Investigation of Backscatter Factors in Chest Radiography Technique Using Water Phantom and Nanodot Dosimeters

In general diagnostic radiology, patient dose can be estimated from surface dose by using phantom. It can be also determined without phantom by obtaining the air kerma dose value and then multiply with backscatter factor (BSF). There are a lot factors those affect the BSF value. The purpose of the study was to investigate the parameters that may affect the BSF for chest radiography technique with two common locations of imaging detector which are chest stand and under bed bucky. Two different sizes of water phantom were used in the study. These phantoms were exposed to direct beam with different beam sizes, source image distances (SID) and beam quality. The dose measurement in air was carried out by using ion chamber and nanodot. Then, the nanodots were used to determine the surface dose on the phantoms. These values were collected and used to calculate the BSF value. The parameters affect the value of BSF were discussed in detail in the paper. The BSF increased with large field and phantom size, high SID and beam quality of X-ray. (author)