[Radiometabolic therapy: dose equivalents from external exposure and internal contamination]. 1998

G Scielzo, and A Rivolta
Servizio di Fisica Sanitaria, Azienda Ospedaliera S. Giovanni Battista, Torino.

OBJECTIVE We describe our method for evaluating the dose received by external irradiation and internal contamination during radiometabolic therapy considering the daily activity at Ente Ospedaliero Ospedali Galliera, Genova, Italy. METHODS We used environmental and personal thermoluminescence dosimeters (LiF-100) and a whole-body counter system (WBC 6000 Harshaw) for direct activity measurements within the body after radionuclides administration. RESULTS Measurements were carried out both on workers allowed to access the restricted area and on people volunteering to assist non-self-sufficient patients. In the latter, we estimated the doses from activity measurements and using ICRP's radiometabolic models: more definite access to the treatment room and higher doses were the main reasons for a more accurate evaluation of volunteers than of workers. The combined study of 1-meter exposure immediately before the patient's discharge and both environmental and personal dosimetry on volunteers showed about the same value (50 microSv/hr) as mean exposure rate at 1 meter. Internal intake in workers showed similar contamination dose values. CONCLUSIONS These results, combined with the average working time of individual workers, permitted an a priori evaluation for different professional categories; the highest estimated value (< 75 microSv/month) for both irradiation and internal intake, is in agreement with the results of direct controls on workers. Therefore, we concluded that WBC controls should be carried out to verify the estimated doses. Routine monitoring is not useful because, I-131 half-life being very short, frequent periodic evaluations would turn out too expensive. Finally, these measurements would be affected by major errors because atypical ways of contamination do not permit to apply the strict protocols used in radiometabolic models.

UI MeSH Term Description Entries
D007457 Iodine Radioisotopes Unstable isotopes of iodine that decay or disintegrate emitting radiation. I atoms with atomic weights 117-139, except I 127, are radioactive iodine isotopes. Radioisotopes, Iodine
D007558 Italy A country in southern Europe, a peninsula extending into the central Mediterranean Sea, northeast of Tunisia. The capital is Rome. Sardinia
D011829 Radiation Dosage The amount of radiation energy that is deposited in a unit mass of material, such as tissues of plants or animal. In RADIOTHERAPY, radiation dosage is expressed in gray units (Gy). In RADIOLOGIC HEALTH, the dosage is expressed by the product of absorbed dose (Gy) and quality factor (a function of linear energy transfer), and is called radiation dose equivalent in sievert units (Sv). Sievert Units,Dosage, Radiation,Gray Units,Gy Radiation,Sv Radiation Dose Equivalent,Dosages, Radiation,Radiation Dosages,Units, Gray,Units, Sievert
D011834 Radiation Monitoring The observation, either continuously or at intervals, of the levels of radiation in a given area, generally for the purpose of assuring that they have not exceeded prescribed amounts or, in case of radiation already present in the area, assuring that the levels have returned to those meeting acceptable safety standards. Monitoring, Radiation
D011872 Radiology Department, Hospital Hospital department which is responsible for the administration and provision of x-ray diagnostic and therapeutic services. Hospital Radiology Department,X-Ray Departments,Department, Hospital Radiology,Department, X-Ray,Departments, Hospital Radiology,Departments, X-Ray,Radiology Departments, Hospital,X-Ray Department,Department, X Ray,Departments, X Ray,Hospital Radiology Departments,X Ray Department,X Ray Departments
D004781 Environmental Exposure The exposure to potentially harmful chemical, physical, or biological agents in the environment or to environmental factors that may include ionizing radiation, pathogenic organisms, or toxic chemicals. Exposure, Environmental,Environmental Exposures,Exposures, Environmental
D006801 Humans Members of the species Homo sapiens. Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D013819 Thermoluminescent Dosimetry The use of a device composed of thermoluminescent material for measuring exposure to IONIZING RADIATION. The thermoluminescent material emits light when heated. The amount of light emitted is proportional to the amount of ionizing radiation to which the material has been exposed. Dosimetries, Thermoluminescent,Dosimetry, Thermoluminescent,Thermoluminescent Dosimetries
D014915 Whole-Body Counting Measurement of radioactivity in the entire human body. Whole Body Counter,Whole-Body Counters,Body Counter, Whole,Body Counters, Whole,Counter, Whole Body,Counter, Whole-Body,Counters, Whole Body,Counters, Whole-Body,Counting, Whole-Body,Whole Body Counters,Whole Body Counting,Whole-Body Counter
D019047 Phantoms, Imaging Devices or objects in various imaging techniques used to visualize or enhance visualization by simulating conditions encountered in the procedure. Phantoms are used very often in procedures employing or measuring x-irradiation or radioactive material to evaluate performance. Phantoms often have properties similar to human tissue. Water demonstrates absorbing properties similar to normal tissue, hence water-filled phantoms are used to map radiation levels. Phantoms are used also as teaching aids to simulate real conditions with x-ray or ultrasonic machines. (From Iturralde, Dictionary and Handbook of Nuclear Medicine and Clinical Imaging, 1990) Phantoms, Radiographic,Phantoms, Radiologic,Radiographic Phantoms,Radiologic Phantoms,Phantom, Radiographic,Phantom, Radiologic,Radiographic Phantom,Radiologic Phantom,Imaging Phantom,Imaging Phantoms,Phantom, Imaging

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