Mathen P, Krauze AV, Rowe L
… +11 more, Chaudhry H, Mackey M, Cooley-Zgela T, Huang E, Shankavaram U, Zalewski C, Snow J, Quezado M, Wu J, Smart D, Camphausen K
Pract Radiat Oncol
· 2026 · PMID 41651156
·
Full text
PURPOSE: A dose-escalation trial of reirradiation (reRT) was conducted in patients with a diagnosis of recurrent glioblastoma (rGBM) to increase the total overall dose given to the tumor without increasing toxicity. The...PURPOSE: A dose-escalation trial of reirradiation (reRT) was conducted in patients with a diagnosis of recurrent glioblastoma (rGBM) to increase the total overall dose given to the tumor without increasing toxicity. The primary objective of this study was to establish the maximum tolerated dose (MTD) for reRT in patients with rGBM. METHODS AND MATERIALS: A phase 1 dose-escalation study using a "3 plus 3" design aimed at identifying reRT MTD with secondary study endpoints of overall survival, progression-free survival, Health-Related Quality of Life, and neurocognitive outcomes. Patients with histologically proven rGBM, Karnofsky Performance Status ≥70, and >12 months since standard chemoradiation, were enrolled in the study. Patients received daily radiation therapy, 5 fractions per week, with dose levels (DLs) (total radiation dose [Gy]/number fractions): DL1 1(35/10), DL2 (42/12), and DL3 (49/14). Response and progression were defined as per Response Assessment in Neuro-Oncology criteria. Neurocognition and patient-reported outcomes were obtained before reRT, at completion of treatment and at follow-up intervals. RESULTS: Fourteen patients were enrolled (64% male, median Karnofsky Performance Status 80 [range, 70-90], median age 54 [range, 38-65]) in DL1(3), DL2(6), and DL3(5). The median time between upfront radiation therapy to completion of reRT was 47.2 months (range, 12.6-93.5 months) with patients enrolled from 2016 to 2022. Median progression-free survival was 5.09 months (3.5, 7.2, and 5.2 months for DL 1, 2, and 3, respectively). Overall survival was 10.3 months (6.1, 14.4, and 13.3 months for DL 1, 2, and 3, respectively). No treatment-related toxicity was observed for DLs 1 and 2. In DL3, 3 of 5 patients experienced neurologic decline without prior radiographic evidence of tumor and were therefore designated as grade 3 treatment-related toxicity. However, no dose-limiting toxicity was observed at any DL. CONCLUSIONS: Results of the trial reveal 4200 cGy in 12 fractions as the MTD for the group of patients with rGBM.
PURPOSE: This study evaluates a 3-step image guidance strategy (bone-prostate-rectal anterior wall alignment) to reduce posterior clinical target volume-planning target volume (CTV-PTV) margins in hypofractionated prosta...PURPOSE: This study evaluates a 3-step image guidance strategy (bone-prostate-rectal anterior wall alignment) to reduce posterior clinical target volume-planning target volume (CTV-PTV) margins in hypofractionated prostate radiation therapy while preserving target coverage and minimizing rectal toxicity. METHODS AND MATERIALS: Twenty-three patients (575 daily cone beam computed tomography scans) underwent a 3-step alignment protocol: bony alignment, prostate soft-tissue matching, and rectal anterior wall fine-tuning. A dose calculation and hybrid deformable image registration-based workflow was created to accumulate the delivered dose. A 5-mm CTV-PTV margin (0 mm posteriorly) with 70 Gy/25 fractions and strict rectal constraints was used. The deformable image registration uncertainty has been thoroughly evaluated, covering geometric indicators, deformation vector field physical properties, spatial uncertainty, and dosimetric uncertainty indicators. Normal tissue complication probability for grade ≥2 gastrointestinal (GI) and genitourinary (GU) toxicity was calculated using the Lyman-Kutcher-Burman model. Statistical comparisons employed paired t-tests or Wilcoxon rank tests (P < .05). RESULTS: The dice similarity coefficient for CTV, rectum, and bladder exceeded 0.8, with mean distance to agreement under 3 mm. Jacobian determinant analysis showed biomechanical validity, with most voxels deforming within physiological ranges (92.23% for CTV, 89.63% for rectum, and 88.96% for bladder) and no nonphysical deformations. The distance discordance metric varied from 0.01 mm to 10.25 mm, and the δ index showed a 90.04% average passing rate within the PD80%. Compared to prostate-only alignment, rectal normal tissue complication probability was significantly reduced with the 3-step strategy (7.95% vs 13.61%, P < .01), with comparable CTV coverage (D95%:69.98 Gy delivered vs 70.98 Gy planned, P = .08). Deformable dose accumulation confirmed adequate dominant intraprostatic lesion (DIL) coverage (median D100 %: 71.51 Gy), except for DILs <0.7 mm from the rectal wall, or the rectal volume overlapping with DIL (DIL extends uniformly outward by 2 cm) >1.5 cm³ (requiring 2-3 mm margin expansion). CONCLUSIONS: A 3-step image guidance protocol enhanced rectal protection while maintaining target coverage compared to prostate-only alignment. Reducing the posterior PTV margin preserved CTV coverage, but DIL coverage varied by location. If the DIL is less than 0.7 mm from the rectum or overlaps more than 1.5 cm³ within 2 mm of the rectum, the reduced margin may not be suitable, potentially compromising DIL coverage, suggesting the need for personalized margins and adaptive radiation therapy to prevent underdosage.
A novel number-color code system was developed to enhance brachytherapy catheter identification. Radiopaque buttons with unique number-color combinations and number tags were used for freehand and template-based catheter...A novel number-color code system was developed to enhance brachytherapy catheter identification. Radiopaque buttons with unique number-color combinations and number tags were used for freehand and template-based catheters, respectively, replacing handwritten adhesive labels. A multidisciplinary survey was conducted to assess its accuracy, ease of use, speed, and user confidence and compare the new and previous methods after 1 year on a five-point Likert scale. Twenty-two staff members (5 radiation oncologists, 7 radiation therapy technologists, 4 nurses, 5 medical physicists, and 1 dosimetrist) participated. No incorrect identification was reported with either method. Personnel with direct applicator contact rated the new system higher on all aspects for freehand catheters. Medical physicists and dosimetrists also gave higher ratings but noted the radiologic invisibility of the colors and suggested shape coding. The most common issue was button positioning. For template-based catheters, number tags were preferred over adhesive labels. To address legibility issues, participants suggested enlarging tags or engraving numbers. The findings indicate that our novel number-color code system is simple and well-accepted by users. Further studies should define objective measures and develop more robust identification labels.
Arifin AJ, Bishop AJ, Mitra D
… +14 more, Yoder A, Araujo DM, Haddad EFN, Ratan R, Livingston JA, Lewis VO, Lin PP, Moon BS, Keung EZ, Roland CL, Scally CP, Mericli AF, Guadagnolo BA, Farooqi AS
Pract Radiat Oncol
· 2026 · PMID 41579133
·
Full text
PURPOSE: Select patients with metastatic soft tissue sarcoma (STS) may benefit from more aggressive treatment of their primary tumor. We report on the use of combined modality treatment (CMT) using preoperative radiation...PURPOSE: Select patients with metastatic soft tissue sarcoma (STS) may benefit from more aggressive treatment of their primary tumor. We report on the use of combined modality treatment (CMT) using preoperative radiation therapy (RT) followed by surgery to improve local control. METHODS AND MATERIALS: We retrospectively reviewed the data of 19 patients with metastatic STS consecutively treated at our institution with CMT between 2018 and 2023. All patients received moderately hypofractionated 40.05 Gy in 15 fractions followed by surgery. Patients were selected for CMT based on factors that were likely to predict longer survival despite having metastatic disease such as oligometastatic disease (≤5 lesions) and favorable response to systemic therapy. RESULTS: The median size of the primary tumor was 7.6 cm (IQR, 4.4-12.7 cm). Fourteen patients (74%) received systemic therapy immediately before (n = 10) or after (n = 4) CMT. Seven patients (37%) underwent additional metastasis-directed local therapy following CMT to other sites. Pain reduction after CMT was documented in 89% of patients who presented with pain (n = 8 of 9). Median follow-up was 21 months. Two-year local recurrence-free survival, progression-free/distant recurrence-free survival, and overall/cancer-specific survival were 92%, 29%, and 65%, respectively. One patient (5%) had local recurrence. For patients who were not planned to have adjuvant systemic therapy, median systemic therapy-free survival was 15 months. The rate of wound complications within 120 days of surgery was 16%. No planned adjuvant therapy was delayed because of wound complications; all patients commenced systemic therapy within 3 months of surgery. The rate of late RT toxicities was 26%; there were no grade ≥3 late toxicities. CONCLUSIONS: For properly selected patients with metastatic STS with good performance status and long expected survival, a CMT strategy for the primary tumor with moderately hypofractionated preoperative RT offers favorable local control, low toxicity, and pain mitigation without significant effect on systemic therapy resumption.
PURPOSE: Standardization in clinical workflows is widely recognized as a driver of safety, efficiency, and consistency. The challenge for modern practice is determining the appropriate degree and rigidity of standardizat...PURPOSE: Standardization in clinical workflows is widely recognized as a driver of safety, efficiency, and consistency. The challenge for modern practice is determining the appropriate degree and rigidity of standardization, especially as automation and adaptive technologies reshape workflows. METHODS AND MATERIALS: This Special Article synthesizes literature from radiation oncology, human factors engineering, and safety science to evaluate the balance between standardization and adaptability. We use the Law of Requisite Variety as a conceptual framework, supplemented by examples from quality assurance, adaptive radiation therapy, and emerging technologies. RESULTS: Well-designed standards enhance reliability, reduce variability, and facilitate training and compliance. However, excessive standardization may create brittle systems incapable of managing novel situations, whereas insufficient standardization increases variability and risk of preventable incidents. Examples illustrate how rigid quality assurance protocols can limit flexibility in addressing non-routine clinical scenarios, and how overly prescriptive adaptive workflows can hinder responsiveness to patient-specific needs. CONCLUSIONS: Radiation oncology requires a dynamic balance between standardization and adaptability. Overstandardization can compromise resilience; understandardization can erode consistency. Applying the Law of Requisite Variety can help identify when to enforce rigid standards and when to preserve flexibility, ensuring both safety and efficiency. This approach supports informed policy-making, technology integration, and sustainable quality improvement in clinical physics practice.
PURPOSE: This dose-volume histogram (DVH) compendium shares the knowledge and resources compiled by disease-site experts during an immense undertaking by the Veterans Affairs (VA) and American Society for Radiation Oncol...PURPOSE: This dose-volume histogram (DVH) compendium shares the knowledge and resources compiled by disease-site experts during an immense undertaking by the Veterans Affairs (VA) and American Society for Radiation Oncology (ASTRO) to develop performance indicators for radiation therapy as part of quality surveillance. The guidance for breast, head and neck, liver, lung, prostate, and rectal cancers supports physician decision-making during dosimetric treatment planning, directs the reader to additional resources, and contributes to the evolution of DVH metrics for external beam radiation therapy. METHODS AND MATERIALS: DVH tables were developed for each disease site relating to the most common dose/fractionation regimens used in VA and non-VA radiation oncology centers nationwide. Dosimetric values with validation through prior clinical data and those used in ongoing multisite trials were prioritized, with references listed in the tables. In scenarios with a paucity of data for specific constraints, the disease-site panels discussed and agreed on appropriate clinical guidance. After panel discussion, each metric was voted on to obtain panel consensus. Panel consensus was evaluated with a modified Delphi approach using a prespecified threshold of ≥75% of raters who agree or strongly agree to establish consensus via a confidential survey. Where the content did not meet this threshold, it was removed or revised. Significant revisions went back to the full disease-site panel for review, approval, and a final consensus vote. RESULTS: The dose constraints are the result of quality measure development between the VA and ASTRO. They represent the body of work thus far, with the goal of expanding future resources to include other disease sites. There is still work to be done to optimize dose goals and constraints for target volumes and normal tissues. Different methodologies for calculating doses have produced varying data, and ongoing efforts will harmonize the lack of concordance where possible. Wide variation when reporting on toxicities and efforts to standardize provide an opportunity for future trial data to add to the depth of knowledge. This DVH compendium is pragmatic and reflective of general practice and established treatment regimens. Having accessible default constraints supports standardization and will help improve the quality of treatment planning and radiation delivery for all patients.
Greenwald LM, Williams A, Downes MH
… +14 more, Reidenberg JS, Collins V, Bane O, Bowen S, Okorom A, Dickstein DR, Garcia-Barros M, Brody R, Hannan JL, Thor M, Lymberis S, Hindman N, Chubak B, Marshall DC
Pract Radiat Oncol
· 2026 · PMID 41569221
·
Full text
For females with genitopelvic cancers, the impacts of radiotherapy on erectile tissue function and related sexual health outcomes are understudied. To inform more equitable research and clinical practice in radiotherapy,...For females with genitopelvic cancers, the impacts of radiotherapy on erectile tissue function and related sexual health outcomes are understudied. To inform more equitable research and clinical practice in radiotherapy, there is a need for education and a standardized approach to understand the bulboclitoris -- the female erectile organ primarily responsible for arousal and orgasm. This topic discussion summarizes the literature and provides a multidisciplinary expert discussion of anatomic and physiologic considerations of the bulboclitoris within the biopsychosocial framework of female sexual function and in the context of radiotherapy. With input from anatomists, physiologists, pathologists, radiologists, radiation oncologists, and patient advocates, recommendations are provided to understand correlative functional bulboclitoris anatomy and histology, localization of bulboclitoris anatomy on CT and MR imaging, measurement of bulboclitoris-related sexual function outcomes, as well as the need for developing new dose-volume constraints to limit radiation toxicity and sexual dysfunction. These recommendations aim to promote collaborative scientific investigations related to the bulboclitoris in radiotherapy, which are crucial for generating fundamental evidence to advance prospective evaluation, prevention and mitigation strategies, to improve oncologic care and sexual health outcomes in individuals with a bulboclitoris.
PURPOSE: Image guided stereotactic body radiation therapy (SBRT) serves as a key local treatment for liver metastases. As a next-generation technology, magnetic resonance guided SBRT (MRgRT) offers theoretical advantages...PURPOSE: Image guided stereotactic body radiation therapy (SBRT) serves as a key local treatment for liver metastases. As a next-generation technology, magnetic resonance guided SBRT (MRgRT) offers theoretical advantages over computed tomography guided SBRT for the management of liver metastases. However, clinical evidence regarding the efficacy of MRgRT for colorectal cancer liver metastases (CRLM) remains lacking. METHODS AND MATERIALS: This retrospective study included patients with CRLM who underwent MRgRT at a single institution between September 2021 and December 2023. Local control (L), distant hepatic control, progression-free survival, and overall survival (OS) were estimated using the Kaplan-Meier method and analyzed using statistical software (R and SPSS). Adverse events were graded according to the Common Terminology Criteria for Adverse Events version 5.0. RESULTS: Overall, 51 targets (planning target volumes) in 49 patients with CRLM were treated with MRgRT. The median lesion diameter was 1.9 cm (range, 0.5-6.4 cm), whereas the median prescribed dose to the gross tumor volume was 57 Gy (range, 48-60 Gy). The median follow-up duration was 20.1 months. Among the 51 targets, 3 experienced local failure. None of the patients developed grade >2 radiation-related toxicity. The LC rates at 12 and 24 months were 93.8% and 86.6%, respectively. The distant hepatic control rates at 12 and 24 months were 52.5% and 49.2%, respectively. The progression-free survival rates at 12 and 24 months were 31.5% and 25.5%, whereas the OS rates at 12 and 24 months were 91.4% and 84.0%, respectively. CONCLUSIONS: MRgRT achieved favorable LC and OS rates in the treatment of CRLM with minimal toxicity, demonstrating its potential for broader clinical application. Further studies with larger sample sizes and long-term follow-up are warranted to validate survival outcomes and assess late-onset toxicities.
Pelvic organ prolapse occurring shortly after hysterectomy is rare but may complicate adjuvant external beam radiation therapy (EBRT) in endometrial cancer. Delivering EBRT in the presence of prolapse may increase radiat...Pelvic organ prolapse occurring shortly after hysterectomy is rare but may complicate adjuvant external beam radiation therapy (EBRT) in endometrial cancer. Delivering EBRT in the presence of prolapse may increase radiation exposure to adjacent organs and treatment-related toxicity, whereas surgical correction can delay adjuvant therapy. We describe a technically feasible, nonsurgical approach using a vaginal pessary to restore pelvic anatomy and facilitate EBRT planning. Pessary-assisted repositioning improved target delineation and reduced high-dose exposure to the bladder, vagina, and rectum without delaying treatment or causing toxicity. This Technical Report highlights a simple, patient-centered strategy to optimize radiation therapy delivery in complex posthysterectomy anatomy.
PURPOSE: Modesty affects patient experience of health care and health outcomes. Radiation therapy often requires body exposure. Little is known about modesty and patient unease during radiation therapy across diverse pop...PURPOSE: Modesty affects patient experience of health care and health outcomes. Radiation therapy often requires body exposure. Little is known about modesty and patient unease during radiation therapy across diverse populations and treatment sites. This study examined current practice and patient perceptions regarding modesty and associated unease during radiation therapy to the thorax and pelvis areas. METHODS AND MATERIALS: A 38-question survey was distributed to patients undergoing thoracic or pelvic radiation therapy across 4 centers. Item response theory analyzed the psychometric properties of unease. A structural equation model identified factors associated with unease. Summative content analysis of free-text responses was conducted. RESULTS: A total of 312 participants responded: 76% were female, 69% received thoracic radiation therapy, 43% were foreign-born, and 65% spoke a language other than English. Ten percent of participants indicated they were never informed about the need to undress, and 26% received written information regarding the need to undress. This survey was reliable for patients with average or above levels of unease (item response theory theta values > -0.3). 67.5% of the variance of unease in the treatment room was explained by unease in the waiting room, gender of treating staff, and baseline levels of modesty unease (P < .001). Staff kindness and professionalism were connected to patient ease in the treatment room. Functionality of treatment garments and waiting spaces were also themes connected to patient ease (f = 41% and 46%, respectively). CONCLUSIONS: Patient modesty can affect unease in radiation therapy waiting and treatment rooms. This is the first study to demonstrate this in both a multicultural population and across different anatomic treatment sites. Simply worded questionnaires can distinguish responders with higher than average unease. Personalisable treatment garment and waiting space options are recommended. Patient education materials can be improved by clearly outlining the requirement for patients to undress during treatment delivery.
McGunigal M, Sherertz T, Musa F
… +14 more, Barry P, Franco I, Glaser S, Goldman K, Grossman CE, Lin L, Portelance L, Venkatesulu BP, Silva SR, Simons E, Singh S, Small W, Suneja G, Jhingran A
PURPOSE: Locally advanced endometrial cancers are heterogeneous and challenging to treat. Immunotherapy has transformed the treatment landscape. Given the complexity of tailoring adjuvant treatment recommendations, the m...PURPOSE: Locally advanced endometrial cancers are heterogeneous and challenging to treat. Immunotherapy has transformed the treatment landscape. Given the complexity of tailoring adjuvant treatment recommendations, the multidisciplinary American Radium Society Gynecologic Cancer Panel created evidence-based guidelines for the management of locally advanced endometrial adenocarcinoma. METHODS AND MATERIALS: Search terms, key questions, and associated clinical case variants were formed by panel consensus. A review of the literature was conducted from January 1, 1996, to March 5, 2024, using the Preferred Reporting Items for Systematic Review and Meta-analyses guidelines to systematically search the PubMed, Embase, and Web of Science databases to retrieve a comprehensive set of relevant articles. A well-established methodology (modified Delphi) was used by the expert panel to rate the appropriate use of procedures. RESULTS: Evidence for key questions in advanced-stage endometrial cancer was examined. Two rounds of voting were completed pertaining to the appropriateness of key management decisions for 4 clinical variants. Optimal adjuvant treatment is based on pathologic and molecular risk factors, and typically consists of combined modality therapy, with both chemotherapy and radiation, to minimize the risk of local and distant recurrence; there are no prospective data on optimal sequencing. Molecular data from PORTEC-3 highlights that adding chemotherapy to radiation is especially crucial for p53 abnormal tumors. Inclusion criteria for the NRG-GY018/RUBY trials can guide appropriateness of incorporating immunotherapy, which should be considered especially in mismatch repair-deficient (dMMR) patients. Radiation fields should be extended to include para-aortic lymph nodes in IIIC2 disease. Within pelvic radiation, intensity modulated radiation therapy is the preferred technique to mitigate toxicity as supported by prospective data. CONCLUSION: Selecting appropriate adjuvant therapies for advanced-stage endometrial cancer is nuanced. Further prospective studies harnessing molecular markers as therapeutic targets will help advance and optimize therapies for more personalized treatment of this complex disease.
PURPOSE: The deep inspiration breath-hold (DIBH) technique for left breast cancer reduces cardiac radiation exposure but requires additional DIBH computed tomography (CT) scans to confirm patient suitability, increasing...PURPOSE: The deep inspiration breath-hold (DIBH) technique for left breast cancer reduces cardiac radiation exposure but requires additional DIBH computed tomography (CT) scans to confirm patient suitability, increasing radiation dose and costs. We propose an innovative screening approach using high-performance DIBH-CT synthesis and quantitative dose prediction. METHODS AND MATERIALS: A 2-stage model was first developed: (1) a synthetic DIBH-CT (sDIBH-CT) was generated from free-breathing CT (FB-CT) via an attention U-Net, and (2) the synthetic model was retrained using FB-CT and patient-specific DIBH orthogonal projections of test patients to obtain a refined sDIBH-CT. The FB-CT was then registered to the refined sDIBH-CT and the consequent deformation vector field was used to obtain the final predicted DIBH-CT (pDIBH-CT) and associated contours. A dose prediction model estimated the mean heart dose (MHD) for pDIBH-CT. Registration accuracy was quantified by the Dice similarity coefficient, while image quality was assessed using the mean absolute error. Furthermore, MHD reduction thresholds were established to stratify DIBH-suitable patients: patients with FB-MHD >4 Gy required ≥30% MHD reduction with DIBH, whereas those with FB-MHD ≤4 Gy required ≥50% reduction. The retrospective study was evaluated using 178 patients treated with left-sided breast radiation therapy. RESULTS: The mean absolute error between FB-CT and DIBH-CT decreased from 178.49 ± 41.95 Hounsfield units (HU) to 55.19 ± 14.10 HU after generating pDIBH-CT. The Dice similarity coefficient increased from 0.50 ± 0.19 to 0.87 ± 0.05 for CTV, 0.59 ± 0.17 to 0.89 ± 0.04 for PTV, 0.79 ± 0.05 to 0.92 ± 0.01 for the heart, and 0.81 ± 0.04 to 0.96 ± 0.01 for the lungs. The accuracy of the radiation therapy strategy screening reached 86.7% (13/15), with the predicted outcomes closely matching the actual DIBH treatment results. CONCLUSIONS: We propose a rapid screening strategy for assessing DIBH suitability for patients treated with left-sided breast radiation therapy. This strategy has the potential to greatly optimize clinical workflow and reduce the burden on both patients and health care providers.
PURPOSE: Axillary substructures may contribute to the development of breast cancer-related lymphedema (BCRL). This study aimed to compare dose-volume parameters of various substructures to identify high-risk regions asso...PURPOSE: Axillary substructures may contribute to the development of breast cancer-related lymphedema (BCRL). This study aimed to compare dose-volume parameters of various substructures to identify high-risk regions associated with BCRL and to evaluate the clinical applicability of these findings. METHODS AND MATERIALS: Cohort-Initial included 336 patients with pT1-3N0-1M0 breast cancer who underwent mastectomy or lumpectomy with axillary lymph node dissection (ALND) and regional nodal irradiation (RNI) between August 2018 and February 2021. The Norman questionnaire was used to assess BCRL. Thirteen dose-volume parameters across 8 axillary substructures were assessed for association with BCRL. Cohort-Recurrence comprised 50 consecutive ALND-treated patients with regional nodal recurrence diagnosed using positron emission tomography/computed tomography, used to evaluate the recurrence risk in the candidate substructures. Cohort-Reoptimization involved 20 patients from the Cohort-Initial who received excessive radiation doses in the candidate substructure. Their treatment plans were reoptimized to assess the feasibility of dose reduction while maintaining target coverage and organ dose. RESULTS: The patient-reported cumulative incidence of BCRL was 33.9% during a median follow-up of 60 months. Significant baseline risk factors included body mass index ≥ 27.18 kg/m, tumor size ≥ 1.9 cm, premenopausal status, and ≥ 18 lymph nodes removed (all P < .05). The most significant dosimetric parameter was axillary-lateral thoracic vessel juncture (ALTJ)-V35 ≥ 79.2%. A predictive nomogram incorporating these clinicopathologic factors and the ALTJ parameter was developed with reasonable accuracy, as confirmed by self-training (area under the curve value, 0.780) and internal validation (area under the curve value, 0.769). None of the 196 fluorodeoxyglucose-avid regional nodes in Cohort-Recurrence were located within the ALTJ. Reoptimization of ALTJ-V35 was feasible without compromising the radiation therapy plan quality. CONCLUSIONS: ALTJ-V35 < 79.2% may serve as a recommended dose constraint for patients undergoing RNI after ALND. Avoiding excessive radiation to the ALTJ is clinically feasible and safe, potentially mitigating BCRL risk without compromising dose coverage to high-risk nodal regions.
PURPOSE: Current electron field shaping methods, such as milled copper cutouts and Cerrobend plates, are limited by toxic materials, recurring costs, and long turnaround times. To circumvent these issues, we designed a 3...PURPOSE: Current electron field shaping methods, such as milled copper cutouts and Cerrobend plates, are limited by toxic materials, recurring costs, and long turnaround times. To circumvent these issues, we designed a 3-dimensional-printed electron multileaf collimator (eMLC) that uses tungsten-infused polyethylene terephthalate glycol (W-PETG), a filament developed specifically for radiation therapy, to create the leaves. This study described the feasibility assessment of this device to shape electron fields. METHODS AND MATERIALS: We first characterized the attenuation properties of W-PETG using stacks of variable thickness blocks (0.1-1 cm, flat 10 × 10 cm) placed in a solid water phantom with a parallel plate chamber. Attenuation of 6 and 15 MeV electron beam energies was tested using various plate thicknesses. A prototype eMLC was designed to mount within a standard Elekta 14 × 14 cm² cone. The carriage was printed using generic PETG; interlocking leaves were printed using W-PETG. Interleaf and leaf-end leakage were evaluated using 1000 monitor units (MU) delivered through closed leaves. A clinical Cerrobend field was recreated with the eMLC, and both were compared using radiochromic film exposed to 200 MU using 6 and 15 MeV electron beams. RESULTS: W-PETG blocks of 1 cm thickness reduced 6 and 15 MeV electron beams to below 5% transmission. No measurable interleaf or end-to-end leaf leakage was detected at either energy using 1000 MU exposures. The eMLC resulted in a dose distribution nearly identical to Cerrobend. Compared with Cerrobend, the eMLC-generated fields demonstrated approximately 15% smaller penumbra and sharper field edges. CONCLUSIONS: This novel 3-dimensional-printed eMLC using W-PETG provides dose-shaping characteristics comparable with conventional cutouts, with no detectable leakage and improved edge definition. Fabricated with consumer-grade equipment, this device provides reusable, customizable field shapes that may be suitable for clinical use. Further study of its validation and implementation into clinical workflows is warranted.