Prog Med Phys.  2020 Jun;31(2):20-28. 10.14316/pmp.2020.31.2.20.

Postal Dosimetry Audits for the Domestic Medical Linear Accelerator

• Kim KB
• Choi SH

• KMID: 2503939
• DOI: http://doi.org/10.14316/pmp.2020.31.2.20

Abstract

Purpose
The objective of this study is to perform Postal dosimetry audits for medical linear accelerators in radiation therapy institutions using glass dosimeters and Gafchromic film reading systems and postal dosimetry audit procedures, and to evaluate radiation therapy doses and mechanical accuracy in medical institutions.
Methods
Photon output measured and analyzed using a standard phantom for measuring photon output dose using a glass dosimeter for medical linear accelerators. Mechanical accuracy was measured and analyzed using software for film measurement.
Results
Measurement and analysis of photon beam output dose using a standard phantom glass dosimeter for photon beam output dose measurement was completed. All tolerance doses were within 5%. Mechanical accuracy measurement and analysis using a standard phantom for verifying the mechanical accuracy of linear accelerator (LINAC) using a Gafchromic film were completed, and all results were shown within tolerances (2 mm or less).
Conclusions
In this study, Postal dosimetry audits were performed on the output dose and mechanical accuracy of photon beams (207 beams) for 106 LINACs from 48 institutions. As a result of corrective action and re-execution, it was confirmed that all engines met the acceptable standard within 2 mm in the linear accelerator.

Keyword

Postal dosimetry audit; Linear accelerator; Glass dosimeter; Gafchromic film

Figure

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  Fig. 1 Fabrication of phantom for measuring output dose using a glass dosimeter.

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  Fig. 2 Phantom for measuring mechanical accuracy.

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  Fig. 3 Output dose result for 4, 6, 10, 15 MV of linear accelerator.

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  Fig. 4 Evaluation results for field size of linear accelerator.

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  Fig. 5 Evaluation results of rotation center axis for couch, colli­mator, and gantry.

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  Fig. 6 Statistics of output dose evaluation by energy. LINAC, linear accelerator.

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  Fig. 7 Mechanical accuracy evaluation results. LINAC, linear accelerator.

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  Fig. 8 Lead time conducted for postal dosimetry audit for all medical institutions.

Reference

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