Results for Effective Dose

Apron Thickness (mm lead equivalent) Estimate of//e = 1.5//w + 0.04// j Tube Voltage (kVp) Estimate of Relative to a Value of 1.0 

Using the approach of Webster, with the experimental findings for E (Faulkner and Marshall, 1993), one can produce an empirical formula for E that uses the results of monitoring devices worn under the apron at the waist and at the neck outside and above the apron, comparable to the formula developed for (Rosenstein and Webster, 1994). The formula and the values it yields relative to the E values measured by Faulkner and Marshall (1993) are presented in Table 3.7. 

The criteria for a desired formula for E for radiation protection purposes are (1) minimize the underestimates of E, even at the expense of larger overestimates of E for some conditions, and (2) obtain a close estimate of E at the combination most frequently encoimtered in clinical practice (i.e., 90 kVp, 0.5 mm lead equivalent apron and imdertable x-ray tube) (Rosenstein and Webster, 1994). 

The formula results in values between 1.06 and 1.96 E for 0.5 mm lead equivalent aprons and between 1.21 to 2.03 E for 0.3 mm lead equivalent aprons. Use of the formula is a simple and practical way to estimate E when both personal monitors are worn. 

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