<prompt> According to NCRP what is the maximum permissible radiation dose during pregnancy?0.5 rad5 rad15 rad50 rad  <response>: Ans. a 0.5 rad Ref. Christensens Physics of Diagnostic Radiology, 378The 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 individualRemmSv1Occupational exposures annualStochastic effects550 Non-stochastic effectsLens of eye15150 All other areas e.g., red marrow, breast, lung, gonads, skin, and extremities50500 Lifetime cumulative exposure1 x age in year10 x age in year2Public exposure annualEffective dose equivalent limit0.55 Dose equivalent limits for lens of eye, skin, and extremities5503Trainees under 18 years of ageEffective dose equivalent limit0.11 Dose equivalent limit for lens of eye, skin, and extremities5504Embryo-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 individuals 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 remyear, or 110th 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. 