Scintillation Counters
Since the development of the photoelectric tube and the photomultiplier tube (a combination of photoelectric cell and amplifier), the scintillation counter has become the most popular instrument for most purposes described in this booklet. The flash of light produced when an individual ionizing particle or ray strikes a sodium-iodide crystal is noted by a photoelectric cell. The intensity of the flash is a measure of the energy of the radiation, so the voltage of the output of the photomultiplier tube is a measure of the wavelength of the original gamma ray. The scintillation counter can observe up to a million counts per minute and discriminate sharply between gamma rays of different energies. With proper windows it can be used for alpha or beta counts as well.
Solid State Counters
The latest development is a tiny silicon (transistor-type) diode detector that can be made as small as a grain of sand and placed within the body with very little discomfort.
Scanners
Many of the applications described in this booklet require accurate knowledge of the exact location of the radioactive source within the body. Commonly a detecting tube is used having a collimating shield so that it accepts only that radiation that strikes it head-on. A motor-driven carrier moves the counter linearly at a slow rate. Radiation is counted and whenever the count reaches the predetermined amount—from one count to many—an electric impulse causes a synchronously moving pen to make a dot on a chart. The scanner, upon reaching the end of a line moves down to the next line and starts over, eventually producing a complete record of the radiation sources it has passed over.
SUGGESTED REFERENCES
Technical Books
Radioactive Isotopes in Medicine and Biology, Solomon Silver, Lea & Febiger, Philadelphia, Pennsylvania 19106, 1962, 347 pp., $8.00.
Atomic Medicine, Charles F. Behrens and E. Richard King (Eds.), The Williams & Wilkins Company, Baltimore, Maryland 21202, 1964, 766 pp., $18.00.
The Practice of Nuclear Medicine, William H. Blahd, Franz K. Bauer, and Benedict Cassen, Charles C. Thomas, Publisher, Springfield, Illinois 62703, 1958, 432 pp., $12.50.
Progress in Atomic Medicine, John H. Lawrence (Ed.), Grune & Stratton, Inc., New York 10016, 1965, volume 1, 240 pp., $9.75.
Radiation Biology and Medicine, Walter D. Claus (Ed.), Addison-Wesley Publishing Company, Reading, Massachusetts 01867, 1958, 944 pp., $17.50. Part 7, Medical Uses of Atomic Radiation, pp. 471-589.
Radioisotopes and Radiation, John H. Lawrence, Bernard Manowitz, and Benjamin S. Loeb, McGraw-Hill Book Company, New York 10036, 1964, 131 pp., $18.00. Chapter 1, Medical Diagnosis and Research, pp. 5-45; Chapter 2, Medical Therapy, pp. 49-62.