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| TLD Quality Audit Method for Intensity Modulated Radiotherapy in the Presence of Heterogeneities |
| HE Zhi-jian1, LUO Su-ming1, WU Hao2, HU Chuan-peng3, LIU Ran4, WANG Jin5, LIU Bao-chen6 |
1. National Institute for Radiological Protection, Chinese Center for Disease Control and Prevention, Beijing 100088 China;
2. Beijing Cancer Hospital;
3. Henan Institnte of Occupational Medicine;
4. Sichuan Center for Disease Control and Prevention;
5. Jiangsu Center for Disease Control and Prevertion;
6. Liaoning Center for Disease Control and Prevention |
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Abstract Objective To check the heterogeneity corrected dose calculations performed by the treatment planning system.Methods Homogeneous polystyrene solid phantom with TLD,Polystyrene/lung solid phantom with TLD and Polystyrene/bone solid phantom with TLD will be required to be CT scanned respectively,images exported to the TPS and monitor units calculated as if to deliver 2Gy to the TLD on photon beam axis.The TLDs was irradiated by high energy X-ray. TLDs irradiated by measuring and dose calculation,and D(TLD)/D(TPS) dose ratio in 0.95 to 1.05 was acceptable.Results Verificationresults showed that homogeneous polystyrene solid phantom on axis (P) dose and polystyrene/bone solid phantom on axis (BP) dose are good,polystyrene/lung solid phantom on axis (LP) and off-axis (LL) relative deviation are large.Conclusion Heterogeneity of photon beam dose correction is very important in radiotherapy,especially in the lung tissue. Improper correction,the deviation for lung tissue can also be reached 11.1%,off-axis cases up to 18.4%.The deviation for bone tissue is smaller.
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Received: 25 April 2016
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