A Pilot Study of Simulation-Free Hippocampal-Avoidance Whole Brain Radiation Therapy Using Diagnostic MRI-Based and Online Adaptive Planning.

Purpose: We aimed to demonstrate the clinical feasibility and safety of simulation-free hippocampal avoidance whole brain radiation therapy (HA-WBRT) in a pilot study (National Clinical Trial 05096286).

Methods And Materials: Ten HA-WBRT candidates were enrolled for treatment on a commercially available computed tomography (CT)-guided linear accelerator with online adaptive capabilities. Planning structures were contoured on patient-specific diagnostic magnetic resonance imaging (MRI), which were registered to a CT of similar head shape, obtained from an atlas-based database (AB-CT).

Feasibility of surface-guidance combined with CBCT for intra-fractional breath-hold motion management during Ethos RT.

Purpose: High-quality CBCT and AI-enhanced adaptive planning techniques allow CBCT-guided stereotactic adaptive radiotherapy (CT-STAR) to account for inter-fractional anatomic changes. Studies of intra-fractional respiratory motion management with a surface imaging solution for CT-STAR have not been fully conducted. We investigated intra-fractional motion management in breath-hold Ethos-based CT-STAR and CT-SBRT (stereotactic body non-adaptive radiotherapy) using optical surface imaging combined with onboard CBCTs.

trial of simulation-free hippocampal-avoidance whole brain adaptive radiotherapy.

Background And Purpose: Hippocampal-avoidance whole brain radiotherapy (HA-WBRT) can be a time-consuming process compared to conventional whole brain techniques, thus potentially limiting widespread utilization. Therefore, we evaluated the clinical feasibility, via dose-volume metrics and timing, by leveraging a computed tomography (CT)-based commercial adaptive radiotherapy (ART) platform and workflow in order to create and deliver patient-specific, simulation-free HA-WBRT.

Materials And Methods: Ten patients previously treated for central nervous system cancers with cone-beam computed tomography (CBCT) imaging were included in this study.

Clinical application of a template-guided automated planning routine.

Purpose: Determine the dosimetric quality and the planning time reduction when utilizing a template-based automated planning application.

Methods: A software application integrated through the treatment planning system application programing interface, QuickPlan, was developed to facilitate automated planning using configurable templates for contouring, knowledge-based planning structure matching, field design, and algorithm settings. Validations are performed at various levels of the planning procedure and assist in the evaluation of readiness of the CT image, structure set, and plan layout for automated planning.

Technical note: Institutional solution of clinical cine MRI for tumor motion evaluation in radiotherapy.

Purpose: Since 4D-MRI is inadequate to capture dynamic respiratory variations, real-time cinematographic (cine) MRI is actively used in MR-guided radiotherapy (MRgRT) for tumor motion evaluation, delineation, and tracking. However, most radiotherapy imaging platforms do not support the format of cine MRI from clinical MRI systems. This study developed an institutional solution of clinical cine MRI for tumor motion evaluation in radiotherapy applications.

Commissioning a secondary dose calculation software for a 0.35 T MR-linac.

Secondary external dose calculations for a 0.35 T magnetic resonance image-guided radiation therapy (MRgRT) are needed within the radiation oncology community to follow safety standards set forth within the field. We evaluate the commercially available software, RadCalc, in its ability to accurately perform monitor unit dose calculations within a magnetic field.

LITE SABR M1: Planning design and dosimetric endpoints for a phase I trial of lattice SBRT.

Purpose: Lattice stereotactic body radiation therapy (SBRT) is a form of spatially fractionated radiation therapy (SFRT) using SBRT methods. This study reports clinical dosimetric endpoints achieved for Lattice SBRT plans delivering 20 Gy in 5 fractions to the periphery of a tumor with a simultaneous integrated boost (SIB) of 66.7 Gy, as part of a prospective Phase I clinical trial (NCT04133415).

Technical Report: Development and Implementation of an Open Source Template Interpretation Class Library for Automated Treatment Planning.

Purpose: Widespread implementation of automated treatment planning in radiation therapy remains elusive owing to variability in clinic and physician preferences, making it difficult to ensure consistent plan parameters. We have developed an open-source class library with the aim to improve efficiency and consistency for automated treatment planning in radiation therapy.

Methods And Materials: An open-source class library has been developed that interprets clinical templates within a commercial treatment planning system into a treatment plan for automated planning.

Visually guided respiratory motion management for Ethos adaptive radiotherapy.

Purpose: Ethos adaptive radiotherapy (ART) is emerging with AI-enhanced adaptive planning and high-quality cone-beam computed tomography (CBCT). Although a respiratory motion management solution is critical for reducing motion artifacts on abdominothoracic CBCT and improving tumor motion control during beam delivery, our institutional Ethos system has not incorporated a commercial solution. Here we developed an institutional visually guided respiratory motion management system to coach patients in regular breathing or breath hold during intrafractional CBCT scans and beam delivery with Ethos ART.

Evaluation of Motion Compensation Methods for Noninvasive Cardiac Radioablation of Ventricular Tachycardia.

Purpose: Noninvasive cardiac radioablation is increasingly used for treatment of refractory ventricular tachycardia. Attempts to limit normal tissue exposure are important, including managing motion of the target. An interplay between cardiac and respiratory motion exists for cardiac radioablation, which has not been studied in depth.

Spatially fractionated stereotactic body radiation therapy (Lattice) for large tumors.

Purpose: Stereotactic body radiation therapy (SBRT) has demonstrated clinical benefits for patients with metastatic and/or unresectable cancer. Technical considerations of treatment delivery and nearby organs at risk can limit the use of SBRT in large tumors or those in unfavorable locations. Spatially fractionated radiation therapy (SFRT) may address this limitation because this technique can deliver high-dose radiation to discrete subvolume vertices inside a tumor target while restricting the remainder of the target to a safer lower dose.

Use of the 2D H-C HSQC NMR Methyl Region to Evaluate the Higher Order Structural Integrity of Biopharmaceuticals.

The higher-order structure (HOS) of protein therapeutics is directly related to the function and represents a critical quality attribute. Currently, the HOS of protein therapeutics is characterized by methods with low to medium structural resolution, such as Fourier transform infrared (FTIR), circular dichroism (CD), intrinsic fluorescence spectroscopy (FLD), and differential scanning calorimetry (DSC). High-resolution nuclear magnetic resonance (NMR) methods have now been introduced, representing powerful approaches for HOS characterization (HOS by NMR).

Application programming interface guided QA plan generation and analysis automation.

Purpose: Linear accelerator quality assurance (QA) in radiation therapy is a time consuming but fundamental part of ensuring the performance characteristics of radiation delivering machines. The goal of this work is to develop an automated and standardized QA plan generation and analysis system in the Oncology Information System (OIS) to streamline the QA process.

Methods: Automating the QA process includes two software components: the AutoQA Builder to generate daily, monthly, quarterly, and miscellaneous periodic linear accelerator QA plans within the Treatment Planning System (TPS) and the AutoQA Analysis to analyze images collected on the Electronic Portal Imaging Device (EPID) allowing for a rapid analysis of the acquired QA images.

Technical Note: Self-shielding evaluation and radiation leakage measurement of a jawless ring gantry linac with a beam stopper.

Purpose: To characterize the shielding design and leakage radiation from a newly released ring gantry linac (Halcyon, Varian Medical Systems).

Methods: To assess the radiation leakage surrounding headshield and the radiation level after the beam stopper, measurements were made with GafChromic films. To evaluate the in-room radiation levels, the radiation leakage in the isocenter plane was measured with a large volume spherical ionization chamber (Exradin A6, Standard Imaging).

Technical Note: An alternative approach to verify 6FFF beam dosimetry for Ethos and MR Linac without using a 3D water tank.

Purpose: The current approach to Linac beam dosimetry verification is typically performed utilizing a three-dimensional (3D) water tank system. The 3D beam scanning process is cumbersome, labor intensive, error-prone, and costly. This is especially challenging for the new Ethos system and MR Linacs with a ring gantry.

Dosimetric predictors of symptomatic radiation necrosis after five-fraction radiosurgery for brain metastases.

Background: To identify factors predictive of developing symptomatic radiation necrosis (sRN) among patients with either intact or resected brain metastases undergoing five-fraction stereotactic radiosurgery (5fSRS).

Methods: Multi-institutional retrospective review of 117 brain metastases from 83 patients treated with 5fSRS. The cumulative incidence of sRN and predictors of sRN were calculated using Gray's competing risks and Cox regression.

Internal dose escalation associated with increased local control for melanoma brain metastases treated with stereotactic radiosurgery.

Objective: The internal high-dose volume varies widely for a given prescribed dose during stereotactic radiosurgery (SRS) to treat brain metastases (BMs). This may be altered during treatment planning, and the authors have previously shown that this improves local control (LC) for non-small cell lung cancer BMs without increasing toxicity. Here, they seek to identify potentially actionable dosimetric predictors of LC after SRS for melanoma BM.

Filmless quality assurance of a Leksell Gamma Knife® Icon™.

Purpose: The annual quality assurance (QA) of Leksell Gamma Knife (LGK) systems are typically performed using films. Film is a good candidate for small field dosimetry due to its high spatial resolution and availability. However, there are multiple challenges with using film; film does not provide real-time measurement and requires batch-specific calibration.

Portal dosimetry scripting application programming interface (PDSAPI) for Winston-Lutz test employing ceramic balls.

Purpose: Stereotactic radiosurgery (SRS) and stereotactic body radiation therapy (SBRT) treatments require a high degree of accuracy. Mechanical, imaging, and radiation isocenter coincidence is especially important. As a common method, the Winston-Lutz (WL) test plays an important role.

Implementing a Novel Remote Physician Treatment Coverage Practice for Adaptive Radiation Therapy During the Coronavirus Pandemic.

Purpose: The 2019 coronavirus disease pandemic has placed an increased importance on physical distancing to minimize the risk of transmission in radiation oncology departments. The pandemic has also increased the use of hypofractionated treatment schedules where magnetic resonance-guided online adaptive radiation therapy (ART) can aid in dose escalation. This specialized technique requires increased staffing in close proximity, and thus the need for novel coverage practices to increase physical distancing while still providing specialty care.

Automated and robust beam data validation of a preconfigured ring gantry linear accelerator using a 1D tank with synchronized beam delivery and couch motions.

Purpose: To develop an efficient and automated methodology for beam data validation for a preconfigured ring gantry linear accelerator using scripting and a one-dimensional (1D) tank with automated couch motions.

Materials And Methods: Using an application programming interface, a program was developed to allow the user to choose a set of beam data to validate with measurement. Once selected the program generates a set of instructions for radiation delivery with synchronized couch motions for the linear accelerator in the form of an extensible markup language (XML) file to be delivered on the ring gantry linear accelerator.

Intracranial Stereotactic Radiation Therapy With a Jawless Ring Gantry Linear Accelerator Equipped With New Dual Layer Multileaf Collimator.

Purpose: To test the feasibility of a simplified, robust, workflow for intracranial stereotactic radiation therapy (SRT) using a ring gantry linear accelerator (RGLA) equipped with a dual-layer stacked, staggered, and interdigitating multileaf collimator.

Materials And Methods: Twenty recent clinical SRT cases treated using a radiosurgery c-arm linear accelerator were anonymized. From these data sets, a new planning workflow was developed and used to replan these cases, which then were compared to their clinical counterparts.

Feasibility of proton FLASH irradiation using a synchrocyclotron for preclinical studies.

Purpose: It has been recently shown that radiotherapy at ultrahigh dose rates (>40 Gy/s, FLASH) has a potential advantage in sparing healthy organs compared to that at conventional dose rates. The purpose of this work is to show the feasibility of proton FLASH irradiation using a gantry-mounted synchrocyclotron as a first step toward implementing an experimental setup for preclinical studies.

Methods: A clinical Mevion HYPERSCAN synchrocyclotron was modified to deliver ultrahigh dose rates.

Implementation of a Novel Remote Physician Stereotactic Body Radiation Therapy Coverage Process during the Coronavirus Pandemic.

Purpose: During the coronavirus 2019 disease (COVID-19) pandemic, alternative methods of care are needed to reduce the relative risk of transmission in departments. Also needed is the ability to provide vital radiation oncological care if radiation oncologists (RO) are reallocated to other departments. We implemented a novel remote RO stereotactic body radiation therapy (SBRT) coverage practice, requiring it to be reliable, of high audio and visual quality, timely, and the same level of specialty care as our current in-person treatment coverage practice.