Display options
Cite
Rodrigues A, Nguyen G, Li Y, et al. SU-E-T-275: Dose Verification in a Small Animal Image-Guided Radiation Therapy X-Ray Machine: A Dose Comparison between TG-61 Based Look-Up Table and MOSFET Method for Various Collimator Sizes. Med Phys. 2012;39(6):3766doi: 10.1118/1.4735343.
Rodrigues, A., Nguyen, G., Li, Y., Roy Choudhury, K., Kirsch, D., Das, S., & Yoshizumi, T. (2012). SU-E-T-275: Dose Verification in a Small Animal Image-Guided Radiation Therapy X-Ray Machine: A Dose Comparison between TG-61 Based Look-Up Table and MOSFET Method for Various Collimator Sizes. Medical physics, 39(6), 3766. https://doi.org/10.1118/1.4735343
Rodrigues, A, et al. "SU-E-T-275: Dose Verification in a Small Animal Image-Guided Radiation Therapy X-Ray Machine: A Dose Comparison between TG-61 Based Look-Up Table and MOSFET Method for Various Collimator Sizes." Medical physics vol. 39,6 (2012): 3766. doi: https://doi.org/10.1118/1.4735343
Rodrigues A, Nguyen G, Li Y, Roy Choudhury K, Kirsch D, Das S, Yoshizumi T. SU-E-T-275: Dose Verification in a Small Animal Image-Guided Radiation Therapy X-Ray Machine: A Dose Comparison between TG-61 Based Look-Up Table and MOSFET Method for Various Collimator Sizes. Med Phys. 2012 Jun;39(6):3766. doi: 10.1118/1.4735343. PMID: 28517298.
Copy Download .nbib Format: NLM
Share it on

Med Phys. 2012 Jun;39(6):3766. doi: 10.1118/1.4735343.

SU-E-T-275: Dose Verification in a Small Animal Image-Guided Radiation Therapy X-Ray Machine: A Dose Comparison between TG-61 Based Look-Up Table and MOSFET Method for Various Collimator Sizes.

Medical physics

A Rodrigues, G Nguyen, Y Li, K Roy Choudhury, D Kirsch, S Das, T Yoshizumi

Affiliations

  1. Duke University, Durham, NC.
  2. Duke University Medical Center, Durham, NC.

PMID: 28517298 DOI: 10.1118/1.4735343

Abstract

PURPOSE: To verify the accuracy of TG-61 based dosimetry with MOSFET technology using a tissue-equivalent mouse phantom.

METHODS: Accuracy of mouse dose between a TG-61 based look-up table was verified with MOSFET technology. The look-up table followed a TG-61 based commissioning and used a solid water block and radiochromic film. A tissue-equivalent mouse phantom (2 cm diameter, 8 cm length) was used for the MOSFET method. Detectors were placed in the phantom at the head and center of the body. MOSFETs were calibrated in air with an ion chamber and f-factor was applied to derive the dose to tissue. In CBCT mode, the phantom was positioned such that the system isocenter coincided with the center of the MOSFET with the active volume perpendicular to the beam. The absorbed dose was measured three times for seven different collimators, respectively. The exposure parameters were 225 kVp, 13 mA, and an exposure time of 20 s.

RESULTS: For a 10 mm, 15 mm, and 20 mm circular collimator, the dose measured by the phantom was 4.3%, 2.7%, and 6% lower than TG-61 based measurements, respectively. For a 10 × 10 mm, 20 × 20 mm, and 40 × 40 mm collimator, the dose difference was 4.7%, 7.7%, and 2.9%, respectively.

CONCLUSIONS: The MOSFET data was systematically lower than the commissioning data. The dose difference is due to the increased scatter radiation in the solid water block versus the dimension of the mouse phantom leading to an overestimation of the actual dose in the solid water block. The MOSFET method with the use of a tissue- equivalent mouse phantom provides less labor intensive geometry-specific dosimetry and accuracy with better dose tolerances of up to ± 2.7%.

© 2012 American Association of Physicists in Medicine.

Keywords: Collimators; Cone beam computed tomography; Dosimetry; Ionization chambers; MOSFETs; Medical imaging; Radiation therapy; Time measurement; Tissues

Publication Types