Syntax:
DECAY: RHL={characteristic decay constant of the radioisotope (h)}
Example:
DECAY: RHL=1443.36 !I-125 (h)
DECAY: RHL=407.04 !Pd-103 (h) NOTE: Refer to the table of selected radioisotope half-lives.
Purpose: Set the half-life of the radioactive source. The half-life determines the rate at which the instantaneous absorbed dose rate near the source decreases as a function of time (see also the LAM parameter).
Data Type: real
Unit: hour
Default: ~ 10308 h (machine infinity; effectively infinite half-life)
Comments: The TCUT and DCUT parameters are used to limit damage repair simulations of damage repair processes to a finite time period. This procedure is justifiable on the grounds that, at some point in time, the activity of the radiation source becomes so small that any further radiation killing of the cell population can be neglected. Repopulation effects may also suffice to compensate for any radiation killing (i.e., the surviving fraction remains constant). The TAD parameter represents the total absorbed dose delivered to the cell system over all time. The SAD parameter is the effective dose delivered to the cell system in a finite time interval (0, TCUT). The total delivered dose is related to the effective delivered dose by SAD=(1-DCUT)*TAD.
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