[Quality control--patient doses--guidance dose levels from diagnostic radiology in Tunisia].

Background: Radiation doses from diagnostic radiology are the most important exposure collective doses of the man. Entrance Surface Dose is one of the basic dosimetric quantities for measuring the patient dose and hence, an excellent tool for optimization purposes and for comparison with the international reference values.

Aim: The aim of the study was to assess the delivred quantitis of rayon x to patients who undervent radiography;

Methods: For the first time in Tunisia the doses delivered to the patient undergoing the most common type of X ray examinations (chest, abdomen, lumbar spin) were performed in two university hospitals of Tunis.

[Radon in Tunisian buildings].

Radon is a natural radioactive gas produced by decay of uranium and radium present in soils. Diluted in air, in confined atmospheres, it may accumulate in high concentrations. Inhalation of radon and its progeny is thought to increase lung cancer risk.

Radon concentrations in some dwellings of Tunisia.

Indoor air radon concentrations are still unknown in Tunisia. For the first time, they have been determined in several regions of the country using open alpha track dosimeters containing LR-115 film. Measurements were taken in 69 dwellings located around greater Tunis during 1 y, changing dosimeters every 2 mo.

An investigation of entrance surface dose calculations for diagnostic radiology using Monte Carlo simulations and radiotherapy dosimetry formalisms.

Our aim in this work was to investigate the methodology used in the determination of the entrance surface dose (ESD) in diagnostic radiology. In kV x-rays for low-energy photons (tube potential up to 160 kV, HVL: 1-8 mm Al), the ESD is based on the use of the ratio of mass-energy absorption coefficients and backscatter factors. A full simulation of the photon and electron transport in a kilovoltage x-ray unit, using the Monte Carlo code BEAM/EGS4, was performed to obtain an accurate beam phase space for use in dose calculation.