Measurement of backscatter factor for kilovoltage x-ray beam using ionization chamber and Gafchromic XR-QA2 film

International Nuclear Science, Technology and Engineering Conference 2017

原子能学

Ab Shukor, N.S.^1 ; Mohd Asri, N.H.^1 ; Syed Jaafar, S.M.F.^1 ; Rosnan, M.S.^2 ; Abdul Aziz, S.A.^1

School of Health Sciences, Health Campus USM, Universiti Sains Malaysia, Kelantan, Malaysia^1

Radiology Department, Hospital Universiti Sains Malaysia, Kelantan, Malaysia^2

关键词: Average difference;    Effective energy;    Field size;    Film measurement;    Film study;    Small field size;    Surface dose;    Tube voltages;   

Others  :  https://iopscience.iop.org/article/10.1088/1757-899X/298/1/012043/pdf
DOI  :  10.1088/1757-899X/298/1/012043

来源: IOP

【 摘 要 】

Backscatter factor (BSF) is an important parameter in the determination of surface dose for kilovoltage X-ray beam. The purpose of this study was to measure the BSF for kilovoltage diagnostic X-ray beam, and compare the measured BSF between Gafchromic XR-QA2 film and shadow free (SFD) ionization chamber (IC). The parameters that may affect the BSF, such as tube voltage (kVp) and field size, were also studied. The results were in good agreement with the TRS 457, with deviation of less than 12 %. Based on the film study, the BSF obtained from the film measurement were found to be lower than that of the IC, with average difference of 26 %. It was also found that smaller field size resulted in lower effective energy, and the amount of photons which scattered back onto the surface were also smaller. This study demonstrated that the Gafchromic XR-QA2 film was not suitable for the application of small field size.