TY - JOUR
T1 - Study of the penumbra for high-energy photon beams with Gafchromic™ EBT2 films
AU - Oh, Se An
AU - Kang, Min Kyu
AU - Yea, Ji Woon
AU - Kim, Sung Kyu
AU - Oh, Young Kee
PY - 2012/6
Y1 - 2012/6
N2 - The penumbra has a major impact on obtaining uniformity of isodose distributions in radiation therapy. The penumbra phenomena of intensity-modulated radiation therapy (IMRT) techniques using multi-leaf collimators (MLCs) has an impact on the dose distributions in the border of the target volumes and the MLC. The aim of this study was to determine the impact of high photon energy (6 MV, 10 MV) on the penumbra for various depths and field sizes by using the Pencil Beam Convolution algorithms (eclipse 8.6) and self-developing Gafchromic™ EBT2 film. For dose calculations and EBT2 measurements, we used an acryl phantom with dimensions 20 × 20 × 20 cm 3. The 200 cGy dose was delivered to the central depth (10 cm) of the acryl phantom. The result of this study was that increased energy, field size and depth are rise to an increased penumbra (20% ~80%) width. For a 6 MV photon energy, the penumbra widths (20%~80%) at 1.5 cm, 5 cm, and 10 cm depths were 4.2 mm, 4.4 mm, and 5.7 mm for the eclipse calculations and 2.9 mm, 4.1 mm, and 4.2 mm for the EBT2 film measurements for 10 × 10 cm 2 field sizes, respectively. For a 10 MV photon energy, the penumbra widths were 4.5 mm, 4.7 mm, and 6.2 mm for eclipse calculations and 4.1 mm, 4.6 mm, and 4.9 mm for EBT2 film measurements, respectively. As the field size was changed to 3 cm, 5 cm, 7 cm, 10 cm, and 15 cm, the penumbra widths changed to 5.1 mm, 5.3 mm, 5.6 mm, 5.9 mm, and 6.1 mm for eclipse calculations and 2.9 mm, 3.3 mm, 3.6 mm, 4.2 mm, and 5.1 mm for EBT2 measurements, respectively, for 10 cm depths for 6 MV photon energies. In this study, compared to the 10 MV photon energy, the 6 MV photon energy was preferred in treatments such as the 3D conformal radiation therapy and the IMRT for critical organs near the target volume.
AB - The penumbra has a major impact on obtaining uniformity of isodose distributions in radiation therapy. The penumbra phenomena of intensity-modulated radiation therapy (IMRT) techniques using multi-leaf collimators (MLCs) has an impact on the dose distributions in the border of the target volumes and the MLC. The aim of this study was to determine the impact of high photon energy (6 MV, 10 MV) on the penumbra for various depths and field sizes by using the Pencil Beam Convolution algorithms (eclipse 8.6) and self-developing Gafchromic™ EBT2 film. For dose calculations and EBT2 measurements, we used an acryl phantom with dimensions 20 × 20 × 20 cm 3. The 200 cGy dose was delivered to the central depth (10 cm) of the acryl phantom. The result of this study was that increased energy, field size and depth are rise to an increased penumbra (20% ~80%) width. For a 6 MV photon energy, the penumbra widths (20%~80%) at 1.5 cm, 5 cm, and 10 cm depths were 4.2 mm, 4.4 mm, and 5.7 mm for the eclipse calculations and 2.9 mm, 4.1 mm, and 4.2 mm for the EBT2 film measurements for 10 × 10 cm 2 field sizes, respectively. For a 10 MV photon energy, the penumbra widths were 4.5 mm, 4.7 mm, and 6.2 mm for eclipse calculations and 4.1 mm, 4.6 mm, and 4.9 mm for EBT2 film measurements, respectively. As the field size was changed to 3 cm, 5 cm, 7 cm, 10 cm, and 15 cm, the penumbra widths changed to 5.1 mm, 5.3 mm, 5.6 mm, 5.9 mm, and 6.1 mm for eclipse calculations and 2.9 mm, 3.3 mm, 3.6 mm, 4.2 mm, and 5.1 mm for EBT2 measurements, respectively, for 10 cm depths for 6 MV photon energies. In this study, compared to the 10 MV photon energy, the 6 MV photon energy was preferred in treatments such as the 3D conformal radiation therapy and the IMRT for critical organs near the target volume.
KW - EBT2 Gafchromic™ film
KW - PBC algorithms
KW - Penumbra (80% ~20%) width
UR - http://www.scopus.com/inward/record.url?scp=84863614312&partnerID=8YFLogxK
U2 - 10.3938/jkps.60.1973
DO - 10.3938/jkps.60.1973
M3 - Article
AN - SCOPUS:84863614312
SN - 0374-4884
VL - 60
SP - 1973
EP - 1976
JO - Journal of the Korean Physical Society
JF - Journal of the Korean Physical Society
IS - 11
ER -