Brachial Plexopathy After Single-Fraction Stereotactic Body Radiation Therapy in Apical Lung Tumors.

Purpose: The objective of this study was to evaluate the incidence of brachial plexus injury (BPI) after single-fraction stereotactic body radiation therapy (SBRT) to apical lung tumors.

Methods And Materials: A retrospective cohort analysis was performed of all patients treated with single-fraction lung SBRT at our institution from 2007 to 2022. Apical tumors were identified as those with an epicenter located above the arch of the aorta.

Practice Patterns of Pediatric Total Body Irradiation Techniques: A Children's Oncology Group Survey.

Purpose: The aim of this study was to examine current practice patterns in pediatric total body irradiation (TBI) techniques among COG member institutions.

Methods And Materials: Between November 2019 and February 2020, a questionnaire containing 52 questions related to the technical aspects of TBI was sent to medical physicists at 152 COG institutions. The questions were designed to obtain technical information on commonly used TBI treatment techniques.

Exceeding Radiation Dose to Volume Parameters for the Proximal Airways with Stereotactic Body Radiation Therapy Is More Likely for Ultracentral Lung Tumors and Associated with Worse Outcome.

The preferred radiotherapeutic approach for central (CLT) and ultracentral (UCLT) lung tumors is unclear. We assessed the toxicity and outcomes of patients with CLT and UCLT who underwent definitive five-fraction stereotactic body radiation therapy (SBRT). We reviewed the charts of patients with either CLT or UCLT managed with SBRT from June 2010-April 2019.

Autosegmentation of cardiac substructures in respiratory-gated, non-contrasted computed tomography images.

Background: Radiation dose to specific cardiac substructures can have a significant on treatment related morbidity and mortality, yet definition of these structures is labor intensive and not standard. Autosegmentation software may potentially address these issues, however it is unclear whether this approach can be broadly applied across different treatment planning conditions. We investigated the feasibility of autosegmentation of the cardiac substructures in four-dimensional (4D) computed tomography (CT), respiratory-gated, non-contrasted imaging.

Development and Validation of a Clinically Relevant Workflow for MR-Guided Volumetric Arc Therapy in a Rabbit Model of Head and Neck Cancer.

There is increased interest in the use of magnetic resonance imaging (MRI) for guiding radiation therapy (RT) in the clinical setting. In this regard, preclinical studies can play an important role in understanding the added value of MRI in RT planning. In the present study, we developed and validated a clinically relevant integrated workflow for MRI-guided volumetric arc therapy (VMAT) in a VX2 rabbit neck tumor model of HNSCC.

Dosimetric Implications of Number of Breathing Phases Used in the Definition of Internal Target Volume [ITV] in the Treatment of Non-Small Cell Lung Cancers Using Stereotactic Body Radiation Therapy (SBRT).

Determination of intrafraction motion in stereotactic body radiation therapy (SBRT) of non-small-cell lung cancer (NSCLC) usually involves generating an internal target volume (ITV) based on target segmentation in every one of the 10 phases of a 4-dimensional computed tomography (4DCT) dataset which increases dosimetry work load substantially. This study explores the feasibility of using a smaller number of phases to compile an ITV to get equivalent results. Twenty-five lung cancer patients treated with SBRT were retrospectively assessed.

A pilot study of stereotactic body radiation therapy (SBRT) after surgery for stage III non-small cell lung cancer.

Background: Standard therapy for stage III non-small cell lung cancer with chemotherapy and conventional radiation has suboptimal outcomes. We hypothesized that a combination of surgery followed by stereotactic body radiation therapy (SBRT) would be a safe alternative.

Methods: Patients with stage IIIA (multistation N2) or IIIB non-small cell lung cancer were enrolled from March 2013 to December 2015.

Technical and dosimetric implications of respiratory induced density variations in a heterogeneous lung phantom.

Background: Stereotactic Body Radiotherapy (SBRT) is an ablative dose delivery technique which requires the highest levels of precision and accuracy. Modeling dose to a lung treatment volume has remained a complex and challenging endeavor due to target motion and the low density of the surrounding media. When coupled together, these factors give rise to pulmonary induced tissue heterogeneities which can lead to inaccuracies in dose computation.

Comparison of Single- and Five-fraction Regimens of Stereotactic Body Radiation Therapy for Peripheral Early-stage Non-small-cell Lung Cancer: A Two-institution Propensity-matched Analysis.

Purpose: To evaluate differences in local control (LC), disease-specific (DC), and overall survival (OS) of patients with early-stage non-small-cell lung cancer (NSCLC) treated with single- (SF) versus 5-fraction (FF) stereotactic body radiation therapy (SBRT) at 2 institutions.

Patients And Methods: Peripheral early-stage NSCLC cases treated with a median dose of 30 Gy in SF or a median dose of 50 Gy in FF were included per institutional practice. Kaplan-Meier and Cox models were used to assess survival.

An investigation into the range dependence of target delineation strategies for stereotactic lung radiotherapy.

Background: The "gold standard" approach for defining an internal target volume (ITV) is using 10 gross tumor volume (GTV) phases delineated over the course of one respiratory cycle. However, different sites have adopted several alternative techniques which compress all temporal information into one CT image set to optimize work flow efficiency. The purpose of this study is to evaluate alternative target segmentation strategies with respect to the 10 phase gold standard.

Minimally invasive rib-sparing video-assisted thoracoscopic surgery resections with high-dose-rate intraoperative brachytherapy for selected chest wall tumors.

Background: By avoiding chest wall resection, iridium-192 (Ir-192) high-dose-rate (HDR) intraoperative brachytherapy (IOBT) and video-assisted thoracoscopic surgery (VATS) might improve outcomes for high-risk patients requiring surgical resection for pulmonary malignancy with limited pleura and/or chest wall involvement.

Methods And Materials: Seven patients with non-small cell lung cancer involving the pleura or chest wall underwent VATS pulmonary resections combined with HDR IOBT. After tumor extraction, an Ir-192 source was delivered via a Freiburg applicator to intrathoracic sites with potential for R1-positive surgical margins.

A novel method for vaginal cylinder treatment planning: a seamless transition to 3D brachytherapy.

Purpose: Standard treatment plan libraries are often used to ensure a quick turn-around time for vaginal cylinder treatments. Recently there is increasing interest in transitioning from conventional 2D radiograph based brachytherapy to 3D image based brachytherapy, which has resulted in a substantial increase in treatment planning time and decrease in patient through-put. We describe a novel technique that significantly reduces the treatment planning time for CT-based vaginal cylinder brachytherapy.

EPID dosimetry for pretreatment quality assurance with two commercial systems.

This study compares the EPID dosimetry algorithms of two commercial systems for pretreatment QA, and analyzes dosimetric measurements made with each system alongside the results obtained with a standard diode array. 126 IMRT fields are examined with both EPID dosimetry systems (EPIDose by Sun Nuclear Corporation, Melbourne FL, and Portal Dosimetry by Varian Medical Systems, Palo Alto CA) and the diode array, MapCHECK (also by Sun Nuclear Corporation). Twenty-six VMAT arcs of varying modulation complexity are examined with the EPIDose and MapCHECK systems.

Dosimetric impact of image artifact from a wide-bore CT scanner in radiotherapy treatment planning.

Purpose: Traditional computed tomography (CT) units provide a maximum scan field-of-view (sFOV) diameter of 50 cm and a limited bore size, which cannot accommodate a large patient habitus or an extended simulation setup in radiation therapy (RT). Wide-bore CT scanners with increased bore size were developed to address these needs. Some scanners have the capacity to reconstruct the CT images at an extended FOV (eFOV), through data interpolation or extrapolation, using projection data acquired with a conventional sFOV.

Experimental measurements and Monte Carlo simulations of dose perturbation around a nonradioactive brachytherapy seed due to 6- and 18-MV photons.

Purpose: Radioactive seeds used in permanent prostate brachytherapy are composed of high-Z metals and may exceed 100 in a patient. If supplemental external beam treatment is administered afterward, the seeds may cause substantial dose perturbation, which is being investigated in this article.

Methods And Materials: Film measurements using 6-MV beam were primarily carried out using Kodak XV2 film layered above and below a nonradioactive iodine-125 ((125)I) seed.

Target and peripheral dose from radiation sector motions accompanying couch repositioning of patient coordinates with the Gamma Knife(®) Perfexion(™).

Background: The GammaPlan(™) treatment planning system (TPS) does not fully account for shutter dose when multiple shots are required to deliver a patient's treatment. The unaccounted exposures to the target site and its periphery are measured in this study. The collected data are compared to a similar effect from the Gamma Knife(®) model 4C.

Measurement of dose perturbation around shielded ovoids in high-dose-rate brachytherapy.

Purpose: To analyze the effect of tungsten shields present in a Fletcher-Suit-Delclos ovoid by comparing the dose distribution computed by a treatment planning system (TPS) to the delivered dose distribution measured by radiochromic film dosimetry.

Methods And Materials: Gafchromic/EBT films were carefully wrapped around the caps (diameter 20-25 mm) of shielded as well as unshielded ovoids, including their anterior and posterior ends. The ovoids were irradiated to a dose of 300 cGy using a high-dose rate remote afterloading unit.

Association of Technetium(99m) MAG-3 renal scintigraphy with change in creatinine clearance following chemoradiation to the abdomen in patients with gastrointestinal malignancies.

Background: Information on differential renal function following abdominal chemoradiation is limited. This study evaluated the association between renal function as measured by biochemical endpoints and scintigraphy and dose volume parameters in patients with gastrointestinal malignancies.

Materials And Methods: Patients who received abdominal chemoradiation between 2002 and 2009 were identified for this study.

Intensity modulated radiation therapy in the treatment of esophageal cancer.

Chemoradiation plays a core role in the definitive and preoperative management of esophageal cancer. Remarkable advances in technology now allow for the implementation of intensity modulated radiation therapy (IMRT) to minimize normal organ damage and to maximize coverage of tumorous targets. While IMRT is commonly accepted in the treatment of prostate and head and neck cancers, there have been clinical and dosimetric studies supporting the use of IMRT in esophagus cancer.

Target and peripheral dose during patient repositioning with the Gamma Knife automatic positioning system (APS) device.

The GammaPlan treatment planning system does not account for the leakage and scatter dose during APS repositioning. In this study, the dose delivered to the target site and its periphery from the defocus stage and intershot couch transit (couch motion from the focus to defocus position and back) associated with APS repositioning are measured for the Gamma Knife model 4C. A stereotactic head-frame was attached to a Leksell 16 cm diameter spherical phantom with a calibrated ion chamber at its center.

Optimization of beam angles for intensity modulated radiation therapy treatment planning using genetic algorithm on a distributed computing platform.

Planning intensity modulated radiation therapy (IMRT) treatment involves selection of several angle parameters as well as specification of structures and constraints employed in the optimization process. Including these parameters in the combinatorial search space vastly increases the computational burden, and therefore the parameter selection is normally performed manually by a clinician, based on clinical experience. We have investigated the use of a genetic algorithm (GA) and distributed-computing platform to optimize the gantry angle parameters and provide insight into additional structures, which may be necessary, in the dose optimization process to produce optimal IMRT treatment plans.