@article { author = {Tahmasebi Birgani, Mohammad Javad and Chegni, Nahid and Tahmasbi, Marziyeh and Fayazi, Raziye and Fatahi Asl, Jafar and Behrouz, Mohammad Ali}, title = {Calculation of Equivalent Square Fields in Radiation Therapy by an Improved Vadash Correction Factor for Collimator Exchange Effects}, journal = {Asian Pacific Journal of Cancer Prevention}, volume = {19}, number = {11}, pages = {3053-3057}, year = {2018}, publisher = {West Asia Organization for Cancer Prevention (WAOCP), APOCP's West Asia Chapter.}, issn = {1513-7368}, eissn = {2476-762X}, doi = {10.31557/APJCP.2018.19.11.3053}, abstract = {Background and objectives: To determine the head scatter factor, a formalism presented by Vadash and Bjärngardhas been employed to assess collimator exchange effects. The aim of this study was to determine the best Vadashcorrection factor (A) by introducing a new method based on the output factor measured in air for different square andrectangular fields. Materials and Methods: A new simple mathematical method based on selection of the best dosimetricdata was proposed to obtain the A value for Vadash to predict the equivalent square field size. Measurements wereperformed with a Farmer c}, keywords = {}, url = {https://journal.waocp.org/article_73919.html}, eprint = {https://journal.waocp.org/article_73919_dcbfcde9191090ae21a5c45c9d5fec35.pdf} }