超薄型熱發光劑量計量測臨床的皮膚劑量

Measurement of Clinical Skin Dose by Using Ultra-Thin Tlds

黃昭源(Chao-Yuan Huang) ； 林招膨(Jao-Perng Lin) ； 林松彥(Sung-Yen Lin) ； 朱鐵吉(Tieh-Chi Chu) ； 劉幕台(Mu-Tai Liu) ； 張東浩(Tung-How Chang) ； 謝長堯(Chang-Yao Hsieh)

《放射治療與腫瘤學》 7卷2期 (2000/06) Pp. 129-135

https://doi.org/10.6316/TRO/200007(2)129

摘要

目得：皮膚副作用是放射治療中主要的併發症，常造成必須中斷療程，是以對其做定量化的量測是重要且必須的。本研究利用超薄型熱發光劑量計量測在臨床不同照射情況下的皮膚劑量。
材料與方法：本研究利用超薄型熱發光劑量計( GR-200F，面積0.5×0.5 cm2，敏感層厚度5 mg．cm-2)量測6-15 MV光子及6-21 MeV電子，在不同照野面積( 10×10 cm2到40×40 cm2)及不同射 束入射角度( 0° 到 80° )下的皮膚劑量。對假體在覆蓋0 mm、3 mm、5 mm、10 mm厚的擬組織材料 ( bolus)下的皮膚劑量亦在量測之列。
結果與討論：對6、10與15 MV光子10×10 cm2照野，假體表面平均劑量與假體內最大劑量的比 值分別為16.10±0.68%、14.03±1.04%與10.59±0.64%，同時隨照野增加而增加。對6、9、 12、15、18與21 MeV電子，該值分別為72.59±1.72%、78.52±2.99%、78.89±2.86%、86.08± 2.62%、87.75 ± 1.94%與86.33 ± 3.0間，隨照野增加該值亦增加。此外，基底層傾斜因子隨射束入射角度增加而增加。
結論：對光子與電子假體表面平均PDD 1直隨照野增加而增加。基底層傾斜因子隨射束入射角度增 加而增加。擬組織材料(bolus)會增加皮膚劑量同時降低傾斜因子。

關鍵字

皮膚劑量,熱發光劑量計,基底層傾斜因子

並列摘要

Purpose: Skin complication is the main event of radiation therapy that interrupts the treatment schedule and is of important to quantify. This study measured the skin dose at some clinical setups by using ultra-thin TLDs.
Materials and Methods: Measurements were performed for 6-15 MV photons and 6-21 MeV electrons with ultra-thin TLDs (GR-200F, surface area 0.5 x 0.5 cm2, nominal thickness 5 mg. cm-2 of sensitive layer). The skin dose of various field sizes, ranging from 10 x 10 cm2 to 40 x 40 cm2, and incident angle )f beam, from 0°to 80°, were measured. The measurements were also performed for the skin dose on phantom with 0 mm, 3 mm, 5 mm and 10 mm bolus covered.
Results and Discussion: The ratios of mean surface dose to maximum dose in phantom for 10 x 10 cm2 are 16.1O±0.68%, 14.03± 1.04% and 10.59±0.64% for 6, 10 and 15 MY respectively, increasing with increased field size. For electrons, the ratios are 72.59± 1.72%, 78.52± 2.99%, 78.89 ± 2.86%, 86.08± 2.62%, 87.75± 1.94% and 86.33± 3.09% for 6, 9, 12, 15, 18 and 21 MeV respectively, increasing with increased field size. The basal layer oblique factors increase with increased incident angle.
Conclusion: The mean PDD value of skin increases with increased field size for both photons and electrons. The basal layer oblique factor increases with increased incident angle. The bolus will increase the skin dose and eliminate the oblique factor.

並列關鍵字

Skin dose,TLO,Basal layer oblique factor