Even in examinations that did not exceed the DRL, patient protection can be optimised further by appropriate collimation of field size to that necessary for diagnosis.

Entrance surface radiation doses were measured with thermoluminescent dosimeters for 98 children who were referred to a cardiology department for the diagnosis or the treatment of a congenital heart disease. Additionally, all the radiographic parameters were recorded and Monte Carlo simulations were performed for the estimation of entrance surface dose to effective dose conversion factors, in order to further calculate the effective dose for each child. For diagnostic catheterisations the values ranged from 0.16 to 14.44 mSv, with average 3.71 mSv, and for therapeutic catheterisations the values ranged from 0.38 to 25.01 mSv, with average value 5 mSv. Effective doses were estimated for diagnostic procedures and interventional procedures performed for the treatment of five different heart diseases: (a) atrial septal defect (ASD), (b) ventricular septal defect (VSD), (c) patent ductus arteriosus (PDA), (d) aorta coarctation and (e) pulmonary stenosis. The high levels of radiation exposure are, however, balanced with the advantages of cardiac catheterisations such as the avoidance of surgical closure and the necessity of shorter or even no hospitalisation.

Computed tomography provides high-resolution imaging of the human body. However, it contributes mainly to the doses on the population. Additionally, the fact that children are two to three times more sensitive to the x rays compared to the adults results in the increased need of taking action for the reduction of the dose regarding the computed tomography examinations. The first part of this paper presents the results of an investigation on the variation of doses to children while the second part compares those results with the European standards. This project took place in twelve hospitals distributed throughout the country. The weighted computed dose-index and the dose length product were calculated for four different age-categories (namely 0, 1, 5 and 10-year-old) and for the three most often examinations (brain, thorax and abdomen). Effective dose values were estimated using coefficients and patients' data. The measurements showed that only a few hospitals are taking into account the protocols regarding the age of the children. As a result, many patients receive high doses without this being necessary. Thus, reducing dose methods should be adapted in order to improve the optimization of this high dose modality.

Seeking to assess the radiation risk associated with radiological examinations in neonatal intensive care units, thermo-luminescence dosimetry was used for the measurement of entrance surface dose (ESD) in 44 AP chest and 28 AP combined chest-abdominal exposures of a sample of 60 neonates. The mean values of ESD were found to be equal to 44 +/- 16 microGy and 43 +/- 19 microGy, respectively. The MCNP-4C2 code with a mathematical phantom simulating a neonate and appropriate x-ray energy spectra were employed for the simulation of the AP chest and AP combined chest-abdominal exposures. Equivalent organ dose per unit ESD and energy imparted per unit ESD calculations are presented in tabular form. Combined with ESD measurements, these calculations yield an effective dose of 10.2 +/- 3.7 microSv, regardless of sex, and an imparted energy of 18.5 +/- 6.7 microJ for the chest radiograph. The corresponding results for the combined chest-abdominal examination are 14.7 +/- 7.6 microSv (males)/17.2 +/- 7.6 microSv (females) and 29.7 +/- 13.2 microJ. The calculated total risk per radiograph was low, ranging between 1.7 and 2.9 per million neonates, per film, and being slightly higher for females. Results of this study are in good agreement with previous studies, especially in view of the diversity met in the calculation methods.

The purpose of this study was to estimate the radiation dose to which children are exposed during cardiac catheterizations for the treatment of ventricular and atrial septal defects. Radiation doses were estimated for 46 children aged 1-18 years. These children were treated for secundum atrial septal defects (ASD group) for perimembranous ventricular septal defects (VSD group) or underwent a routine diagnostic catheterization (diagnostic group). Thermoluminescent dosimeters (TLDs) were attached in locations, representing the lateral entrance dose, the posterior entrance dose, the thyroid dose, and the gonad dose, respectively. A dose area product (DAP) meter was also attached externally on the posterior-anterior (PA) tube to give a direct value in cGy cm(2) for each procedure. The patient's entrance dose from the PA field ranged from 1.5 to 185.0 mGy for all patients, while the lateral entrance dose varied from 0.9 to 204 mGy. Radiation exposure to the thyroid and the gonads was found to vary from 0.4 to 8.3 and 0.1 to 2.1 mGy, respectively. The DAP meter recorded DAP values for the posterior tube, between 46 and 3,700 cGy cm(2). The mean effective dose was found to be 7.7, 16.2, and 33.3 mSv for the diagnostic, the ASD, and the VSD group, respectively. Very strong correlation was found between the DAP values and the entrance radiation dose measured with TLDs. The mean entrance dose received from therapeutic cardiac catheterizations using the Amplatzer devices was found approximately twice the dose received from a diagnostic one. Even for the most complex procedures, the maximum entrance dose was at least 10 times lower than the threshold, associated with skin erythema.