Skin dose measurement by using ultra-thin TLDs

The treatment schedule for radiation therapy is often interrupted because o f complicated skin reactions. Quantitative information relating beam parame ters and skin reactions will be helpful. Measurements were performed for 6- 15 MV photons and 6-21 MeV electrons with ultra thin TLD films (GR-200F. su rface area 0.5 x 0.5cm(2). nominal thickness 5 Mg cm(-2)). The skin doses f or various field sizes, ranging from 10 x 10 to 40 x 40 cm(2). and various incident angles of beam from 0 degrees to 80 degrees were measured. The rat ios of skin dose to maximum dose in phantom for 10 x 10 cm(2) are 16.10 +/- 0.68% 14.03 +/- 1.04% and 10.59 +/- 0.64% for 6, 10 and 15 MV, respectivel y. Such ratios increase with a larger 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, respectiv ely. They also increase with a larger size. The oblique factors also increa se with larger incident angle. (C) 2001 Elsevier Science Ltd. All rights re served.