Practical Radiation Oncology

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INTRODUCTION: Spatially fractionated radiotherapy (SFRT) techniques produce high-dose peaks and low-dose valleys within a tumor. Lattice stereotactic body radiation therapy (SBRT) is a form a SFRT delivered across five fractions. Due to the high spatial dose gradients associated with SFRT, it is critical for fractionated SFRT patients to be aligned correctly for treatment. Here we investigate the dosimetric impact of daily alignment uncertainty through a dose accumulation study. METHODS: Dose accumulation was retrospectively performed for ten patients enrolled on a Phase I trial...

PURPOSE: Surface-guided radiation-therapy (SGRT) systems are being adopted into clinical practice for patient setup and motion monitoring. However, commercial systems remain cost prohibitive to resource-limited clinics around the world. Our aim is to develop and validate a smartphone-based application using LiDAR cameras (such as on recent Apple iOS devices) for facilitating SGRT in low-resource centers. The proposed SGRT application was tested at multiple institutions, and validated using phantoms and volunteers against various commercial systems to demonstrate feasibility...

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PURPOSE: The purpose of this work is to develop a method to automate the treatment planning process of craniospinal irradiation (CSI) using volumetric modulated arc therapy (VMAT). METHODS AND MATERIALS: Two scripts were developed using the Eclipse Scripting Application Programming Interface (ESAPI) to perform auto-plan preparation and optimization. Ten patients (age, 5-44 years) previously treated at our institution with low dose VMAT-CSI (prescription of 12 Gy) prior to total body irradiation were selected to evaluate the efficacy of the proposed auto-planning process...

INTRODUCTION: The administration of dose-escalated radiation for pancreatic adenocarcinoma remains challenging due to the proximity of dose-limiting stomach and bowel, particularly the duodenum for pancreatic head tumors. We explore whether endoscopic injection of a temporary, absorbable hydrogel into the pancreatico-duodenal (PD) groove is safe and feasible for the purpose of increasing spatial separation between pancreatic head tumors and the duodenum. METHODS: Six patients with localized pancreatic adenocarcinoma underwent endoscopic injection of hydrogel into the PD groove...

PURPOSE: Recently, a randomized trial demonstrated that a hyaluronic acid (HA) spacer placed prior to prostate hypofractionated intensity-modulated radiation therapy improved rectal dosimetry and reduced acute grade 2+ gastrointestinal toxicity. However, 26.5% of patients receiving the spacer experienced a minimal clinically important decline (MCID) in bowel quality-of-life (QOL). The purpose of this study is to evaluate whether certain characteristics of the rectal spacer, as determined on post-implant imaging, were associated with change in bowel QOL at 3-months...

PURPOSE: Historically, toxicity concerns have existed in patients with large prostate glands treated with radiotherapy (RT), particularly brachytherapy. There are questions whether this risk extends to stereotactic body radiation therapy (SBRT). In this retrospective review, we examine clinical outcomes of patients with prostate glands ≥100 cc treated curatively with SBRT. METHODS AND MATERIALS: We retrospectively analyzed a large institutional database to identify patients with histologically confirmed localized prostate cancer in glands ≥100 cc, who were treated with definitive-robotic SBRT...

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PURPOSE/OBJECTIVE(S): Hypofractionated radiation therapy (HFRT) is a common treatment for thoracic tumors, typically delivered as 60 Gy in 15 fractions. We aimed to identify dosimetric risk factors associated with radiation pneumonitis in patients receiving HFRT at 4 Gy per fraction, focusing on lung V20, mean lung dose (MLD), and lung V5 as potential predictors of grade ≥2 pneumonitis. MATERIALS/METHODS: All patients were treated with thoracic HFRT to 60 Gy in 15 fractions or 72 Gy in 18 fractions at a single healthcare system from 2013-2020...

PURPOSE: Lung blocks for total-body-irradiation (TBI) are commonly used to reduce lung dose and prevent radiation pneumonitis. Currently, molten Cerrobend containing toxic materials, specifically lead and cadmium, is poured into molds to construct blocks. Here, we propose a streamlined method to create 3D-printed lung block shells and fill them with tungsten ball-bearings (BBs) to remove lead and improve overall accuracy in the block manufacturing workflow. METHODS AND MATERIALS: 3D-printed lung block shells were automatically generated using an inhouse software, printed, and filled with 2-3mm diameter tungsten BBs...

PURPOSE: This guideline provides evidence-based recommendations on appropriate indications and techniques for partial breast irradiation (PBI) for patients with early-stage invasive breast cancer and ductal carcinoma in situ. METHODS: The American Society for Radiation Oncology (ASTRO) convened a task force to address 4 key questions focused on the appropriate indications and techniques for PBI as an alternative to whole breast irradiation (WBI) to result in similar rates of ipsilateral breast recurrence (IBR) and toxicity outcomes...

PURPOSE: This work aims at reviewing challenges and pitfalls in proton facility design related to equipment upgrade or replacement. Proton therapy was initially developed at research institutions in the 1950s which ushered in the use of hospital-based machines in 1990s. We are approaching an era where older commercial machines are reaching the end of their life and require replacement. The future widespread application of proton therapy depends on cost reduction; customized building design and installation are significant expenses...

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PURPOSE: Flattening filter-free (FFF)-based volumetric modulated arc therapy (VMAT) has been shown to be feasible and significantly improves treatment efficiency and lung protection for synchronous bilateral breast irradiation (SBBI). This research compared the commonly used VMAT field arrangements using FFF beams. METHODS: Twenty-eight patients underwent SBBI were retrospectively enrolled to design irradiation plans using tangential arc VMAT (taVMAT), half arc VMAT (haVMAT), and large arc VMAT (laVMAT)...

OBJECTIVE: Oligometastatic disease has expanded the indications for non-spine bone stereotactic body radiation therapy (NSB SBRT). We investigated whether optical surface monitoring systems (OSMS) could enable tattoo-less set up and substitute for 2D-3D or cone beam computed tomography (CBCT)-based mid-imaging in NSB SBRT. MATERIALS/METHODS: OSMS was incorporated in parallel with an existing workflow using pre-treatment CBCT and mid 2D-3D kV/kV imaging beginning 11/2019...

PURPOSE: The goal of this study was to evaluate the image quality provided by a novel cone beam CT (CBCT) platform (HyperSightTM , Varian Medical Systems), a platform with enhanced reconstruction algorithms as well as rapid acquisition times. Image quality was compared to both status quo CBCT for image guidance, and to fan beam CT (FBCT) acquired on a CT simulator (CTsim). METHODS: In a clinical study, 30 subjects were recruited for whom either deep inspiration (DIBH) or deep exhalation breath hold (DEBH) was used during imaging and radiation treatment of tumors involving liver, lung, breast, abdomen, chest wall and pancreatic sites...

PURPOSE: Artificial intelligence (AI)-based autocontouring in radiation oncology has potential benefits such as standardization and time savings. However, commercial AI solutions require careful evaluation before clinical integration. We developed a multidimensional evaluation method to test pretrained AI-based automated contouring solutions across a network of clinics. METHODS AND MATERIALS: Curated data included 121 patient planning computed tomography (CT) scans with a total of 859 clinically approved contours used for treatment from 4 clinics...

PURPOSE/OBJECTIVES: To prospectively evaluate early and intermediate outcome after APBI in early-stage breast cancer patients. MATERIALS/METHODS: Inclusion criteria were defined according to the APBI ASTRO CONSENSUS STATEMENT. The prescribed dose was 26-28 Gy in 5 fractions on 5 consecutive days. Regular follow-up visits with objective and subjective evaluation of treatment tolerance were performed after 0 and 2 weeks, 6 months and at annual intervals. RESULTS: Between 02/2017-01/2020, 175 patients with breast conserving surgery met the inclusion criteria for APBI...

PURPOSE: Online adaptive radiation therapy (ART) has emerged as a new treatment modality for cervical cancer. Daily online adapting improves target coverage and organ-at-risk (OAR) sparing compared with traditional image guided radiation therapy (IGRT); however, the required resources may not be feasible in a busy clinical setting. Less frequent adapting may still benefit cervical cancer patients due to large volume changes of the uterocervix of the treatment course. In this study, the dosimetry from different online adapt-on-demand schedules was compared...