AAPM Task Group 334: A guidance document to using radiotherapy immobilization devices and accessories in an MR environment.

Use of magnetic resonance (MR) imaging in radiation therapy has increased substantially in recent years as more radiotherapy centers are having MR simulators installed, requesting more time on clinical diagnostic MR systems, or even treating with combination MR linear accelerator (MR-linac) systems. With this increased use, to ensure the most accurate integration of images into radiotherapy (RT), RT immobilization devices and accessories must be able to be used safely in the MR environment and produce minimal perturbations. The determination of the safety profile and considerations often falls to the medical physicist or other support staff members who at a minimum should be a Level 2 personnel as per the ACR.

Dosimetric and planning efficiency comparison for lung SBRT: CyberKnife vs VMAT vs knowledge-based VMAT.

This is the first study that compared treatment plan quality and planning efficiency for lung stereotactic body radiation therapy (SBRT) using CyberKnife (CK) Multiplan vs Varian Eclipse treatment planning systems, including volumetric modulated arc therapy (VMAT) and knowledge-based VMAT (KBP-VMAT). Thirteen lung SBRT patients treated with 50 to 55 Gy in 3 or 5 fractions were retrospectively included in this study. CK plans created with Multiplan V.

A Monte Carlo model for organ dose reconstruction of patients in pencil beam scanning (PBS) proton therapy for epidemiologic studies of late effects.

Significant efforts such as the Pediatric Proton/Photon Consortium Registry (PPCR) involving multiple proton therapy centers have been made to conduct collaborative studies evaluating outcomes following proton therapy. As a groundwork dosimetry effort for the late effect investigation, we developed a Monte Carlo (MC) model of proton pencil beam scanning (PBS) to estimate organ/tissue doses of pediatric patients at the Maryland Proton Treatment Center (MPTC), one of the proton centers involved in the PPCR. The MC beam modeling was performed using the TOPAS (TOol for PArticle Simulation) MC code and commissioned to match measurement data within 1% for range, and 0.

Efficient Interplay Effect Mitigation for Proton Pencil Beam Scanning by Spot-Adapted Layered Repainting Evenly Spread out Over the Full Breathing Cycle.

Purpose: To develop and implement a practical repainting method for efficient interplay effect mitigation in proton pencil beam scanning (PBS).

Methods And Materials: A new flexible repainting scheme with spot-adapted numbers of repainting evenly spread out over the whole breathing cycle (assumed to be 4 seconds) was developed. Twelve fields from 5 thoracic and upper abdominal PBS plans were delivered 3 times using the new repainting scheme to an ion chamber array on a motion stage.

A comparison of two pencil beam scanning treatment planning systems for proton therapy.

Objective: Analytical dose calculation algorithms for Eclipse and Raystation treatment planning systems (TPS), as well as a Raystation Monte Carlo model are compared to corresponding measured point doses.

Method: The TPS were modeled with the same beam data acquired during commissioning. Thirty-five typical plans were made with each planning system, 31 without range shifter and four with a 5 cm range shifter.

Comparison of multi-institutional Varian ProBeam pencil beam scanning proton beam commissioning data.

Purpose: Commissioning beam data for proton spot scanning beams are compared for the first two Varian ProBeam sites in the United States, at the Maryland Proton Treatment Center (MPTC) and Scripps Proton Therapy Center (SPTC). In addition, the extent to which beams can be matched between gantry rooms at MPTC is investigated.

Method: Beam data for the two sites were acquired with independent dosimetry systems and compared.

3D tumor tissue analogs and their orthotopic implants for understanding tumor-targeting of microenvironment-responsive nanosized chemotherapy and radiation.

Unlabelled: An appropriate representation of the tumor microenvironment in tumor models can have a pronounced impact on directing combinatorial treatment strategies and cancer nanotherapeutics. The present study develops a novel 3D co-culture spheroid model (3D TNBC) incorporating tumor cells, endothelial cells and fibroblasts as color-coded murine tumor tissue analogs (TTA) to better represent the tumor milieu of triple negative breast cancer in vitro. Implantation of TTA orthotopically in nude mice, resulted in enhanced growth and aggressive metastasis to ectopic sites.

A feasibility study using TomoDirect for craniospinal irradiation.

The feasibility of delivering craniospinal irradiation (CSI) with TomoDirect is investigated. A method is proposed to generate TomoDirect plans using standard three-dimensional (3D) beam arrangements on Tomotherapy with junctioning of these fields to minimize hot or cold spots at the cranial/spinal junction. These plans are evaluated and compared to a helical Tomotherapy and a three-dimensional conformal therapy (3D CRT) plan delivered on a conventional linear accelerator (linac) for CSI.

Quantification of artifact reduction with real-time cine four-dimensional computed tomography acquisition methods.

Purpose: To quantify the magnitude and frequency of artifacts in simulated four-dimensional computed tomography (4D CT) images using three real-time acquisition methods- direction-dependent displacement acquisition, simultaneous displacement and phase acquisition, and simultaneous displacement and velocity acquisition- and to compare these methods with commonly used retrospective phase sorting.

Methods And Materials: Image acquisition for the four 4D CT methods was simulated with different displacement and velocity tolerances for spheres with radii of 0.5 cm, 1.

Retrospective analysis of artifacts in four-dimensional CT images of 50 abdominal and thoracic radiotherapy patients.

Purpose: To quantify the type, frequency, and magnitude of artifacts in four-dimensional (4D) CT images acquired using a multislice cine method.

Methods And Materials: Fifty consecutive patients who underwent 4D-CT scanning and radiotherapy for thoracic or abdominal cancers were included in this study. All the 4D-CT scans were performed on the GE multislice PET/CT scanner with the Varian Real-time Position Management system in cine mode.