A hybrid radiation detector for simultaneous spatial and temporal dosimetry

In this feasibility study an organic plastic scintillator is calibrated against ionisation chamber measurements and then embedded in a polymer gel dosimeter to obtain a quasi-4D experimental measurement of a radiation field. This hybrid dosimeter was irradiated with a linear accelerator, with temporal measurements of the dose rate being acquired by the scintillator and spatial measurements acquired with the gel dosimeter. The detectors employed in this work are radiologically equivalent; and we show that neither detector perturbs the intensity of the radiation field of the other. By employing these detectors in concert, spatial and temporal variations in the radiation intensity can now be detected and gel dosimeters can be calibrated for absolute dose from a single irradiation

An attempt to determine the saturation dose for PRESAGE

This brief work-in-progress outlines two methods that we have attempted for determining the dose at which the linear relation between optical density of a PRESAGE™ dosimeter and the dose deposited breaks down. Both methods were equally successful in mapping the linear relation up to an optical density of approximately 6.25 cm−1 (absorbance 2..5), but no saturation was found in this region

Optimizing the sensitivity and radiological properties of the PRESAGE® dosimeter using metal compounds

The aim of this study is to investigate the radiation-modifying effects of incorporating commercially available bismuth-, tin- and zinc-based compounds in the composition of the PRESAGEs dosimeter, and the feasibility of employing such compounds for radiation dose enhancement. Furthermore, we demonstrate that metal compounds can be included in the formulation to yield water-equivalent PRESAGEs dosimeters with enhanced dose response. Various concentrations of the metal compounds were added to a newly developed PRESAGEs formulation and the resulting dosimeters were irradiated with 100 kV and 6 MV photon beams. A comparison between sensitivity and radiological properties of the PRESAGEs dosimeters with and without the addition of metal compounds was carried out. Optical density changes of the dosimeters before and after irradiation were measured using a spectrophotometer. In general, when metal compounds were incorporated in the composition of the PRESAGEs dosimeter, the sensitivity of the dosimeters to radiation dose increased depending on the type and concentration of the metal compound, with the bismuth compound showing the highest dose enhancement factor. In addition, these metal compounds were also shown to improve the retention of the post-response absorption value of the PRESAGEs dosimeter over a period of 2 weeks. Thus, incorporating 1-3 mM (ca. 0.2 wt%) of any of the three investigated metal compounds in the composition of the PRESAGEs dosimeter is found to be an efficient way to enhance the sensitivity of the dosimeter to radiation dose and stabilize its post-response for longer times. Furthermore, the addition of small amounts of the metal compounds also accelerates the polymerization of the PRESAGEs dosimeter precursors, significantly reducing the fabrication time. Finally, a novel waterequivalent PRESAGEs dosimeter formula optimized with metal compounds is proposed for clinical use in both kilovoltage and megavoltage radiotherapy dosimetry

Dosimetry of the Amersham 6711 OncoseedTM using PRESAGE TM and optical CT

To investigate the feasibility of solid polymer dosimetry as an accurate 3-D dose verification applied to prostatic brachytherapy, the model 6711 Oncoseed TM was selected for a pilot study comparing experimental methods and Monte Carlo simulations. This study is presented as a typical case study of what can be achieved using solid polymer dosimetry. © 2006 IOP Publishing Ltd

Dosimetry of the Amersham 6711 OncoseedTM using PRESAGE TM and optical CT

To investigate the feasibility of solid polymer dosimetry as an accurate 3-D dose verification applied to prostatic brachytherapy, the model 6711 Oncoseed TM was selected for a pilot study comparing experimental methods and Monte Carlo simulations. This study is presented as a typical case study of what can be achieved using solid polymer dosimetry. © 2006 IOP Publishing Ltd

True-3D scans using PRESAGE^TM and Optical-CT:A case study in proton therapy

MRI and laser-scanned optical-CT are widely reported as being three-dimensional readout methods for gel dosimetry. This preliminary study of proton irradiation of a PRESAGETM transparent solid plastic dosimeter is presented as a case study to illustrate the potential of a true-3D approach. © 2006 IOP Publishing Ltd

Dosimetry of the microSelectron-HDR Ir-192 source using PRESAGE (TM) and optical CT

Optical CT, using a solid polyurethane (PRESAGE (TM)) radiochromic dosimeter, has been used to evaluate dose distributions produced by the microSelectron-HDR Ir-192 source. The anisotropy functions obtained through optical CT are in good agreement with Monte Carlo and previously published results especially at polar angle above 20 degrees. The results indicated an evident potential for using solid polymer dosimetry as an accurate method for 3-D dosimetry, although refinements to the existing methods are necessary before the technique can be used clinically. (C) 2008 Elsevier Ltd. All rights reserved.</p