.7%, PR in 31.2%, SD in 25.0% patients, and PD due to lung metastases in 12.5%. Overall response rate was 75.0% (CI 95%: 41.4-93.3%). Tg levels decreased in 75.0% with a median ? of 68.0%. Two-year PFS and OS rates were 80.0% and 93.0%, respectively. Acute G3 toxicity occurred in 18.7% and late G2 toxicity in 12.5%. Conclusions:18F-FDG PET/CT was useful in target definition for radiotherapy planning, identifying positive areas not detected with 131I scintigraphy. IMRT based EBRT was feasible and our results encourage future prospective studies. This clinical trial is registered with ID: NCT03191643.
| S-EPMC5671737 | biostudies-literature