Extremity and eye lens dosimetry for medical staff performing vertebroplasty and kyphoplasty procedures.

Measurements of doses to hands, legs and eyes are reported for operators in four different hospitals performing vertebroplasty or kyphoplasty. The results confirm that occupational doses can be high for interventional spine procedures. Extremity and eye lens doses were measured with thermoluminescent dosimeters positioned on the ring fingers, wrists, legs and near the eyes of interventional radiologists and neurosurgeons, over a period of 15 months. Doses were generally larger on the left side for all positions monitored. The median dose to the left finger was 225 µSv per procedure, although a maximum of 7.3 mSv was found. The median dose to the right finger was 118 µSv, but with an even higher maximum of 7.7 mSv. A median left eye dose of 34 µSv (maximum 836 µSv) was found, while the legs received the lowest doses with a median of 13 µSv (maximum 332 µSv) to the left leg. Annual dose to the hand assessed by the cumulated doses almost reached the annual dose limit of 500 mSv, while annual dose to the eyes exceeded the eye lens dose limit of 20 mSv yr(-1). Different x-ray systems and radiation protection measures were tested, like the use of lead gloves and glasses, tweezers, cement delivery systems and a magnetic navigation system. These measurements showed that doses can be significantly reduced. The use of lead glasses is strongly recommended for protection of the eyes.

SECONDARY NEUTRON DOSES IN A PROTON THERAPY CENTRE.

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.

Influence of standing positions and beam projections on effective dose and eye lens dose of anaesthetists in interventional procedures.

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.

Mouse one-cell embryos undergoing a radiation-induced G2 arrest may re-enter S-phase in the absence of cytokinesis.

PCC (premature chromosome condensation) can be used for visualizing and scoring damage induced by radiation in the chromatin of cells undergoing a G1 or G2 arrest. A method involving the fusion of irradiated single embryonic cells with single MI oocytes was used to induce PCC in mouse zygotes of the BALB/c strain, which suffer a drastic G2 arrest after X-irradiation (dose used 2.5 Gy). Other G2-arrested embryos were exposed in vitro to the phosphatase inhibitor calyculin A. Both methods furnished excellent chromosome preparations of the G2-arrested embryos. The mean number of chromosome fragments did not change significantly during G2 arrest, suggesting that zygotes of this strain are unable to repair DNA damage leading to such aberrations. Forty to fifty percent of the irradiated embryos were unable to cleave after G2 arrest and remained blocked at the one-cell stage for a few days before dying. PCC preparations obtained from such embryos suggested that about 30% of them had undergone a late mitosis not followed by cytokinesis and had entered a new DNA synthesis. These results are discussed in the light of recent observations in irradiated human cells deficient in the p53/14-3-3sigma pathway.