UNIVERSITY OF HONG KONG BACHELOR OF SCIENCE : FINAL EXAMINATION RADIOISOTOPE UNIT: (87102) RADIOISOTOPE TECHNIQUES IN PHYSICAL SCIENCE & TECHNOLOGY May 27, 1991 9:30a.m. - 11:30 a.m. (i) Answer 4 out of 5 questions. Question no. 1 (short answer questions) is compulsory. (ii) Question no. 1 carries 40 marks. Other questions carry 20 marks each. (iii) Candidates may use any self-contained, silent, battery-operated and pocket-sized calculator. The calculator should have numeral-display facilities only and should be used only for the purposes of calculation. lt is the candidate's responsibility to ensure that his calculator operates satisfactorily. (iv) Candidates must record the name and type of their calculators on the front page of their examination scripts. (Time allowed : 2 hours) 1. (A) What is the whole body dose equivalent limit in mSv yea( 1 for a designated worker as recommended by ICRP? (B) If the biological half-life of phosphorus in a system is 21 days and the radioactive half-life of 32 P is 14.3 days, what is the effective half-life? (C) After an acute dose of 20 mSv whole body radiation exposure, will there be likely any detectable clinical effects? (D) The mass energy absorption coefficient for 0.05 MeV photons is 0.161 cm 2 g· 1 in bone, compared with 0.043 cm 2 g· 1 in muscle. If the muscle dose in a bonejmuscle matrix is 100 JJGy, what will be the bone dose in JJGy?