Alam, M JahangirRabbani, K SZakaria, G AHussain, S M AkramKiber, AdnanBaig, Tanvir2007-12-122009-05-272007-12-122009-05-272007-12-12Alam MJ, Rabbani KS, Zakaria GA, Hussain SM, Kiber A, Baig T. A modified formula for defining tissue phantom ratio of photon beams. Bangladesh Medical Research Council Bulletin. 2007 Dec; 33(3): 92-7http://imsear.searo.who.int/handle/123456789/258Bangladesh Medical Research Council Bulletin.Tissue phantom ratio (TPR), for square fields of various dimensions has been determined at varying depths in water. The dose in water has been measured at a fixed source-to-surface distance (SSD) of 100 cm and reference depth of 5 cm for 6 MV photon beam of Siemens Linear Accelerator Primus 11 in German Cancer Research Center (DKFZ), Heidelberg, Germany. A modified formula has been developed to calculate the TPR value for isocentric treatment. The present article describes the conversion of the measured data values into a comprehensive and consistent data set by the modified formula, that gives the TPR from Percentage Depth Dose (PDD) with depth as a function of field sizes from 10 mm x 10 mm upto 300 mm x 300 mm) and depth (from 0 mm to 300 mm).engAbsorptiometry, Photon --instrumentationHumansModels, TheoreticalPhantoms, ImagingPhotonsRadiometry --instrumentationJournal Article