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| Comparison Research on Three International Dosimetry Code in 60Co γ-ray Beams |
| CHENG Jin-sheng1, Lu Ji-long2, LIU Ya1, LIU Li-ming1, GUO Zhao-hui1 |
1. National Institute for Radiological Protection, China CDC, Beijing 100088 China;
2. General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China |
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Abstract Objective The code of practice for radiotherapy dosimetry in our country is not directly based on standards of absorbed dose to water, but based on exposure standards or air kerma standards firstly, and then transform the measurement into absorbed dose by adopting various modifying factors through dosimetry code involved. This essay will probe into the error caused by different codes of practice for radiotherapy dosimetry in terms of absorbed dose. Methods In this research, we adopt three radiotherapy dosimetry codes including ICRU23, IAEA TRS277 and IAEA TRS398, by which different types of chambers measure the absorbed dose to water respectively in 60Co γ ray beams under same condition. We analyze the divergence produced by the three codes mentioned above. Results Having measured the absorbed dose to water through 10 six types of chambers under the same condition of 60Co γ ray beams, we find that three codes in question produce divergences, which are within 2% respectively. Meanwhile, there is certain dispersal among different types of chambers as well. Conclusion Different measurements of radiotherapy dosimetry codes will produce bigger divergences. To reduce inaccuracy in modern radiation therapy in our nation, we should establish the calibration system of measuring absorbed doses to water as soon as possible.
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Received: 12 May 2016
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