Treatment of pediatric vaginal rhabdomyosarcoma with the use of a real-time tracked custom applicator.

Purpose: To describe the development, design, and implementation of a 3D printed MR-compatible pediatric vaginal multichannel brachytherapy cylinder. Safety and quality measures to ensure consistent treatment required innovative identification on MR and CT, and real-time tracking.

Methods And Materials: A 4-year-old with vaginal botryoides rhabdomyosarcoma underwent MR-simulation with a custom 3D printed biocompatible resin cylinder with four channels to ensure dose optimization capability.

Seasonal variations in measurements of linear accelerator output.

Purpose: Seasonal trends in linear accelerator output have been reported by at least one institution and data have suggested that they may be present at our center as well. The purpose of this work was to characterize these trends and determine whether local environmental conditions within the treatment rooms may be impacting the linear accelerators and/or the quality control (QC) dosimeter.

Methods: Runtime plots of daily output data, acquired using an in-house ion chamber-based device, over 3 yr and for 15 linear accelerators of different makes and models were reviewed and evaluated.

Precision of 2 Low-dose Abdomen/Pelvis Cone Beam Computed Tomography Protocols for Alignment to Bone and Soft Tissue in Pediatric Patients Receiving Image Guided Radiation Therapy.

Purpose: To evaluate the precision of 2 low-dose cone (LD) beam computed tomography (CBCT) protocols to align to bone and soft tissue for pediatric patients receiving image guided radiation therapy (IGRT) to the abdomen and pelvis.

Methods And Materials: Image-quality evaluation was done for 858 CBCT scans from 46 pediatric patients treated with IGRT from January 2015 to December 2017. The evaluations guided the development of 2 significantly dose-reduced protocols, LD-CBCT1 and a further dose-reduced LD-CBCT2.

Compensator models for fluence field modulated computed tomography.

Purpose: Fluence field modulated computed tomography (FFMCT) presents a novel approach for acquiring CT images, whereby a patient model guides dynamically changing fluence patterns in an attempt to achieve task-based, user-prescribed, regional variations in image quality, while also controlling dose to the patient. This work aims to compare the relative effectiveness of FFMCT applied to different thoracic imaging tasks (routine diagnostic CT, lung cancer screening, and cardiac CT) when the modulator is subject to limiting constraints, such as might be present in realistic implementations.

Methods: An image quality plan was defined for a simulated anthropomorphic chest slice, including regions of high and low image quality, for each of the thoracic imaging tasks.

Fluence field optimization for noise and dose objectives in CT.

Purpose: Selecting the appropriate imaging technique in computed tomography (CT) inherently involves balancing the tradeoff between image quality and imaging dose. Modulation of the x-ray fluence field, laterally across the beam, and independently for each projection, may potentially meet user-prescribed, regional image quality objectives, while reducing radiation to the patient. The proposed approach, called fluence field modulated CT (FFMCT), parallels the approach commonly used in intensity-modulated radiation therapy (IMRT), except "image quality plans" replace the "dose plans" of IMRT.

A local shift-variant Fourier model and experimental validation of circular cone-beam computed tomography artifacts.

Large field of view cone-beam computed tomography (CBCT) is being achieved using circular source and detector trajectories. These circular trajectories are known to collect insufficient data for accurate image reconstruction. Although various descriptions of the missing information exist, the manifestation of this lack of data in reconstructed images is generally nonintuitive.