Investigation of radiological properties and water equivalency of PRESAGE ® dosimeters

Abstract. In a high resolution image-guided small animal irradiation platform, a cone beam computed tomography (CBCT) is integrated with an irradiation unit for precise targeting. Precise quality assurance is essential for both imaging and irradiation components. The conventional commissioning techniques with films face major challenges due to alignment uncertainty and labour intensive film preparation and scanning. In addition, due to the novel design of this platform the mouse stage rotation for CBCT imaging is perpendicular to the gantry rotation for irradiation. Because these two rotations are associated with different mechanical systems, discrepancy between rotation isocenters exists. In order to deliver x-ray precisely, it is essential to verify coincidence of the imaging and the irradiation isocenters. A 3-D PRESAGE dosimeter can provide an excellent tool for checking dosimetry and verifying coincidence of irradiation and imaging coordinates in one system. Dosimetric measurements were performed to obtain beam profiles and percent depth dose (PDD). Isocentricity and coincidence of the mouse stage and gantry rotations were evaluated with starshots acquired using PRESAGE dosimeters. A single PRESAGE dosimeter can provide 3-D information in both geometric and dosimetric uncertainty, which is crucial for translational studies.

Section: Methodsmentioning

confidence: 99%

“…In this study three dosimetric tools were employed: a farmer type ionization chamber (N30013, PTW), radiochromic EBT2 films, and PRESAGE 3-D [3] dosimeters with optical CT scanner (OCTOPUS, MGS Inc.). The ion-chamber was used to obtain absolute dose rates.…”

Section: Introductionmentioning

confidence: 99%

A small animal image guided irradiation system study using 3D dosimeters

Qian

Admovics

2015

“…Both polymer gels [4] and PRESAGE [5,6] radiochromic plastic dosimeter, in conjunction with optical CT scanner [7,8], have been employed to verify 3-D dose distribution for complex treatments with photon beams, such as IMRT and stereotactic radiosurgery [9,10]. These studies have shown promising results in providing a 3-D dosimetry tools for photon external beam treatments.…”

Section: Introductionmentioning

confidence: 99%

“…Detailed three-dimensional dosimetric information for a proton beam is crucial for accurate treatment planning design and treatment delivery due to the sharp dose falloff at the end of the beam range and laterally at the field edges [1][2][3]. It is more challenging to measure the 3-D dose distribution of a pencil beam (1 -1.5 cm diameter) because of its small field size as well as the complexity of dose changes in various directions.Both polymer gels [4] and PRESAGE [5,6] radiochromic plastic dosimeter, in conjunction with optical CT scanner [7,8], have been employed to verify 3-D dose distribution for complex treatments with photon beams, such as IMRT and stereotactic radiosurgery [9,10]. These studies have shown promising results in providing a 3-D dosimetry tools for photon external beam treatments.…”

mentioning

confidence: 99%

Dosimetric assessment of the PRESAGE dosimeter for a proton pencil beam

Qian

Adamovics

et al. 2013

Abstract. The objective of this study is to assess the feasibility of using PRESAGE dosimeters for proton pencil beam dosimetry. Two different formulations of phantom materials were tested for their suitability in characterizing a single proton pencil beam. The dosimetric response of PRESAGE was found to be linear up to 4Gy. First-generation optical CT scanner, OCTOPUS TM was used to implement dose distributions for proton pencil beams since it provides most accurate readout. Percentage depth dose curves and beam profiles for two proton energy, 110 MeV, and 93 MeV, were used to evaluate the dosimetric performance of two PRESAGE phantom formulas. The findings from this study show that the dosimetric properties of the phantom materials match with basic physics of proton beams. IntroductionA proton beam has the advantage in its characteristic distribution of dose with depth. The depth dose peaks to highest value near the end of its range followed by a rapid falloff to zero. These physical characteristics of proton beams offer higher dose conformity to the tumor and lower dose to the surrounding normal tissues than a photon beam can achieve. There are two beam delivery systems in terms of beam spreading to its desired field cross section: 1) passive beam spreading by thin sheets of high-atomic materials; or 2) pencil beam scanning by magnets. Proton pencil beam scanning can provide precise and efficient treatment delivery for both conventional and intensity modulated proton therapy (IMPT) techniques. Detailed three-dimensional dosimetric information for a proton beam is crucial for accurate treatment planning design and treatment delivery due to the sharp dose falloff at the end of the beam range and laterally at the field edges [1][2][3]. It is more challenging to measure the 3-D dose distribution of a pencil beam (1 -1.5 cm diameter) because of its small field size as well as the complexity of dose changes in various directions.Both polymer gels [4] and PRESAGE [5,6] radiochromic plastic dosimeter, in conjunction with optical CT scanner [7,8], have been employed to verify 3-D dose distribution for complex treatments with photon beams, such as IMRT and stereotactic radiosurgery [9,10]. These studies have shown promising results in providing a 3-D dosimetry tools for photon external beam treatments. There are some recent studies on proton dosimetry using polymer gels [11] and PRESAGE dosimeters [12], with optical CT scanners as readout systems. However, there has not been any report on dosimetry of a

“…® is an exceptional 3D radiochromic dosimeter with unique characteristics that are desirable for clinical applications [1][2][3][4]. Unlike polymer gel dosimeters, PRESAGE ® is composed of an optically clear polyurethane matrix that can be fabricated into any shape and requires no supporting container, a reporting system comprising of leucomalachite green (LMG) dye or one of its derivatives [5], and a halocarbon compound as a radical source [6,7].…”

Section: Introduction Presagementioning

confidence: 99%

An investigation into the potential influence of oxygen on the efficiency of the PRESAGE^®dosimeter

Alqathami

Blencowe

Ibbott

2015

Abstract. The influence of atmospheric oxygen on the efficiency of the PRESAGE ® dosimeter was investigated. Batches of PRESAGE ® and reporting system solution were deoxygenated using nitrogen and compared to similar batches that were exposed to atmospheric oxygen during fabrication. The overall results show little influence of oxygen on the characteristics of PRESAGE ® with the radical initiator oxidizing the leucomalachite green in the presence of oxygen. However, when deoxygenating the reporting system the sensitivity to radiation dose increased by 30% compared to the non-deoxygenated system. A slight improvement in sensitivity (5%) was achieved by deoxygenating the PRESAGE ® precursors prior to casting. The results suggest that the solid polyurethane matrix is not permeable to atmospheric oxygen. In addition, there were no observed changes in the dose linearity, absorption spectrum and post-response photofading characteristics of PRESAGE ® under the conditions investigated.