Evaluation of the effective energy of primary and transmmitted workload weighted X-ray spectra

Current methods for X-ray shielding evaluation for imaging facilities do not take into account the effective energy of the radiation impinging on primary barrier. In addition, the X-ray beam attenuation through the patient is not considered in radiation shielding. The proposed models do not deal with the hardening of the spectra between the primary and transmitted beams. Therefore, the present work proposes the evaluation of X-ray spectra transmitted by an adult patient (anthropomorphic phantom) and a shielding barrier weighted by typical workload distributions. A set of primary spectra produced by a voltage range from 60 to 140 kV was measured with a CdTe spectrometer system. A second set of X-ray spectra transmitted through a 15 mm thickness barite mortar plate was also measured employing the same beam quality and voltage range. The air-kerma was simultaneously measured using an ionization chamber. The primary and transmitted experimental X-ray spectra were weighted by a typical chest examination workload distribution. The resulting weighted spectra represent the superposition of the radiation beams typically used in chest examinations. The effective energy of primary weighted spectra was estimated in 42.4 keV and the effective energy of the corresponding transmitted spectra was estimated in 64.7 keV. - Highlights: • Evaluation of weighted spectra by typical workload distributions is proposed. • Measurements of primary and transmitted X-ray spectra were performed. • Photons energy distribution should be considered in shielding calculations