The detection and measurement of radiation is based on the interaction of radiations with matter discussed in Chap. 1. In gases, ionizing radiations, particulate or electromagnetic, interact with gas molecules to produce positive and negative ions, which are then collected as current or count by the application of a voltage. The amount of ionization is proportional to the amount of energy deposited by the radiation. At low voltages, the ionization is measured as current that is proportional to the amount of radiation. Dose calibrators, pocket dosimeters, and ionization chambers operate on this principle at low voltages (∼ 150 V). At high voltages (∼ 900 V), ions are multiplied in an avalanche of interactions producing a pulse that is independent of the energy and type of radiation. Each event of interaction is detected as a count, and this principle is applied in Geiger–Müller (GM) counters, which are used as radiation survey meters.
KeywordsAttenuation Cadmium Tungsten Radionuclide Bismuth
References and Suggested Reading
- Blodgett et al,(2007).Blodgett TM, Meltzer CC, Townsend DW (2007). PET/CT: Form and function. Radiology 242:360Google Scholar
- Bushberg et al,(2002).Bushberg JT, Seibert JA, Leidholdt Sr EM, Boone JM (2002). The essential physics of medical imaging, 2nd ed. Lippincott, Williams and Wilkins, PhiladelphiaGoogle Scholar
- Chatziioannou et al,(1999).
- Cherry and Dahlbom(2004).Cherry SR, Dahlbom M (2004). PET; Physics, instrumentation, and scanners. In: Phelps ME (ed) PET; Molecular imaging and its biological applications. Springer, New YorkGoogle Scholar
- Cutler et al,(1992).
- Cherry et al,(2003).Cherry SR, Sorensen JA, Phelps ME (2003). Physics in nuclear medicine, 3rd ed. W.B. Saunders, PhiladelphiaGoogle Scholar
- Larobina et al,(2006).
- Melcher, (2000).
- Patton(2002).Patton JA (2002). Physics of PET. In: Delbeke D, Martin WH, Patton JA, Sandler MP (eds) Practical FDG imaging. Springer, New YorkGoogle Scholar
- Turkington(2001).Turkington TG (2001). Introduction to PET instrumentation. J Nucl Med Technol 29(1):89Google Scholar