Search

Historically, total body irradiation (TBI) has been delivered using static, parallel opposed photon beams (2D-TBI). Recently, centers have increasingly used intensity-modulated radiation therapy (IMRT) techniques for TBI. Relative to 2D-TBI, IMRT can reduce doses to critical organs (i.e., lungs and kidneys) while delivering myeloablative doses to the rest of the body, so it may decrease the risk of toxicity while maintaining oncologic outcomes. Despite these potential benefits, delivering TBI using IMRT introduces new challenges in treatment planning and delivery. We describe the extensive experience with IMRT-based TBI at Stanford University and City of Hope Cancer Center. These groups, and others, have reported favorable clinical outcomes and have developed methods to optimize treatment planning and delivery. A critical next step is to evaluate the broader adoption of this approach. Therefore, IMRT-based TBI will be incorporated into a prospective, multi-institutional Children's Oncology Group study with careful procedures and safeguards in place., (© 2024 Wiley Periodicals LLC.)

Purpose/objectives: To evaluate dosimetric differences between auto-planned volumetric modulated arc therapy (VMAT) total body irradiation (TBI) technique and two-dimensional radiotherapy using anterior-posterial/posterio-anterial beams (2D AP/PA) TBI technique., Methods: Ten pediatric patients treated with VMAT-TBI on Varian c-arm linac were included in this study. VMAT-TBI plans were generated using our in-house developed and publicly shared auto-planning scripts. For each VMAT-TBI plan, a 2D AP/PA plan was created replicating the institution's clinical setup with the patient positioned at extended source to skin distance (SSD) with a compensator to account for differences in patient thickness, 50% transmission daily lung blocks, and electron chest wall boosts prescribed to 50% of the photon prescription. Clinically relevant metrics were analyzed and compared between the VMAT and 2D plans., Results: All VMAT-TBI plans achieved planned target volume (PTV) D90% ≥ 100% of prescription. VMAT-TBI PTV D90% significantly increased (7.1% ± 2.9%, p < .001) compared to the 2D technique, whereas no differences were observed in global D max (p < .2) and PTV V110% (p < .4). Compared to the 2D plans, significant decreases in the D mean to the lungs (-25.6% ± 11.5%, p < .001) and lungs-1 cm (-34.1% ± 10.1%, p < .001) were observed with the VMAT plans. The VMAT technique also enabled decrease of dose to other organs: kidneys D mean (-32.5% ± 5.0%, p < .001) and lenses D max (-5.3% ± 8.1%, p = .03); and in addition, for 2 Gy prescription: testes/ovaries D mean (-41.5% ± 11.5%, p < .001), brain D mean (-22.6% ± 5.4%, p = .002), and thyroid D mean (-18.2% ± 16.0%, p = .03)., Conclusions: Superior lung sparing with improved target coverage and similar global D max were observed with the VMAT plans as compared to 2D plans. In addition, VMAT-TBI plans provided greater dose reductions in gonads, kidneys, brain, thyroid, and lenses., (© 2023 Wiley Periodicals LLC.)

Purpose: The RefleXion X1 is a novel radiotherapy machine designed for image-guided radiotherapy (IGRT) and biology-guided radiotherapy (BgRT). Its treatment planning system (TPS) generates IMRT and SBRT plans for a 6MV-FFF beam delivered axially via 50 firing positions with the couch advancing every 2.1 mm. The purpose of this work is to report the TPS commissioning results for the first clinical installation of RefleXion™ X1., Methods: CT images of multiple phantoms were imported into the RefleXion TPS to evaluate the accuracy of data transfer, anatomical modeling, plan evaluation, and dose calculation. Comparisons were made between the X1, Eclipse™, and MIM™. Dosimetric parameters for open static fields were evaluated in water and heterogeneous slab phantoms. Representative clinical IMRT and SBRT cases were planned and verified with ion chamber, film, and ArcCHECK @ measurements. The agreement between TPS and measurements for various clinical plans was evaluated using Gamma analysis with a criterion of 3%/2 mm for ArcCHECK @ and film. End-to-end (E2E) testing was performed using anthropomorphic head and lung phantoms., Results: The average difference between the TPS-reported and known HU values was -1.4 ± 6.0 HU. For static fields, the agreements between the TPS-calculated and measured PDD 10 , crossline profiles, and inline profiles (FWHM) were within 1.5%, 1.3%, and 0.5 mm, respectively. Measured output factors agreed with the TPS within 1.3%. Measured and calculated dose for static fields in heterogeneous phantoms agreed within 2.5%. The ArcCHECK @ mean absolute Gamma passing rate was 96.4% ± 3.4% for TG 119 and TG 244 plans and 97.8% ± 3.6% for the 21 clinical plans. E2E film analysis showed 0.8 mm total targeting error for isocentric and 1.1 mm for off-axis treatments., Conclusions: The TPS commissioning results of the RefleXion X1 TPS were within the tolerances specified by AAPM TG 53, MPPG 5.a, TG 119, and TG 148. A subset of the commissioning tests has been identified as baseline data for an ongoing QA program., (© 2022 The Authors. Journal of Applied Clinical Medical Physics published by Wiley Periodicals, LLC on behalf of The American Association of Physicists in Medicine.)

Introduction: Total body irradiation (TBI) is an important component of many conditioning regimens for hematopoietic stem cell transplantation (HSCT), most commonly used in pediatric and adolescent/young adult (AYA) patients. We aimed to evaluate outcomes and toxicities among pediatric and AYA patients treated with TBI utilizing volumetric modulated arc therapy total body irradiation (VMAT-TBI)., Methods: We reviewed pediatric and AYA patients treated with VMAT-TBI at our institution from 2019 to 2021. Data on patient and disease characteristics, treatment details, outcomes and toxicities were collected. Overall survival (OS) and relapse-free survival (RFS) were analyzed using the Kaplan-Meier method., Results: Among 38 patients, 16 (42.1%) were treated with myeloablative regimens and 22 (57.9%) with nonmyeloablative regimens. Median age was 7.2 years (range: 1-27) and median follow-up was 8.7 months (range: 1-21). Lungs D mean was 7.3 ± 0.3 Gy for myeloablative regimens (range: 6.8-7.8). Kidneys were spared to average mean dose of 71.4 ± 4.8% of prescription dose. Gonadal sparing was achieved for patients treated for nonmalignant diseases to D mean of 0.7 ± 0.1 Gy. No patient experienced primary graft failure; one (2.6%) experienced secondary graft failure. The most common grade 1-2 acute toxicities were nausea (68.4%) and fatigue (55.3%). Mucositis was the most common grade 3-4 acute toxicity, affecting 39.5% of patients. There were no cases of pneumonitis or nephrotoxicity attributable to TBI., Conclusion: VMAT-TBI offers increased ability to spare organs at risk in pediatric and AYA patients undergoing HSCT, with a favorable acute/subacute toxicity profile and excellent disease control., (© 2022 Wiley Periodicals LLC.)

Purpose: In this article, we describe the technical aspects of the Stanford volumetric modulated arc therapy (VMAT) total body irradiation (TBI) technique, compare it with other VMAT-TBI techniques, and share our initial experience., Methods and Materials: From September 2019 to August 2021, 35 patients were treated with VMAT-TBI at our institution. Treatment planning was performed using in-house developed automated planning scripts. Organ sparing depended on the regimen: myeloablative (lungs, kidneys, and lenses) and nonmyeloablative with benign disease (lungs, kidneys, lenses, gonads, brain, and thyroid). Quality assurance was performed using electronic portal imaging device portal dosimetry and Mobius3D. Robustness was evaluated for the first 10 patients by performing local and global isocenter shifts of 5 mm. Treatment was delivered using image-guided radiation therapy for every isocenter and every fraction. In vivo measurements were performed on the match line between the VMAT and anterior-posterior/posterior-anterior fields and on the testes for the first fraction., Results: The lungs, lungs - 1 cm, and kidneys D mean were consistently spared to 57.6% ± 4.4%, 40.7% ± 5.5%, and 70.0% ± 9.9% of the prescription dose, respectively. Gonadal sparing (D mean  = 0.69 ± 0.13 Gy) was performed for all patients with benign disease. The average planning target volume (PTV) maximum dose to 1 cubic centimeter (D 1cc ) was 120.7% ± 6.4% for all patients. The average Gamma passing rate for the VMAT plans was 98.1% ± 1.6% (criterion of 3%/2 mm). Minimal differences were observed between Mobius3D- and Eclipse AAA-calculated PTV D mean (0.0% ± 0.3%) and lungs D mean (-2.5% ± 1.2%). Robustness evaluation showed that the PTV D max and lungs D mean were insensitive to small positioning deviations between the VMAT isocenters (1.1% ± 2.4% and 1.2% ± 1.0%, respectively). The average match-line dose measurement indicated patient setup was reproducible (96.1% ± 4.5% relative to prescription dose). Treatment time, including patient setup and beam-on, was 47.5 ± 9.5 min., Conclusions: The Stanford VMAT-TBI technique, from simulation to treatment delivery, was presented and compared with other VMAT-TBI techniques. Together with publicly shared autoplanning scripts, our technique may provide the gateway for wider adaptation of this technology and the possibility of multi-institutional studies in the cooperative group setting., (Copyright © 2022 American Society for Radiation Oncology. Published by Elsevier Inc. All rights reserved.)

Purpose: The first clinical biology-guided radiation therapy (BgRT) system-RefleXion TM X1-was installed and commissioned for clinical use at our institution. This study aimed at evaluating the treatment plan quality and delivery efficiency for IMRT/SBRT cases without PET guidance. Methods: A total of 42 patient plans across 6 cancer sites (conventionally fractionated lung, head, and neck, anus, prostate, brain, and lung SBRT) planned with the Eclipse TM treatment planning system (TPS) and treated with either a TrueBeam ® or Trilogy ® were selected for this retrospective study. For each Eclipse VMAT plan, 2 corresponding plans were generated on the X1 TPS with 10 mm jaws (X1-10mm) and 20 mm jaws (X1-20mm) using our institutional planning constraints. All clinically relevant metrics in this study, including PTV D95%, PTV D2%, Conformity Index (CI), R50, organs-at-risk (OAR) constraints, and beam-on time were analyzed and compared between 126 VMAT and RefleXion plans using paired t -tests. Results: All but 3 planning metrics were either equivalent or superior for the X1-10mm plans as compared to the Eclipse VMAT plans across all planning sites investigated. The Eclipse VMAT and X1-10mm plans generally achieved superior plan quality and sharper dose fall-off superior/inferior to targets as compared to the X1-20mm plans, however, the X1-20mm plans were still considered acceptable for treatment. On average, the required beam-on time increased by a factor of 1.6 across all sites for X1-10mm compared to X1-20mm plans. Conclusions: Clinically acceptable IMRT/SBRT treatment plans were generated with the X1 TPS for both the 10 mm and 20 mm jaw settings.

Purpose: Our purpose was to automate the treatment planning process for total body irradiation (TBI) with volumetric modulated arc therapy (VMAT)., Methods and Materials: Two scripts were developed to facilitate autoplanning: the binary plug-in script automating the creation of optimization structures, plan generation, beam placement, and setting of the optimization constraints and the stand-alone executable performing successive optimizations. Ten patients previously treated in our clinic with VMAT TBI were used to evaluate the efficacy of the proposed autoplanning process. Paired t tests were used to compare the dosimetric indices of the produced auto plans to the manually generated clinical plans. In addition, 3 physicians were asked to evaluate the manual and autoplans for each patient in a blinded retrospective review., Results: No significant differences were observed between the manual and autoplan global D max (P < .893), planning target volume V110% (P < .734), kidneys D mean (P < .351), and bowel D max (P < .473). Significant decreases in the D mean to the lungs and lungs-1cm (ie, lungs with 1-cm inner margin) volumes of 5.4% ± 6.4% (P < .024) and 6.8% ± 7.4% (P < .017), respectively, were obtained with the autoplans compared with the manual plans. The autoplans were selected 77% of the time by the reviewing physicians as equivalent or superior to the manual plans. The required time for treatment planning was estimated to be 2 to 3 days for the manual plans compared with approximately 3 to 5 hours for the autoplans., Conclusions: Large reductions in planning time without sacrificing plan quality were obtained using the developed autoplanning process compared with manual planning, thus reducing the required effort of the treatment planning team. Superior lung sparing with the same target coverage and similar global D max were observed with the autoplans as compared with the manual treatment plans. The developed scripts have been made open-source to improve access to VMAT TBI at other institutions and clinics., (Copyright © 2021 American Society for Radiation Oncology. Published by Elsevier Inc. All rights reserved.)