Biomedical subjects
Publications and source records attributed to H Dawalibi.
FORTRAN IV algorithms are presented for calculating the modulation transfer function, the phase transfer function, the modulation transfer function area, an information transfer function, and the optimum frequency response as well as plotting the curves for these matrices. An important feature of the programs is an editing routine.
A simple mathematical algorithm is derived from experimental data for dose rates from 137Cs sources in a finite tissue equivalent medium corresponding to the female pelvis. An analytical expression for a point source of 137Cs along with a simple numerical integration routine allows for rapid as well as accurate dose rate calculations at points of interest for gynecologic insertions. When compared with theoretical models assuming an infinite unit density medium, the measured dose rates are found to be systematically lower at distances away from a single source; 5 per cent at 2 cm and 10 per cent at 7 cm along the transverse axis. Allowance in the program for print out of dose rates from individual sources to a given point and the feature of source strength modification allows for optimization in terms of increasing the difference in dose rate between reference treatment points and sensitive structures such as the bladder, rectum and colon.
An algorithm utilizing a two-dimensional polynomial power functions least squares fit has been applied to the calculations of TAR in the case of CO-60 teletherapy and TMR in the case of an 8MV LS75/10 linear accelerator giving less than +/- 1/2% errors respectively between calculated and measured values. The TAR and TMR algorithms are used as subroutines in pocket sized and table top programmable calculators or computers and thus provide rapid calculation of treatment time or monitor units as well as given dose.