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Title: SU-E-T-606: Performance of MR-Based 3D FXG Dosimetry for Preclinical Irradiation

Abstract

Purpose: Technological advances have revolutionized preclinical radiation research to enable precise radiation delivery in preclinical models. Kilovoltage x-rays and complex geometries in preclinical radiation studies challenge conventional dosimetry methods. Previously developed gel-based dosimetry provides a viable means of accommodating complex geometries and accurately reporting dose at kV energies. This paper will describe the development and evaluation of gel-based ferrous xylenol-orange (FXG) dosimetry using a 7T preclinical imaging system. Methods: To confirm water equivalence, Zeff values were calculated for the FXG material, water and ICRU defined soft tissue. Proton T1 relaxivity response in FXG was measured using a preclinical 7T MR and a small animal irradiator for a dose range of 1–22 Gy. FXG was contained in 50 ml centrifuge tubes and irradiated with a 225 kVp x-ray beam at a nominal dose rate of 2.3 Gy/min. Pre and post irradiation maps of the T1 relaxivity were collected using variable TR spin-echo imaging (TE 6.65 ms; TR 500, 750, 1000, 1500, 2000, 3000 and 5000 ms) with 2 mm thick slices, 0.325 mm/pixel, 3 averages and an acquisition time of 26 minutes. A linear fit to the change in relaxation rate (1/T1) for the delivered doses reported the gel sensitivity inmore » units of ms{sup -1}Gy{sup -1}. Irradiation and imaging studies were repeated using three batches of gel over 72 hrs. Results: FXG has a Zeff of 3.8 for the 225 kVp spectrum used; differing from water and ICRU defined soft tissue by 0.5% and 2.5%, respectively. The average sensitivity for the FXG dosimeter was 31.5 ± 0.7 ms{sup -1}Gy{sup -1} (R{sup 2} = 0.9957) with a y-intercept of −29.4 ± 9.0 ms{sup -1}. Conclusion: Preliminary results for the FXG dosimeter properties, sensitivity, and dose linearity at preclinical energies is promising. Future work will explore anatomically relevant tissue inclusions to test MR performance. Student funding provided by The Terry Fox Foundation Strategic Initiative for Excellence in Radiation Research for the 21st Century at CIHR and the Gifford Ontario Student Opportunity Trust Fund.« less

Authors:
 [1];  [1];  [2];  [2];  [2]
  1. Department of Medical Biophysics, University of Toronto, Toronto, ON (Canada)
  2. (Canada)
Publication Date:
OSTI Identifier:
22496319
Resource Type:
Journal Article
Resource Relation:
Journal Name: Medical Physics; Journal Volume: 42; Journal Issue: 6; Other Information: (c) 2015 American Association of Physicists in Medicine; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
61 RADIATION PROTECTION AND DOSIMETRY; 62 RADIOLOGY AND NUCLEAR MEDICINE; ANIMAL TISSUES; BIOMEDICAL RADIOGRAPHY; CHEMICAL DOSEMETERS; DOSE RATES; DOSIMETRY; GY RANGE 01-10; GY RANGE 10-100; IMAGES; IRRADIATION; IRRADIATION DEVICES; PERFORMANCE; RADIOSENSITIVITY; RADIOTHERAPY; XYLENOL ORANGE

Citation Formats

Welch, M, Jaffray, D, Radiation Medicine Program, Princess Margaret Cancer Centre, Toronto, ON, Department of Radiation Oncology, University of Toronto, Toronto, ON, and TECHNA Institute for the Advancement of Technology for Health, Toronto, ON. SU-E-T-606: Performance of MR-Based 3D FXG Dosimetry for Preclinical Irradiation. United States: N. p., 2015. Web. doi:10.1118/1.4924969.
Welch, M, Jaffray, D, Radiation Medicine Program, Princess Margaret Cancer Centre, Toronto, ON, Department of Radiation Oncology, University of Toronto, Toronto, ON, & TECHNA Institute for the Advancement of Technology for Health, Toronto, ON. SU-E-T-606: Performance of MR-Based 3D FXG Dosimetry for Preclinical Irradiation. United States. doi:10.1118/1.4924969.
Welch, M, Jaffray, D, Radiation Medicine Program, Princess Margaret Cancer Centre, Toronto, ON, Department of Radiation Oncology, University of Toronto, Toronto, ON, and TECHNA Institute for the Advancement of Technology for Health, Toronto, ON. Mon . "SU-E-T-606: Performance of MR-Based 3D FXG Dosimetry for Preclinical Irradiation". United States. doi:10.1118/1.4924969.
@article{osti_22496319,
title = {SU-E-T-606: Performance of MR-Based 3D FXG Dosimetry for Preclinical Irradiation},
author = {Welch, M and Jaffray, D and Radiation Medicine Program, Princess Margaret Cancer Centre, Toronto, ON and Department of Radiation Oncology, University of Toronto, Toronto, ON and TECHNA Institute for the Advancement of Technology for Health, Toronto, ON},
abstractNote = {Purpose: Technological advances have revolutionized preclinical radiation research to enable precise radiation delivery in preclinical models. Kilovoltage x-rays and complex geometries in preclinical radiation studies challenge conventional dosimetry methods. Previously developed gel-based dosimetry provides a viable means of accommodating complex geometries and accurately reporting dose at kV energies. This paper will describe the development and evaluation of gel-based ferrous xylenol-orange (FXG) dosimetry using a 7T preclinical imaging system. Methods: To confirm water equivalence, Zeff values were calculated for the FXG material, water and ICRU defined soft tissue. Proton T1 relaxivity response in FXG was measured using a preclinical 7T MR and a small animal irradiator for a dose range of 1–22 Gy. FXG was contained in 50 ml centrifuge tubes and irradiated with a 225 kVp x-ray beam at a nominal dose rate of 2.3 Gy/min. Pre and post irradiation maps of the T1 relaxivity were collected using variable TR spin-echo imaging (TE 6.65 ms; TR 500, 750, 1000, 1500, 2000, 3000 and 5000 ms) with 2 mm thick slices, 0.325 mm/pixel, 3 averages and an acquisition time of 26 minutes. A linear fit to the change in relaxation rate (1/T1) for the delivered doses reported the gel sensitivity in units of ms{sup -1}Gy{sup -1}. Irradiation and imaging studies were repeated using three batches of gel over 72 hrs. Results: FXG has a Zeff of 3.8 for the 225 kVp spectrum used; differing from water and ICRU defined soft tissue by 0.5% and 2.5%, respectively. The average sensitivity for the FXG dosimeter was 31.5 ± 0.7 ms{sup -1}Gy{sup -1} (R{sup 2} = 0.9957) with a y-intercept of −29.4 ± 9.0 ms{sup -1}. Conclusion: Preliminary results for the FXG dosimeter properties, sensitivity, and dose linearity at preclinical energies is promising. Future work will explore anatomically relevant tissue inclusions to test MR performance. Student funding provided by The Terry Fox Foundation Strategic Initiative for Excellence in Radiation Research for the 21st Century at CIHR and the Gifford Ontario Student Opportunity Trust Fund.},
doi = {10.1118/1.4924969},
journal = {Medical Physics},
number = 6,
volume = 42,
place = {United States},
year = {Mon Jun 15 00:00:00 EDT 2015},
month = {Mon Jun 15 00:00:00 EDT 2015}
}