- If 1 mCi of a radionuclide is adequately shielded by 5 HVLs of a shield-
ing material, how many HVLs are needed to provide equal shielding
for (a) 5 mCi and (b) 8 mCi? - A 1-mm lead apron will afford approximately twice as much protection
as a 0.5-mm apron, or does this shielding depend on the energy of the
radiation? - How many HVLs are approximately equivalent to three tenth-value
layers? - Suppose 5% of the 364-keV photons of^131 I are transmitted after passing
through a lead brick of 10-cm thickness. Calculate the HVL of lead for
(^131) I.
- There is a 75% chance that a monoenergetic photon beam will be atten-
uated by 4 mm of lead. What is the HVL of lead for the photon? - Which of the following radiations has the highest LET?
(a) 120-keV x-ray
(b) 100-keV electron
(c) 5-MeV a-particle
(d) 10-MeV proton
(e) 14-MeV neutron
Suggested Readings
Cherry SR, Sorensen JA, Philips ME.Physics in Nuclear Medicine. 3rd ed.
Philadelphia: W.B. Saunders; 2003.
Friedlander G, Kennedy JW, Miller JM.Nuclear and Radiochemistry. 3rd ed. New
York: Wiley; 1981.
Johns HE, Cunningham JR.The Physics of Radiology. 4th ed. Springfield, Ill:
Charles C Thomas; 1983.
Knoll GF.Radiation Protection and Measurement.3rd ed. New York: Wiley; 2003.
Lapp RE, Andrews HL.Nuclear Radiation Physics. 4th ed. Englewood Cliffs, NJ:
Prentice-Hall; 1972.
70 6. Interaction of Radiation with Matter