What is According to NCRP what is the maximum permissible radiation dose during pregnancy? and explain in detail?
Ans. a (0.5 rad) (Ref. Christensen's Physics of Diagnostic Radiology, 378)The NCRP recommends a total dose equivalent limit (excluding medical exposure) of 0.5 rem (50 mSv) for the embryo, fetus. Once a pregnancy becomes known, exposure of the embryo-fetus should be no greater than 0.05 rem (0.5 mSv) in any month (excluding medical exposure).NCRP Recommendation of Radiation Dose LimitsClass of exposed individualRemmSv1)Occupational exposures (annual)Stochastic effects550 Non-stochastic effectsLens of eye15150 All other areas (e.g., red marrow, breast, lung, gonads, skin, and extremities)50500 Lifetime cumulative exposure1 (x age in year)10 (x age in year)2)Public exposure (annual)Effective dose equivalent limit0.55 Dose equivalent limits for lens of eye, skin, and extremities5503)Trainees under 18 years of ageEffective dose equivalent limit0.11 Dose equivalent limit for lens of eye, skin, and extremities5504)Embryo-fetus exposures Total dose equivalent limit0.55 Dose equivalent limit in a month0.050.5# Excluding background and medical exposures, but including both internal and external exposures# Rem = rads x quality factor (R)# Because the quality factor for X-rays is 1, hence rad = rem# In fact at diagnostic energy level the rad, rem and roentgen usually will be considered.According to NCRP an individual's lifetime effective dose equivalent in rem should not exceed the value of his or her age in years.According to NCRP the dose limit for the occasionally exposed individual is 0.5 rem/year, or 1/10th of MPD for the occasionally exposed.The NCRP recommends a total dose equivalent limit of 0.5 rem (50 mSv) for embryo fetus during pregnancy.