Objective: To evaluate the five years average equivalent dose, the average collective equivalent dose and fatal cancer risk for the radiation workers in Radiology Department at Phramongkutklao Hospital.
Material and Method: In the Radiology Department at Phramongkutklao Hospital, occupationally exposed workers are measured by the Division of Radiation Protection Services, Department of Medical Sciences which measures radiation exposures and evaluated doses from external exposures. Individual’s doses of external exposure were monitored using film badges. The present study design describes a retrospective survey of occupational exposure in the Radiology Department at Phramongkutklao Hospital 2004-2008.
Results: The distribution of radiation workers monitored according to the groups in the years 2004-2008, physicist, technologist and assistant of technologist were the most numerous occupational group (51.13%). Nurse, assistant of nurse and nurse aids constituted 22.73%. About 59.73% of radiation workers in the Radiology Department at Phramongkutklao Hospital received an annual average equivalent dose below 0.02 mSν which defined as recording level and no radiation workers received doses above the International Commission on Radiological Protection (ICRP) Publication 60 recommended dose limit (20 mSν per year). The five years average equivalent dose per radiation worker was 1.098 mSν. Of all occupational groups measurably exposed, the nuclear medicine group received the highest of the five years average equivalent dose, collective equivalent dose and fatal cancer risk. The five years average equivalent dose, collective equivalent dose and fatal cancer risk for the physicist, technologist and assistant of technologist were the highest.
Conclusion: Total risk per the whole monitored radiation workers were 3.86 x 10-3 due to receive the five years average collective equivalent dose 0.096 man Sν. These values were estimated from a very small of number of radiation workers.

Keywords: Equivalent dose, Collective equivalent dose, Fatal cancer risk, Dose limit