THE USE OF ACTIVE PERSONAL DOSEMETERS IN INTERVENTIONAL WORKPLACES IN HOSPITALS: COMPARISON BETWEEN ACTIVE AND PASSIVE DOSEMETERS WORN SIMULTANEOUSLY BY MEDICAL STAFF

Medical staff in interventional procedures are among the professionals with the highest occupational doses. Active personal dosemeters (APDs) can help in optimizing the exposure during interventional procedures. However, there can be problems when using APDs during interventional procedures, due to the specific energy and angular distribution of the radiation field and because of the pulsed nature of the radiation. Many parameters like the type of interventional procedure, personal habits and working techniques, protection tools used and X-ray field characteristics influence the occupational exposure and the scattered radiation around the patient. In this paper, we compare the results from three types of APDs with a passive personal dosimetry system while being used in real clinical environment by the interventional staff. The results show that there is a large spread in the ratios of the passive and active devices.

Fluid-bed microencapsulation of ascorbic acid

Ascorbic acid has been fluidized and microencapsulated with three different hydrophobic coating materials by the top-spray method. The experiments were conducted with polymethacrylate coating material formulated as a water dispersion, and ethyl-cellulose and waxy coating material both formulated as organic solutions. Characteristics of the fluidized bed procedure in conical geometry have been determined by estimation of two parameters: bed porosity and total pressure drop. A satisfactory agreement between experimental and calculated values has been reached. The following properties of the microencapsulated ascorbic acid have been determined: core content, bulk and tapped density, crystal size distribution prior and after microencapsulation, surface morphology and release profile. The comparison and evaluation of different hydrophobic coating materials have been performed on the basis of these findings.