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A Feasibility Study for the Transit Dosimetry with a Glass Dosimeter in Brachytherapy

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S Moon

S Moon1*, M Yoon1 , W Chung2 , M Chung2 , D Kim2 , (1) Korea University, Seoul, Korea,(2) Kyung Hee University Hospital at Gangdong, Gangdong-gu, Seoul,


SU-F-T-17 (Sunday, July 31, 2016) 3:00 PM - 6:00 PM Room: Exhibit Hall

Purpose: Confirming the dose delivered to a patient is important to make sure the treatment quality and safety of the radiotherapy. Measuring a transit dose of the patient during the radiotherapy could be an interesting way to confirm the patient dose. In this study, we evaluated the feasibility of the transit dosimetry with a glass dosimeter in brachytherapy.

Methods: We made a phantom that inserted the glass dosimeters and placed under patient lying on a couch for cervix cancer brachytherapy. The 18 glass dosimeters were placed in the phantom arranged 6 per row. A point putting 1cm vertically from the source was prescribed as 500.00 cGy. Solid phantoms of 0, 2, 4, 6, 8, 10 cm were placed between the source and the glass dosimeter. The transit dose was measured each thickness using the glass dosimeters and compared with a treatment planning system (TPS).

Results: When the transit dose was smaller than 10 cGy, the average of the differences between measured values and calculated values by TPS was 0.50 cGy and the standard deviation was 0.69 cGy. If the transit dose was smaller than 100 cGy, the average of the error was 1.67 ± 4.01 cGy. The error to a point near the prescription point was -14.02 cGy per 500.00 cGy of the prescription dose.

Conclusion: The distances from the sources to skin of the patient generally are within 10 cm for cervix cancer cases in brachytherapy. The results of this preliminary study showed the probability of the glass dosimeter as the transit dosimeter in brachytherapy.

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