In a 1991 report, the capital city, San Jose had about 1.11 million inhabitants. The Costa Rican social security system, which is mandated to provide medical cover, reported 90% coverage for the population. The life expectancy was reported to be at 75.2 years between the years 1990 and 1995. Integral in the treatment of cancer in Costa Rica are three hospitals which also act as referral centres for the different segments of the country. These include the San Juan de Dios Hospital, the Rafael Angel Calderon Guardia Hospital and the Mexico Hospital. Of significance and relevant to the case study is the San Juan de Dios Hospital which has radiotherapy facilities (International Atomic Energy Agency, 1998).
During the month of July 1997, the international atomic energy association received an invitation from the government of Costa Rica to aid in assessment of overexposure of radiotherapy. This overexposure had occurred to patients in San Jose Hospital in Costa Rica. The initiating occurrence specifically happened at San Juan de Dios hospital in San Jose on the 22nd of August, 1996. This was after a radioactive carbon source, 60 CO was replaced. When the new source was standardized, an inaccuracy was made in the computation of dose rate. Consequently, this error led to administration of considerable higher radiation doses compare to the prescribed intake in terms of exposure (International Atomic Energy Agency, 1998)....
e was no satisfactory explanation as to these large disparities in dose values, an expert was engaged to evaluate the possibilities of such differences. The expert was to assess the physical aspects of quality assurance in radiotherapy. Furthermore, the expert was also to verify degree of application recommended by the technical report series and those of compliance reports. The review was conducted between the 8th and 19th of July, 1996. Her report indicated that there were no records kept on the calibration of beams emitted by radiation machines. Additionally, the assessment showed that there was no information available on the specific equipment used to offer radiotherapy services. With working environment prevailing in tandem with dose determination procedures properly followed, the outcome obtained or the calculation of absorbed dose rate in a computer program was not easily verifiable. The computer program which was developed by the person in charge of dosimeter had errors of close to 5% in percentage dose values. Moreover, there was an error of approximately 2 centimeters in the optical distance indicator (Perez & Brady, 1998). Discrepancies of up to 8% within the calculated time found, for the same irradiation conditions, when a calculation method on the basis of percentage depth dose (PDD) and the tissue air ratio (TAR) was used. Initial examination indicated that similar absorbed dose rate value had been employed in both procedures. Consequently, revelation on confusion between the concepts of dose in air and dose in water at the depth of optimal maximization was eminent. Having underpinned and satisfactorily addressed these issues, the expert brought these findings to radiation oncologists at the hospital. These included thermo luminescence dosimeters dose