Verification of patient-specific dose distributions in proton therapy using a commercial two-dimensional ion chamber array
- Department of Radiation Physics, University of Texas MD Anderson Cancer Center, Houston, Texas 77030 (United States)
Purpose: The purpose of this study was to determine whether a two-dimensional (2D) ion chamber array detector quickly and accurately measures patient-specific dose distributions in treatment with passively scattered and spot scanning proton beams. Methods: The 2D ion chamber array detector MatriXX was used to measure the dose distributions in plastic water phantom from passively scattered and spot scanning proton beam fields planned for patient treatment. Planar dose distributions were measured using MatriXX, and the distributions were compared to those calculated using a treatment-planning system. The dose distributions generated by the treatment-planning system and a film dosimetry system were similarly compared. Results: For passively scattered proton beams, the gamma index for the dose-distribution comparison for treatment fields for three patients with prostate cancer and for one patient with lung cancer was less than 1.0 for 99% and 100% of pixels for a 3% dose tolerance and 3 mm distance-to-dose agreement, respectively. For spot scanning beams, the mean ({+-} standard deviation) percentages of pixels with gamma indices meeting the passing criteria were 97.1%{+-}1.4% and 98.8%{+-}1.4% for MatriXX and film dosimetry, respectively, for 20 fields used to treat patients with prostate cancer. Conclusions: Unlike film dosimetry, MatriXX provides not only 2D dose-distribution information but also absolute dosimetry in fractions of minutes with acceptable accuracy. The results of this study indicate that MatriXX can be used to verify patient-field specific dose distributions in proton therapy.
- OSTI ID:
- 22096816
- Journal Information:
- Medical Physics, Vol. 37, Issue 11; Other Information: (c) 2010 American Association of Physicists in Medicine; Country of input: International Atomic Energy Agency (IAEA); ISSN 0094-2405
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
61 RADIATION PROTECTION AND DOSIMETRY
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY
60 APPLIED LIFE SCIENCES
ACCURACY
COMPARATIVE EVALUATIONS
FILM DOSIMETRY
IONIZATION CHAMBERS
LUNGS
NEOPLASMS
PATIENTS
PHANTOMS
PLANNING
PROSTATE
PROTON BEAMS
RADIATION DOSE DISTRIBUTIONS
RADIATION DOSES
RADIOTHERAPY
VERIFICATION
WATER