Clinical Radiation Physics Service

Division Of Clinical Sciences - Nci

Investigators

Linked publications, trials & patents

Abstract

We have a series of initiatives utilizing our High Dose-Rate Remote Afterloader (HDR) using a small, high intensity 192Ir source for interstitial and intercavitary brachytherapy. The department now has two state-of-the-art Varian TrueBeam STX accelerators which are equipped with 120-leaf high-definition multi-leaf collimators with leaf widths as thin as 2.5 mm. This renders them capable of performing frameless stereotactic radiosurgery (SRS), although a set of circular collimators with diameters ranging from 4mm to 25mm and an SRS planning module are included in the acquisition. The patient couches also allow for 6 Degrees-of-Freedom (6DOF) to greatly improve positional accuracy by permitting corrections for pitch, roll and yaw, in addition to the traditional longitudinal, lateral and vertical position adjustments. The treatment delivery parameters of these two accelerators are matched to within 0.5%, thus providing true redundancy, assuring that patients can continue to receive their treatments according to their fractionation schedule. These machines include the Edge Extracranial SABR Package that will permit them to deliver frameless stereotactic body radiation therapy (SBRT) using advanced motion management based on radiofrequency local positioning using implanted fiducial transponders and infrared cameras. The revised Edge package includes a Calypso radiofrequency positioning system, utilizing implantable fiducial transducers and real-time tracking capability. The real-time optical tracking utilizes an upgraded Optical Surface Monitoring System (VisionRT) system to monitor the body surface and to interrupt the treatment if the surface distorts (due to motion) and the clinical implementation of a prostate radiotherapy protocol using Calypso RF transponders to monitor prostate position and correspondingly gate the treatment delivery. ROB has acquired three Varian VCD Visual Coaching Devices (1 for each accelerator and 1 for the CT-simulator), have installed and are currently using them clinically to improve motion management during radiation therapy. ROB continues to use our Elekta Flexitron 40 channel High-Dose-Rate (HDR) remote brachytherapy afterloader for prostate brachytherapy and has upgraded the associated prostate brachytherapy planning system, which is Windows 11 compliant. This is used in conjunction with our B-K ultrasound unit, which has vastly improved imaging capabilities relative to the previous unit. We have acquired a couch-mounted stepper-stabilizer to improve needle insertion methodology and are working on adapting a motorized scanning system for the probe to speed image acquisition. ROB is beginning its transition to ARIA-RO version 18. This now utilizes the NIH Active Directory system, which improves security, and utilizes a virtual server environment to enhance operational reliability. ROB has successfully transitioned to a new IT backbone, streamlining communication between ARIA and Eclipse workstations and TrueBeam accelerators at the Bethesda campus and the virtual server farm located at the NCI Shady Grove Data center. This provides for stable communications. ROB has also upgraded its Machine Shop to conform with current electrical standards as well as permitting the installation of more advanced fabrication equipment, such as a 3-D printer and an advanced water jet cutter, which is vastly more capable than the previous model, to better support clinical research projects.