The use of cone beam computed tomography (CBCT) in diagnostic radiology departments is increasing. Several discussions arise whether with the CBCT application, some multi-slice CT (MSCT) examinations can be replaced by it. High hopes are set regarding the dosimetric aspects of CBCT: are patient doses in between those of conventional X-rays and MSCT? In this study, effective dose and organ doses were evaluated for two non-dental CBCT examinations: sinus and middle ear. A comparison with the dose obtained with a MSCT protocol was performed. Moreover, the sinus examination was also compared with the dose obtained by projection radiography (RX). Effective doses were estimated from thermoluminescent detector dose measurements in an anthropomorphic phantom and were compared against Monte Carlo simulations. Results show that the effective dose for the sinus examination is more than three times higher with MSCT than with CBCT and about five times lower with RX compared with CBCT, whereas for the middle ear examination, the effective dose obtained with MSCT is almost six times higher than that of CBCT. Finally, a sensitivity study on the size and position of the CBCT field of view showed the influence of these two factors on the dose received by the patient.

The performance of a single or double dosimetry (SD or DD) algorithm on estimating effective dose wearing radioprotective garments (ERPG) depends on the specific irradiation conditions. This study investigates the photon energies and angles of incidence for which the estimation of ERPG with the personal dose equivalents measured over and under the RPG (Ho and Hu) becomes more challenging. The energy and angular dependences of ERPG, Ho and Hu were Monte Carlo calculated for photon exposures. The personal dosimeter of SCK · CEN was modeled and used to determine Ho and Hu. Different SD and DD algorithms were tested and critical exposure conditions were identified. Moreover, the influence of calibration methods was investigated for the SCK · CEN dosimeter when worn over RPG. We found that the accuracy with which ERPG is calculated using SD and DD is strongly dependent on the energy and angle of incidence of photons. Also, the energy of the photon beam used to calibrate the Ho dosimeter can bias the estimation of ERPG.

More and more anaesthetists are getting involved in interventional radiology procedures and so it is important to know the radiation dose and to optimise protection for anaesthetists. In this study, based on Monte Carlo simulations and field measurements, both the whole-body doses and eye lens dose of anaesthetists were studied. The results showed that the radiation exposure to anaesthetists not only depends on their workload, but also largely varies with their standing positions and beam projections during interventional procedures. The simulation results showed that the effective dose to anaesthetists may vary with their standing positions and beam projections to more than a factor of 10, and the eye lens dose may vary with the standing positions and beam projections to more than a factor of 200. In general, a close position to the bed and the left lateral (LLAT) beam projection will bring a high exposure to anaesthetists. Good correlations between the eye lens dose and the doses at the neck, chest and waist over the apron were observed from the field measurements. The results indicate that adequate arrangements of anaesthesia device or other monitoring equipment in the fluoroscopy rooms are useful measures to reduce the radiation exposure to anaesthetists, and anaesthetists should be aware that they will receive the highest doses under left lateral beam projection.

The formation of secondary high-energy neutrons in proton therapy can be a concern for radiation protection of staff. In this joint intercomparative study (CERN, SCK•CEN and IBA/IRISIB/ULB), secondary neutron doses were assessed with different detectors in several positions in the Proton Therapy Centre, Essen (Germany). The ambient dose equivalent H(*)(10) was assessed with Berthold LB 6411, WENDI-2, tissue-equivalent proportional counter (TEPC) and Bonner spheres (BS). The personal dose equivalent Hp(10) was measured with two types of active detectors and with bubble detectors. Using spectral and basic angular information, the reference Hp(10) was estimated. Results concerning staff exposure show H(*)(10) doses between 0.5 and 1 nSv/monitoring unit in a technical room. The LB 6411 showed an underestimation of H(*)(10), while WENDI-2 and TEPC showed good agreement with the BS data. A large overestimation for Hp(10) was observed for the active personal dosemeters, while the bubble detectors showed only a slight overestimation.

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