AbstractID: 9766 Title: New Approaches to PET and PET/CT Center Shielding Design
Purpose: New approaches to PET center shielding design may be required to keep personnel and public dosimetry levels within
recommended radiation protection guidelines. Newer shielding devices and strategically placed moveable shields may provide
substantial cost savings. Introduction: As PET and PET/CT centers achieve high throughput, certain issues become more important
for PET center shielding design. Should the patient be represented as a pseudo point source, allowing the use of 511 Kev (HVL = 4.0
mm-Pb) for the calculations? Using measured build-up factors or the broad beam HVL (5.5 mm-Pb), or some combination of these
may provide better agreement between calculated and measured dose rates. Similarly, which of the many exposure rate constants
reported in the literature should be used? In any design, model selection and assumptions affect the mix of fixed and moveable
shielding alternatives. Method: Measurements taken at operational PET and PET/CT centers show the protection provided by
alternate approaches to shielding design. Results: We present comparisons of radiation levels as measured when dosed patients are
shielded by strategically placed mobile or moveable shields, as compared to the use of structural shielding, with cost estimates for
remodeling and new construction. Conclusion: The HVL value used has a major impact upon the cost of construction for PET or
PET/CT centers. Initial data suggests that use of a higher effective HVL may be appropriate, and a combination of fixed, shadow and
moveable shields may minimize facility costs while achieving safe operation for high patient volumes.