Howard A. Swartz
and Paul R. Quinney College of Pharmacy Butler University Indianapolis, Indiana
Radiography of Animal Tissue
I
Radioisotopes have been widely employed as radiation sources in industrial radiography and in recent years have been introduced into medical radiography. More than 30 isotopes have been reported, including En-155, Am-241, Xe-133, Fo55, Cs-137, Co-60, Au-195, Hf-175, Pm-147, Sm-145, Ir-192, and I-125.1,2 Gamma sources have found the widest application in industry, but the introduction of beta bremsstrahlung sources is of considerable interest.= I n medical radiography the low energy gamma are of prime interest, as they afford excellent film contrast, definition, and sharpness with a very low radiation air/ tissue dose. There is a continuing need for compact, light, and safe radiographic sources and equipment which can serve as a supplement to conventional X-ray equipment. In addition, although X-ray devices satisfy most industrial and medical applications, isotope sources do offer some distinct advantages in that they are portable, require no power source, and are applicable to inside-out and 4 a radiography. Portable isotope radiation sources are ideal for applications in emergency and civil defense sit.uations, zoos, veterinary
' PRESSLY, R.S., 1801opes Radiation, 1 (2) 174 (1963). ' GRUYERMIN,I. J., AND SCHIYLEY, J. K., Nuc~o&S,
work, and field hospitals. Applications in these areas can be readily illustrated with extremely low levels of activity as described in this report using a source of 1-125. P~ocedure: 1-125 has a half-life of 57.4 days and decays to Te-125 by electron capture, producing K X-rays of about 27 Kev and L X-rays of about 4 Kev. I n addition, gamma rays of 35 Kev are produced in about 7% of the disintegrations. I n radiography, the gamma are of principle interest and the X-rays are readily absorbed or filtered by source covering or containers. Two millicuries of 1-125 as NaI in 0.2 ml of an aqueous thiosulphate solution contained in a 10 ml glass vial was positioned in the apex of a in. lead
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Figure 2.
Radiography of o Beon and A Frog.
cone. The height and diameter of the cone is not critical and will depend on the size of the specimen involved. In this instance, the opening of the cone covered an 8 X 10 in. sheet of Kodak EK No Screen Ready-Pack X-ray film. The height was sufficient t o allow a t least 6 in. between the source and the specimen positioned on the film pack. The dimensions are illustrated in Figure l. The specimen was exposed for 40 min; the film was removed and developed. The ready-pack film allows exposure of the specimen in a lighted room. Results: The results obtained from the radiography of a froe, a bean ~ o d and . a mouse are illustrated in Figures 2 a n d 3. ~ h e k eshorn clearly the application of
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Figure 3.
Rodiogrophy of a Moure.
isotope radiation sources as substitutes for X-rays in the film visualization of body structures. The radiographs obtained show good contrast, definition, sharpness, and low magnification. Similar results could he obtained with shorter exposure times by using higher levels of activity, preparing a special source of the isotope to reduce mass absorption losses by the glass vial, or by reducing the distance between the source and the specimen. The radiation dose was very low, and with the source employed a t a distance of 6 in., the air/tissue dose was 2.4 mr/hr, or for 40 min a total dose of 1.6 mr. This technique should find wide application in medical radiography and in the teaching and study of anatomy.
