TY - JOUR ID - 89908 TI - Determination of Collimator Helmet Factors for Leksell Gamma Knife 4C Unit Using GAF Chromic EBT3 Film and ImageJ Software JO - Asian Pacific Journal of Cancer Prevention JA - APJCP LA - en SN - 1513-7368 AU - Natesan, Ponnusamy AU - Palaniappan, Senthil Manikandan AU - M, Muthuvinayagam AU - Ganesh, K.M AU - Bhaskara Rao, Malla AD - National Institute of Mental Health and Neurosciences, Bengaluru, Karnataka, India. AD - Kidwai Memorial Institute of Oncology, Bengaluru, Karnataka, India. AD - Department of Physics, School of Advanced Sciences, Kalasalingam Academy of Research and Education, Tamilnadu, India. AD - National Institute of Mental Health and Neurosciences, Bengaluru, Karnataka, India. Y1 - 2021 PY - 2021 VL - 22 IS - 12 SP - 4031 EP - 4035 KW - Gamma knife Collimator factor KW - GAF chromic EBT3 film Dosimetry KW - ImageJ Software KW - Gamma Knife output factor DO - 10.31557/APJCP.2021.22.12.4031 N2 - Background: Measurement of Collimator helmet factors (CHF) is an important quality assurance procedure to be performed on Leksell Gamma Knife unit at regular interval to make sure that the interchangeable collimator helmet fit into the source channels without any positional inaccuracy which leads to major treatment error. The primary aim of this study is to measure the CHFs for Elekta Leksell Gamma knife 4C helmets using GafChromic EBT3 film and Image J software. Methods: GafChromic EBT3 film, EPSON expression 10000 XL scanner and Image J analysis software was used for this study. The calibration curve of GafChromic EBT3 film was generated with known dose values for 14 mm collimator helmet using ImageJ software. The collimator helmet factor (CHF) for 4mm, 8mm and 14 mm collimator helmets were measured by normalizing dose rates of 4mm, 8mm and 14 mm to the dose rate of 18 mm collimator helmet using the previously generated calibration curve. The measured CHF was compared to Elekta reference value and previously published mean values. Results: The measured CHFs were 0.896, 0.958, and 0.986 for 4mm, 8mm and 14mm collimators respectively. The percentage difference obtained was 1.7 %, 0.21 %, 0.1 % between measured values and reference values. Conclusion: The measurement of CHFs in LGK 4C unit using GafChromic EBT3 film and ImageJ software is a reliable method to verify the manufacturer quoted CHFs in routine quality assurance procedures.  UR - https://journal.waocp.org/article_89908.html L1 - https://journal.waocp.org/article_89908_af12605554a9f5674d5a26423f299862.pdf ER -