چاپ صفحه |  صفحه نخست سامانه |  نویسندگان |  اطلاعات تفضیلی |  دانلود مقاله | دانشگاه علوم پزشکی تبریز |
| نویسنده | نفر چندم مقاله |
|---|---|
| پریناز محنتی | اول |
| عنوان | متن |
|---|---|
| خلاصه مقاله | An investigation of collimator scatter factor with variations of ionization chambers thickness and type of buildup caps in the wedged fields for 6 MV photon beams Abstract Introduction The head scatter factor (Sc) is one of important components in dose measurement systems in radiotherapy. SC is affected by the scattering photon from different components of treatment head like primary collimator, flattening filter, secondary collimator, dose moni-tor chamber and wedge to measure the Sc, it is important to design the buildup cap or mini phantom, to use together with a suitable detector. The buildup cap thickness should provide full charged particle equilibrium (CPE) as in water medium, without any photon scattering, and be small enough to be fully covered by the radiation beam. The thickness of buildup cap should be equal to the depth of maximum dose (Dmax), to provide CPE. This study aimed to investigating the effect of different ionizing chambers and builds up caps and depth of measurement on the SC in open and wedged fields. Materials and Methods: The head scatter factor were measured for open and wedged square fields sizes(5 x 5 cm to 25 x 25cm) from an Elekta compact medical linear accelerator(6MV). The measurements in air were performed using RK and Farmer type ionization chamber fitted with Perspex and copper build up caps. To measurement the SC, miniphantom was positioned in a stand vertical to the beam central axis. Results: Researches showed that output factors increased with field size of treatment. The head scatter factor increased with wedged field sizes and wedge angles. Also, SC value depends on the type of material (atomic number) of buildup caps, No significant difference was found for both ionization chambers and variation of Source Skin distance (SSD). Conclusion: Variation on the field size and material of buildup were effective on the collimator scatter factor. |
| کلمات کلیدی | Buildup cap; collimator scatter factor; ionization chamber; wedged |
| نام فایل | تاریخ درج فایل | اندازه فایل | دانلود |
|---|---|---|---|
| certification of An investigation.pdf | 1399/04/15 | 163945 | دانلود |
| An Investigation of Collimator-134-135.doc | 1399/04/01 | 3802624 | دانلود |
