The unit rem ( r oentgen e quivalent for m an) is the product of the radiation d
ID: 993348 • Letter: T
Question
The unit rem (roentgen equivalent for man) is the product of the radiation dose in rads and the relative biological effectiveness (RBE) of radiation. The SI unit for effective dosage is the sievert (Sv) and 1 Sv = 100 rem. The table shown describes the biological effects of short-term radiation on humans. The intensity of radiation increases as you move closer to the radiation source according to the equation I1I2=d22d12 where d1 and d2 are the initial and final distances and I1 and I2 are the initial and final intensities.
1) At a distance of 33 ft , an ionizing radiation source delivers 4.0 rem of radiation. How close could you get to the source and still have no biological effects? Express your answer to two significant figures and include the appropriate units.
2.) A nurse administered 2.90 mL of a radioisotope solution that has an activity of 195 Ci/mL . What total dose of the radioisotope did the patient receive? Express your answer to three significant figures and include the appropriate units.
Intensity(rem) Biological effects 0-25 no detectable effects 25-100 temporary decrease in white blood cell count 100-200 nausea, vomiting, longer-term decrease in white blood cells 200-300 vomiting, diarrhea, loss of appetite, listlessness 300-600 vomiting, diarrhea, hemorrhaging, eventual death in some cases above 600 eventual death in nearly all cases
Explanation / Answer
1) At a distance of 33 ft , an ionizing radiation source delivers 4.0 rem of radiation. How close could you get to the source and still have no biological effects? Express your answer to two significant figures and include the appropriate units.
Solution :- d2 = 33 ft , d1 = ? , L1 = 4.0 rem , L2 = 25 rem
L 1 /L 2 = d1^2 / d2^2
4.0 / 25 = d1^2 /(33)^2
0.16 = d1^2/1089
1089*0.16 = d1^2
174.24 = d1^2
Taking square root of both sides we get
13.2 feet = d2
So the closest disntace that person can go is 13.2 feet.
2.) A nurse administered 2.90 mL of a radioisotope solution that has an activity of 195 Ci/mL . What total dose of the radioisotope did the patient receive? Express your answer to three significant figures and include the appropriate units
Solution :-
The total dose that patient receive = 195 uCi/ml * 2.90 ml = 566 uCi
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