The Dependency of the Volume Activity of I-131 in a Hospital Sewage Treatment Plant on the Amount of I-131 Used as a Medical Treatment in the Nuclear Medicine Ward

The subject of the work is radiation protection at a nuclear medicine workplace with a bed section in connection with the therapy of thyroid gland diseases using radioisotope 131I. In the theoretical part, the work briefly deals with the anatomy and pathology of the thyroid gland and ways of therapy, and outlines the basic characteristics of radioisotope 131I and history of nuclear medicine and radiation protection. In the practical part, there is a verification of the efficiency of radiation protection when handling liquid waste and a verification of the correlation of the activity of liquid waste with the activity of radiopharmaceutical administered. The malignant tumours of the thyroid gland constitute 0,5?1 % of all tumoral diseases. Some types of this tumour, which are histologically differentiated, retain the capability of extracting iodine from blood and are thus suitable for being treated using iodine radioisitope. That's why these types of tumour are treated most frequently at nuclear medicine departments. The basis of therapy is the surgical removal of tumoral tissue, usually of the whole thyroid gland, and administration of radioisotope 131I. When treating the thyroid gland, the patient is always hospitalized at a nuclear medicine department with a bed section. Radioisotope 131I is mixed ? and ? emitter and after being administred to a patient, it is the source of radiation danger for hospital personnel, possibly for others individuals. At the same time it is excreted from the organism by urine, stool and sweat. On that score due attention must be paid to safety measures. In view of the magnitude of this problem and the emphasis that is currently laid to protection against ionizing radiation, I chose this issue as a subject of my bachelor's work. The goal of the practical part of the work was to verify whether the limits set by Decree No. 307/2002 Coll., as amended by Decree No. 499/2005 Coll. on radiation protection were observed under the current system of handling liquid waste in the bed section of the Nuclear Medicine Department of the České Budějovice Hospital. Two hypotheses were set: Operation regulations and current programme equipment of the technical installations for the automatic draining of waste water from the bed section of the Nuclear Medicine Department are sufficient for the limits set by Decree not being exceeded; the other hypothesis assumes that the values of the volume activity of waste water in the drainage tank of the hospital's sewage plant conform to the activity of a radiopharmaceutical administered to patients treated at the Nuclear Medicine Department of the České Budějovice Hospital. For the purposes of this work, the activity of waste in the drainage tank of the hospital's sewage plant was measured with a well detector once a week for a period of two month to verify that the activity does not exceed a release level of 455 Bql-1 set in an addendum to Decree No. 307/2002 Coll. It was ascertained by measuring that the average activity of waste in the watched period was 279,8 Bql-1, the highest activity measured on March 18, 2013 being 373 Bql-1. In the watched period, the release activity set by the law was not exceeded in any week. At the same time, the correlation of the values of radioactivity administered with the radioactivity of waste water was proved. Consequently, both hypotheses of the work were proved. The work proved that the limits set by Decree No. 307/2002 Coll., as amended by Decree No. 499/2005 Coll. on radiation protection, were observed under the current system of handling liquid waste in the bed section of the Nuclear Medicine Department of the České Budějovice Hospital