A promising new prostate dosimetry system has been developed for clinical radiation therapy. coupled device (CCD video camera) monitoring system and the manufacturer’s integrated software package. The PSD probes were irradiated at 6 MV in a Solid Water? phantom. Irradiations were performed having a 6 MV linear accelerator using anterior-posterior/posterior-anterior (AP/PA) matched fields to a maximum dose of 200 cGy inside a 100 cm source-axis range (SAD geometry. As a whole the OARtrac system has good accuracy with a imply error of 0.01% and an error spread of ± 5.4% in the 95% confidence interval. These results reflect the PSD probes’ accuracy before their final insertion into endorectal balloons. Long term work will test the dosimetric effects of mounting the PSD probes within the endorectal balloon assemblies. 1 Introduction External beam radiotherapy for the prostate must be cautiously planned and delivered to provide the required dose to the prospective organ while sparing the radio-sensitive bladder and rectal constructions. Achieving these goals often requires a razor-sharp dose gradient in the rectoprostatic interface. Sudden anatomic changes such as the build up of colorectal gas or patient movement can result in dose deviations in Dimesna (BNP7787) the rectal wall (de Crevoisier dosimetry combined with a prostate immobilization device such as an endorectal balloon potentially offers a means of simultaneously mitigating the effects of prostate motion and monitoring true anterior wall rectal dose (Hardcastle scintillation dosimetry system designed to measure rectal wall dose during prostate radiotherapy methods. In its total form the OARtrac? system consists of four main parts: 1) a disposable endorectal balloon assembly inlayed with two self-employed plastic scintillation radiation detectors that together with a duplex fiber-optical connector constitute a PSD probe assembly; 2) a permanently routed dietary fiber optical cable that transmits detector signals out of the treatment vault; 3) an optics package having a charge coupled device (CCD video camera) that actions the scintillator output signal (number 1); Dimesna (BNP7787) and 4) a personal computer-based software readout system located in the control space of the linear accelerator treatment machine. (OARtrac is meant to Dimesna (BNP7787) stand for Organ At Risk tracking). Number 1 OARtrac optics package comprising the optics and CCD video camera. This unit is normally placed within the treatment vault control space along with the analysis computer. A long dietary fiber optic cable is definitely permanently routed through the treatment vault walls linking … The plastic scintillation detector (PSD) probes are individually calibrated from the University of Texas MD Dimesna (BNP7787) Anderson Dosimetry Laboratory (MDADL). Each PSD probe is definitely labeled with barcoded calibration factors to allow both internal PSD’s calibration factors to be transferred simply to the monitoring software system. Each PSD probe will become sealed within an endorectal balloon post calibration and will be sold in pre-calibrated plenty to medical users. Clinical users will monitor the PSD probes during radiation treatments through their permanently installed CCD video camera systems mounted within their accelerator vault control rooms. The OARtrac system is novel in that it is a scintillation dosimetry system with interchangeable and disposable pre-calibrated detector cables. Disposable PSD probe assemblies allow for easy and sanitary medical use. To our knowledge no scintillation detector systems like this have been discussed in the literature. This study measures the accuracy and precision of the end-to-end detector system prior to the final manufacturing step Dimesna (BNP7787) of mounting the endorectal balloon assemblies onto the PSD probes. 2 Methods and Materials The PSD probes GTF2H used for this study were produced by RadiaDyne as part of the OARtrac dosimetry system and consist of two side by side PSDs much like those used in the study by Wootton et al 2014 Each individual PSD consists of a plastic scintillating dietary fiber optically coupled to a definite optical dietary fiber both of which are encased in an opaque flexible plastic jacketing. The plastic scintillating dietary fiber was 2 mm long and 1 mm in diameter resulting in an active detector volume of 0.00157 cm3. A duplex optical connector was placed at the end of each probe to allow for convenient use and consistent transmission of scintillation light from the two PSDs to a CCD video camera for quantification. The two.