Primary DNA damage assessed with the comet assay and comparison to the absorbed dose of diagnostic X-rays in children.

The aim of this work is to assess DNA damage in peripheral blood lymphocytes of children prior to and following airway X-ray examinations of the chest using the alkaline comet assay and to compare data with the measured absorbed dose. Twenty children with pulmonary diseases, between the ages of 5 and 14 years, are assessed. Absorbed dose measurements are conducted for posterior-anterior projection on the forehead, thyroid gland, gonads, chest, and back. Doses are measured using thermoluminescent and radiophotoluminescent dosimetry systems. Differences between tail lengths, tail intensity, and tail moments as well as for the long-tailed nuclei before and after exposures are statistically significant and are dependent on the individual. The results demonstrate the usefulness of the comet assay as a measure of X-ray damage to lymphocytes in a clinical setting. Doses measured with both dosimeters show satisfactory agreement (0.01 mSv) and are suitable for dosimetric measurements in X-ray diagnostics.

Estimation of the absorption coefficients of two-layered media by a simple method using spatially and time-resolved reflectances.

Our newly developed method using spatially and time-resolved reflectances can easily estimate the absorption coefficients of each layer in a two-layered medium if the thickness of the upper layer and the reduced scattering coefficients of the two layers are known a priori. We experimentally validated this method using phantoms and examined its possibility of estimating the absorption coefficients of the tissues in human heads. In the case of a homogeneous plastic phantom (polyacetal block), the absorption coefficient estimated by our method agreed well with that obtained by a conventional method. Also, in the case of two-layered phantoms, our method successfully estimated the absorption coefficients of the two layers. Furthermore, the absorption coefficients of the extracerebral and cerebral tissue inside human foreheads were estimated under the assumption that the human heads were two-layered media. It was found that the absorption coefficients of the cerebral tissues were larger than those of the extracerebral tissues.

Radiation exposure to the orthopaedic surgeon during periacetabular osteotomy.

The objective of this study was to directly measure the radiation exposure to the orthopaedic surgeon and to measure dose points to the surgeon's fingers, thyroid gland, and forehead during intraoperative fluoroscopy in periacetabular osteotomy (PAO). In a series of 23 consecutive periacetabular osteotomy procedures, exposure monitoring was carried out using thermo luminescent dosimeters. The effective dose received by the operating surgeon was 0.008 mSv per operation which adds up to a yearly dose of 0.64 mSv from PAO. The median point equivalent dose (mSv) exposure under PAO was 0.009 for the forehead and thyroid gland, 0.045 for the right index finger, and 0.039 for the left index finger. The effective estimated yearly dose received by the operating surgeon was very low. Wearing a lead collar reduces radiation exposure to the thyroid gland while the lead gloves did not protect the surgeon's fingers.

The use of extremity dosemeters in a hospital environment.

A general overview is given on the use of extremity dosemeters, their calibration, the units and phantoms to be used. One of the major applications of extremity dosemeters is to monitor the personnel in a hospital environment. In nuclear medicine, brachytherapy and interventional radiology (IR) skin doses to hands and legs can be substantial. Here, we report on two studies that are presently being undertaken in Belgium. The first one tries to map the dose distribution on the hands, in function of the manipulation in nuclear medicine. Some preliminary results are also given from a nationwide survey study for patient and personnel doses during IR and cardiology. The radiologists' hands, legs and forehead are monitored during a whole range of procedures in different hospitals.

[Effective dose and dose to the crystalline lens during angiographic procedures]. / Dose efficace et dose au cristallin lors des procedures angiographiques.

Interventional radiology presents the highest dose levels for the staff and for the patient. For a total of 34 angiographic examinations the doses at the forehead and at the neck of a radiologist have been measured. The effective dose and the dose to the eye lens have been estimated over a period of one year. Doses to the lens of the eye close to the limit of 150 mSv proposed by the ICRP have been observed. There is an imminent need for the radiologist to wear also lead glasses to avoid formation of cataracts at long term.

A comparison of human- and headform-based measurements of solar ultraviolet B dose.

New data on the distribution of solar ultraviolet B (UVB) radiation on the face are presented. Measurements made on human subjects and on rotating headform models are compared, and the effect of altering the orientation of the headform is considered. For a range of postures (standing, sitting, bending, kneeling) a corresponding headform angle (20 degrees, 30 degrees, 40 degrees, 60 degrees respectively) is determined that gives improved agreement with human-based measurements. This suggests that a more realistic simulation of human exposure is achieved by appropriately tilting the model.

Assessment with TLD of radiation exposure to staff during radium insertions in cancer of cervix.

A radiation protection survey has been carried out using TLD to assess the radiation exposure to staff during radium insertions for cancer of the cervix. The staff monitored were the radiotherapist, anaesthetist and operating theatre assistant. The radiotherapist, who received the highest exposure, had on the average 160 muGy (16 mrad) whole body (chest) dose while the finger tip doses were around 600 muGy (60 mrad) from the insertion of 60 mg radium. TLD was found to be convenient and sensitive for this purpose, including estimation of finger-tip doses. It helps to maintain the confidence of the staff that their doses are "as low as readily achievable" and also offers a means of checking improvements in practice where found necessary.