BACKGROUND: Recently it was data wise established that there is a considerable dose difference due to source position from the surface of the patient, and due to the presence of inhomogeneities. AIM: It aims at to find out the dose difference due to source position, and inhomogenieties in water phantom of high dose rate (HDR)(192) Ir mHDR-v2 source by experiment and by Monte Carlo (MC) simulation GEANT4 code. MATERIALS AND METHODS: The measured study of the source was done using an in-air ionization chamber, water phantom while the calculated study was done by modeling the water phantom and its water, inhomogeneities, position of source, and points of calculation. RESULTS: The measured and calculated dose differences are 5.48 to 6.46% and 5.43 to 6.44% respectively higher in the presence of dry air and 4.40 to 4.90% and 4.38 to 4.88% respectively lower in the presence of cortical bone. However, for the study of the effect of source position on dose distribution, when the source was positioned at a 1 cm distance from the surface of water phantom, the near points between 1 cm and 2 cm are 2 to 3.5% and 2.1-3.7% underdose and for distant points from 3 cm to 8 cm from the source are 4 to 15% and 4.1 to 15.8% underdose for measured and calculated studies, respectively, to the dose when the source was positioned at midpoint of water phantom. CONCLUSION: These results can be used in the treatment planning system.
BACKGROUND: Recently it was data wise established that there is a considerable dose difference due to source position from the surface of the patient, and due to the presence of inhomogeneities. AIM: It aims at to find out the dose difference due to source position, and inhomogenieties in water phantom of high dose rate (HDR)(192) Ir mHDR-v2 source by experiment and by Monte Carlo (MC) simulation GEANT4 code. MATERIALS AND METHODS: The measured study of the source was done using an in-air ionization chamber, water phantom while the calculated study was done by modeling the water phantom and its water, inhomogeneities, position of source, and points of calculation. RESULTS: The measured and calculated dose differences are 5.48 to 6.46% and 5.43 to 6.44% respectively higher in the presence of dry air and 4.40 to 4.90% and 4.38 to 4.88% respectively lower in the presence of cortical bone. However, for the study of the effect of source position on dose distribution, when the source was positioned at a 1 cm distance from the surface of water phantom, the near points between 1 cm and 2 cm are 2 to 3.5% and 2.1-3.7% underdose and for distant points from 3 cm to 8 cm from the source are 4 to 15% and 4.1 to 15.8% underdose for measured and calculated studies, respectively, to the dose when the source was positioned at midpoint of water phantom. CONCLUSION: These results can be used in the treatment planning system.