155 Radiation Protection Dosimetry Vol. 80, Nos 1–3, pp. 155–158 (1998) Nuclear Technology Publishing ASSESSMENT OF DOSES TO PATIENTS SUBMITTED TO FLUOROSCOPIC GASTROINTESTINAL TRACT EXAMINATIONS L. V. Canevaro†‡, M. T. Carlos§, J. C. Borges†, G. Drexler‡ and H. A. Koch †Programa de Engenharia Nuclear/COPPE/Universidade Federal do Rio de Janeiro, Brazil ‡Laborato ´rio de Cie ˆncias Radiolo ´gicas/Universidade do Estado de Rio de Janeiro Rua Sa ˜o Francisco Xavier, 524. Pav. H. L. da Cunha – Sala 136 CEP 20550–013. Maracana ˜, Rio de Janeiro, Brazil; and GSF - National Research Center for Environment and Health Institute for Radiation Protection 85764 Neuherberg, Germany §Instituto de Radioprotec ¸a ˜o e Dosimetria/Comissa ˜o Nacional de Energia Nuclear (IRD/CNEN), Brazil Servic ¸o de Radiodiagno ´stico/Hospital Universita ´rio/UFRJ, Brazil Abstract — Doses to the skin in patients undergoing fluoroscopic examinations of the gastrointestinal tract were measured. Barium swallow (BS), barium meal (BM) and double contrast barium enema (DCBE) examinations were assessed. Two pro- cedures for calibration of the thermoluminescence dosemeters (TLD) used are discussed, free-in-air and with scattering tissue- equivalent medium in the diagnostic range of energies. The use of equipment with and without image intensifier (II-TV), which still operates in Brazil, were used for carrying out examinations. The high dose values which resulted from some procedures using fluorescent screen (without II-TV) make the use of this type of machine unacceptable. INTRODUCTION Fluoroscopy is a very useful diagnostic tool which allows the assessment of dynamic functions of an organ- ism. However, fluoroscopic examinations usually cause more exposure to the individual patient. Hence, these procedures deserve special attention as far as optimis- ation procedures are concerned. With some fluoroscopic equipment, the doses deliv- ered to the patient can be very high, sometimes produc- ing localised reactions of deterministic character. Doses depend also on both examination time and total number of radiographs (1,2) , besides other factors. The assessment of doses from fluoroscopic investigations has always been complex, mainly due to the dynamic nature of the examinations. A single examination consists of several X ray fields with different dimensions, localised in dif- ferent anatomical regions of the patient’s body using various radiation qualities and irradiation times (3) . ICRP (4,5) recommends the application of dose refer- ence levels as a quantitative guideline in order to priorit- ise more effective actions for dose reduction. In fluor- oscopy, dose-area product (DAP) seems to be a practical quantity to express the reference levels. In Brazil, like many other Latin American countries, DAP meters are not yet routinely used and perhaps practical application of DAP will not be carried out soon. On the other hand, in some facilities, fluoroscopic gastrointestinal investi- gations are performed using old fashioned equipment without image intensifiers (II-TV), i.e. fluorescent screens in darkness. This happens at the same time as more complex and modern equipment can be found. In this situation some questions have been raised: What are the radiation levels that the patients are receiv- ing? and, What are the feasible parameters to measure these radiation levels under local conditions? This work presents a simple methodology of easy applicability using the infrastructure of a thermolumi- nescence dosimetry laboratory installed at IRD/CNEN. It measures doses to skin in standardised sampling points for each kind of gastrointestinal investigation. This first exercise was performed at the Hospital Univ- ersita ´rio da Universidade Federal do Rio de Janeiro, where fluoroscopic equipment with II-TV and fluor- escent screens have been installed. Radiation measurements in patients by using equip- ment without II-TV can be an opportunity to obtain a general view for applying a retrospective dose assess- ment in countries that have eliminated this practice. MATERIALS AND METHODS Diagnostic equipment and techniques Doses to the skin were assessed on patients undergo- ing barium swallow (BS), barium meal (BM) and double contrast barium enema (DCBE) examinations, using X ray equipment with and without II-TV (6) . Two Siemens Tridoros 150 machines, with undercouch tube, an overtable fluoroscope, without II-TV (designed as A and B equipment) and one CGR Maximans 125 S machine, with overcouch tube, an undertable fluoro- scope, with II-TV (designed as C) were used for the examinations. Kilovoltage, milliamperage, number of radiographs, time exposure and patient thickness were recorded for each investigation. In the radiography phase, the radio- graphic techniques used were similar with both types of equipment: 70–100 kV p and 12–16 mA.s. In the fluor- oscopy phase, the current applied at A and B equipment ranged between 1– 4 mA, while at C equipment current