the comparison of standard lead with individual mold shielding on patient dose

background: the shielding methods in radiotherapy due to delivering an accurate radiation dose to cancer tissues and avoiding unnecessary dose to normal tissues are very important. these methods include lead standard blocks, individual molding and multi leaf collimator (mlc). the mlc method is not still common in iran radiotherapy centers. individual molding is better than the lead block shielding because of lower operator error and time consuming. materials and methods: this study was performed in shahid ramazanzade radiotherapy center of yazd and intended to compare radiation dose due to the two shielding methods of lead and cerrobend. the radiation field sizes of head and neck, pelvis, and breast cancer treated by cobalt unit, 9mv, and 6mv photon beams of neptun and compact linear accelerators were studied, respectively. the absolute and relative dosimetry were achieved by farmer ionic chamber and diod detector. results: the absolute and relative dose values which were measured at the two shielding methods of lead standard and cerrobend individual molding were similar without significantly difference. conclusion: the miss difference dose between these two methods shielding and the advantages such as saving time, precision, and accuracy lead to preference of individual molding method rather than the lead block shielding.