introduction radiotherapy planning systems require many percentage depth dose (pdd) and profile measurements and there are various dosimeters that can be used to obtain these scans. as dose perturbation is particularly troublesome in smaller photon fields, using a low-perturbation, unshielded electron field diode (efd) in these fields is of interest. the aim of this work was to investigate the ...

Introduction Radiotherapy planning systems require many percentage depth dose (PDD) and profile measurements and there are various dosimeters that can be used to obtain these scans. As dose perturbation is particularly troublesome in smaller photon fields, using a low-perturbation, unshielded electron field diode (EFD) in these fields is of interest. The aim of this work was to investigate the ...

introduction computed tomography scans are a very important tool for diagnosis and assessment of response to treatment in the practice of medicine. ionizing radiation in medical imaging is undoubtedly one of the most powerful diagnostic tools in medicine. yet, as with all medical interventions, there are potential risks in addition to the clear potential benefits. materials and methods two refe...

background: absolute dosimetry of external beam radiotherapy is carried out by the use of ionization chambers. these chambers must be calibrated at a standard dosimetry laboratory before any use in clinical dosimetry. the secondary standard dosimetry laboratory of iran (ssdl) has the duty of calibrating the ionization chambers used in radiotherapy centers in iran. materials and methods: the pre...

background: the effectiveness and safety of brachytherapy treatment is mainly concerned with the calibration of sources and their traceability to internationally accepted standards. secondary standard dosimetry laboratory (ssdl) does not offer calibration of ionization chambers with gamma-ray spectrum of high dose rate source 192ir . this work has been carried out to calibrate the high dose rat...

background: in order to deliver the precise dose to the target in radiotherapy, absorbed dose to water at the reference point should be assessed. when the calibration procedure is performed for a reference dosimeter in the 60co beam of a secondary standard dosimetry laboratory (ssdl), the total uncertainty in absorbed dose to water (dw) is estimated to be approximately 1.5%. this study attempts...

Introduction: The head scatter factor (Sc) is one of the important parameters for monitor unit (MU) calculation. There are multiple factors that impact the Sc values, such as, head structures, back scattering in to dose monitoring chambers, wedges and so on. This study aimed to investigate the variations of SC with different build-up cap materials, wall thickness, Source to ...

background: the aim of this work was to study the output factors for linac using different ionization chambers and build up caps. materials and methods: output factors were measured for open square fields (3 × 3 cm to 40 × 40 cm) defined by collimator jaws for 6 and 15 mv photon beams from a varian clinac 2100c accelerator were measured. the measurements in air were performed using compact cyli...