. Biophysics: concepts and mechanisms. Biophysics. (several feet) Depth in tissue Figure 5-9. Penetration of 1 Mev Alphas, Betas, Gammas, and Neutrons into tissue In simplest cases, the curve for gammas is truly exponential; that for betas has less curvature and reaches a maximum value, which is the depth of penetration of the fastest betas. Note that the area under each curve corre- sponds to 100 per cent of the impinging rays hitting the target. The depth of penetration is radically different for the three cases. TABLE 5-3. Ranges of Various Types of Radiation in Soft Tissue.* Range of Radia
. Biophysics: concepts and mechanisms. Biophysics. (several feet) Depth in tissue Figure 5-9. Penetration of 1 Mev Alphas, Betas, Gammas, and Neutrons into tissue In simplest cases, the curve for gammas is truly exponential; that for betas has less curvature and reaches a maximum value, which is the depth of penetration of the fastest betas. Note that the area under each curve corre- sponds to 100 per cent of the impinging rays hitting the target. The depth of penetration is radically different for the three cases. TABLE 5-3. Ranges of Various Types of Radiation in Soft Tissue.* Range of Radiation in Material Usual Ionizing of Low Atomic Number Radiation Energy Range (mev) Particles in Tissue Actual Range in Air, NTP (cm) Equiv. Range in Watery Tissue (cm) Beta rays to 5 electrons to 1000 to Electron beams 2 to 10 electrons 300 to 8000 to 10 X rays and electrons 230 Gamma electrons 25,000 rays** electrons 23,000 10 L 10 electrons 34,000 34 Fast neutrons** to 10 protons many meters ~10 Slow less than (protons) neutrons*** lOOev protons + 400 (electrons) gammas Proton beamsj 5 to 400 protons 30 to 80,000 to 80 Alpha raysf 5 to 10 alphas 4 to 14 to *Krom "Radiological Health] [andbook," National Bureau of Standards Wa hington, D. C, I960 **Range for absorption of half the incident radiation. ***From "Safe Handling of Radioisotopes," Health Physics Addendum," < G Vppleton and I' N Krishnamoorthy. Eds., International Atomic Energy Agency, Vienna, I960 +From G. J. Hine and G. L. Brownell. "Radiation Dosimetry," Academii Press, [n< 1956 and W Whaling, "The Energy Loss of Charged Particles in Mattel " Handbuch der Physik, XXXI\. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble
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