ABSTRACT
Background: Annual patient effective dose equivalent can be considered as a quantitative physical parameter describing the activities performed in each nuclear medicine department. Annual staff dose equivalent could be also considered as a parameter describing the amount of radiation risk for performing the activities. We calculated the staff to patient dose equivalent ratio to be used as a physical parameter for quantification of ALARA law in nuclear medicine departments
Materials and Methods: As a part of nationwide study, this paper reports the staff and patient absorbed dose equivalents from diagnostic nuclear medicine examinations performed in four nuclear medicine departments during 1999-2002. The type and frequency of examinations in each department were determined directly from hospital medical reports. Staff absorbed dose equivalents were calculated from regular personal dosimeter reports
Results: The total number of examinations increased by 16.7% during these years. Annual patient collective dose equivalent [EDE] increased about 13.0% and the mean effective dose equivalent per exam was 3.61+/-0.07 mSv. Annual total staff absorbed dose equivalent [total of 24 radiation workers] in four departments increased from 40.45 mSv to 47.81 mSv during four years that indicates an increase of about 20.6%. The average of annual ratios of staff to patient effective dose equivalents in four departments were 1.83×10[-3], 1.04×10[-3], 3.28×10[-3] and 3.24×10[-3], respectively, within a range of 0.9×10[-3] - 4.17×10[-3]. The mean value of ratios in four years was about 2.24×10[-3] +/- 1.09×10[-3] that indicates the staff dose of about two 1000[th] of patient dose
Conclusion: The mean value of ratios in four years was about 1.89×10[-3] +/- 0.95×10[-3] indicating the staff dose of about one 1000th of the patient dose. The staff to patient absorbed dose equivalent ratio could be used as a quantitative parameter for describing ALARA law in radiation protection and risk-benefit assessments