Use of the VIP-man model to calculate energy imparted and effective dose for x-ray examinations

A male human tomographic model was used to calculate values of energy imparted (ε) and effective dose (E) for monoenergetic photons (30-150 keV) in radiographic examinations. Energy deposition in the organs and tissues of the human phantom were obtained using Monte Carlo simulations. Values of E/ε were obtained for three common projections [anterior-posterior (AP), posterior-anterior (PA), and lateral (LAT)] of the head, cervical spine, chest, and abdomen, respectively. For head radiographs, all three projections yielded similar E/ε values. At 30 keV, the value of E/ε was ∼1.6 mSv J^-1, which is increased to ∼7 mSv J^-1 for 150 keV photons. The AP cervical spine was the only projection investigated where the value of E/ε decreased with increasing photon energy. Above 70 keV, cervical spine E/ε values showed little energy dependence and ranged between ∼8.5 mSv J^-1 for PA projections and ∼17 mSv J ^-1 for AP projections. The values of E/ε for AP chest examinations showed very little variation with photon energy, and had values of ∼23 mSv J^-1. Values of E/ε for PA and LAT chest projections were substantially lower than the AP projections and increased with increasing photon energy. For abdominal radiographs, differences between the PA and LAT projections were very small. All abdomen projections showed an increase in the E/ε ratio with increasing photon energy, and reached a maximum value of ∼13.5 mSv J^-1 for AP projections, and ∼9.5 mSv J ^-1 for PA/lateral projections. These monoenergetic E/ε values can generate values of E/ε for any x-ray spectrum, and can be used to convert values of energy imparted into effective dose for patients undergoing common head and body radiological examinations.