Prog Med Phys.  2016 Dec;27(4):224-231. 10.14316/pmp.2016.27.4.224.

Comparison of Temperature Distribution in Agar Phantom and Gel Bolus Phantom by Radiofrequency Hyperthermia

• Jung DK
• Kim SK
• Lee JH
• Youn SM
• Kim HD
• Oh SA
• Park JW
• Yea JW

• KMID: 2376556
• DOI: http://doi.org/10.14316/pmp.2016.27.4.224

Abstract

The usefulness of Gel Bolus phantom was investigated by comparing the temperature distribution characteristic of the agar phantom produced to investigate the dose distribution characteristic of radiofrequency hyperthermia device with that of the Gel Bolus phantom under conditions similar to those of an agar phantom that can continuously carry out temperature measurement. The temperatures of the agar phantom and the Gel Bolus phantom were raised to 36.5±3℃ and a temperature sensing was inserted at depths of 5, 10, and 15 cm from the phantom central axis. The temperature increase rate and the coefficient of determination were analyzed while applying output powers of 100 W and 150 W, respectively, at intervals of 1 min for 60 min under conditions where the indoor temperature was in the range 24.5~27.5℃, humidity was 35~40%, internal cooling temperature of the electrode was 20℃, size of the upper electrode was 250 mm, and the size of the lower electrode was 250 mm. The coefficients of determination of 150 W output power at the depth point of 5 cm from the central axis of the phantom were analyzed to be 0.9946 and 0.9926 in the agar and Gel Bolus phantoms, respectively; moreover, the temperature change equation of the agar and Gel Bolus phantoms with time can be expressed as follows in the state the phantom temperature is raised to 36℃: Y(G) is equation of Gel Bolus phantoms (in 5 cm depth) applying output power of 150 W. Y(G)=0.157X+36. It can be seen that if the temperature is measured in this case, the Gel Bolus phantom value can be converted to the measured value of the agar phantom. As a result of comparing the temperature distribution characteristics of the agar phantom of a human-body-equivalent material with those of the Gel Bolus phantom that can be continuously used, the usefulness of Gel Bolus phantom was exhibited.

Keyword

Ratio frequency hyperthermia device; dose distribution characteristic; agar phantom; Gel Bolus phantom

MeSH Terms

Agar*
Electrodes
Fever*
Humidity
Agar

Figure

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  Fig. 1. Making of agar phantom: (a) Agar phantom mold, (b) Agar powder of MSC Co. Ltd, (c) Sterile water, (d) Gel agar solidified with phantom, (e) Gel agar phantom separated from the mold, (f) Completed production of agar phantom.

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  Fig. 2. Gel bolus phantom.

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  Fig. 3. Illustration of the simulation model on the agar phantom.

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  Fig. 4. Illustration of the simulation model on the gel bolus phantom.

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  Fig. 5. Depth of measurement temperature on the agar phantom for 60 min at 100 W output power.

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  Fig. 6. Depth of measurement temperature on the agar phantom for 60 min at 150 W output power.

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  Fig. 7. Depth of measurement temperature on the gel bolus phantom for 60 min at 100 W output power.

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  Fig. 8. Depth of measurement temperature on gel bolus phantom for 60 min at 150 W output power.

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  Fig. 9. 5-cm depth for 60 min at 100 W output power for the temperature analysis of the agar and gel bolus phantoms.

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  Fig. 10. 5-cm depth for 60 min at 150 W output power for the temperature analysis of the agar and gel bolus phantoms.

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  Fig. 11. 10-cm depth for 60 min at 100 W output power for the temperature analysis of the agar and gel bolus phantoms.

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  Fig. 12. 10-cm depth for 60 min at 150 W output power for the temperature analysis of the agar and gel bolus phantoms.

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  Fig. 13. 15-cm depth for 60 min at 100 W output power for the temperature analysis of the agar and gel bolus phantoms.

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  Fig. 14. 15-cm depth for 60 min at 150 W output power for the temperature analysis of the agar and gel bolus phantoms.

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