Introduction to Health Physics: Fourth Edition - Ruang Baca FMIPA UB

TABLE 8-19. Summary of Dose Calculation Data for Example 8.6
RADIATION SAFETY GUIDES 393
TARGET m (kg) SOURCE DISINTEGRATIONS AF (T ← S) wT DOSE (Sv)
BBbas 4.3N4 BB1 604 0.0508 0.1665 3.256N9
BB2 16,956 0.0542
BBseq 1072 0.0985
AI 4,647,546 0
BBsec 8.6N4 BB1 604 0.216 0.1665 6.440N9
BB2 16,956 0.235
BBseq 1072 0.101
AI 4,647,546 0
bb 1.9N3 bb1 2399 0.157 0.333 6.641N9
bb2 15,788 0.165
bbseq 659 0.0962
AI 4,647,546 3.68N4
AI 1.1 AI 4,647,546 1 0.333 1.121N8
LNTH 0.015 LNTH 488,034 1 0.001 2.592N10
= 2.757N8
Note: N4 = 10 −4 .
Abbreviations: AF (T ← S), absorbed fraction (source to target); BB, bronchial; bb, bronchiolar; AI, alveolar-interstitial;
LNTH, lymph nodes (thoracic).
chemically with the tissue in the airway, or it may diffuse into bloodstream and be
absorbed into the body, or both processes may occur simultaneously. The biological
effects of an inhaled gas thus depend on its solubility and its chemical reactivity.
Accordingly, all gases are assigned to one of three classes: SR-0, SR-1, and SR-2.
Type SR-0 are gases of limited solubility and are nonreactive, such as H2, He, Ar,
Kr, and SF6. Such gases do not interact with the pulmonary tissues, and are not
significantly absorbed into the blood from the alveoli. It is reasonably assumed
that all the inhaled SR-0 gas is also exhaled. Radiation dose to the lungs is due
to the presence of the gas within the respiratory airways. The radiation hazard
from type SR-0 gas usually is from external radiation due to immersion in the
gaseous cloud. Radon is an inert gas, and would fall into this hazard category
if its progeny were not radioactive. The hazard from radon is not from the gas,
but from radon’s radioactive daughters. These radioactive descendents attach
themselves to atmospheric dust particles, as explained in Chapter 7, and these
dust particles are inhaled and deposited in the lungs.
Type SR-1 are gases that are either soluble or reactive or both, such as CO, NO2,
I2, CH3I, and Hg vapor. In the absence of specific data on the interaction of
the gas with the airway tissues, the HRTM assumes that all the inhaled gas is
deposited, with 10% in the ET1 region, 20% in ET2, 10% in BB, 20% in bb,
and 40% in the alveoli. From the alveoli, they may be absorbed into the blood
and transported to other organs and tissues where they may be metabolized or
deposited.
Type SR-2 gases are both highly soluble and reactive, such as HTO, SO2,H2S, HF,
and Cl2. These gases rapidly interact with the tissues in the upper respiratory tract