Prog Med Phys.  2013 Jun;24(2):92-98.

Reading Deviations of Glass Rod Dosimeters Using Different Pre-processing Methods for Radiotherapeutic in-vivo Dosimetry

• Jeon H
• Nam J
• Park D
• Kim YH
• Kim W
• Kim D
• Ki Y
• Kim D
• Lee JH

Abstract

The experimental verification of treatment planning on the treatment spot is the ultimate method to assure quality of radiotherapy, so in-vivo skin dose measurement is the essential procedure to confirm treatment dose. In this study, glass rod dosimeter (GRD), which is a kind of photo-luminescent based dosimeters, was studied to produce a guideline to use GRDs in vivo dosimetry for quality assurance of radiotherapy. The pre-processing procedure is essential to use GRDs. This is a heating operation for stabilization. Two kinds of pre-processing methods are recommended by manufacturer: a heating method (70 degree, 30 minutes) and a waiting method (room temperature, 24 hours). We equally irradiated 1.0 Gy to 20 GRD elements, and then different pre-processing were performed to 10 GRDs each. In heating method, reading deviation of GRDs at same time were relatively high, but the deviation was very low as time went on. In waiting method, the deviation among GRDs was low, but the deviation was relatively high as time went on. The meaningful difference was found between mean reading values of two pre-processing methods. Both methods present mean dose deviation under 5%, but the relatively high effect by reading time was observed in waiting method. Finally, GRD is best to perform in-vivo dosimetry in the viewpoint of accuracy and efficiency, and the understanding of how pre-processing affect the accuracy is asked to perform most accurate in-vivo dosimetry. The further study is asked to acquire more stable accuracy in spite of different irradiation conditions for GRD usage.

Keyword

Treatment dose verification; Glass rod dosimeter; Pre-processing method

MeSH Terms

Glass
Heating
Hot Temperature
Skin

Figure

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  Fig. 1. (a) The dose measurement procedure, (b) a GRD element, (c) a GRD reader, and (d) inner structure of the reader.

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  Fig. 2. (a) Experimental setup of GRD elements and an ion chamber for radiation exposure and (b) its actual figure.

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  Fig. 3. Mean reading deviations of GRDs according to time delay between pre-processing and reading.

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  Fig. 4. The histogram of in-vivo dose readings with the heating method.

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  Fig. 5. The histogram of in-vivo dose readings with the waiting method.

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