No abstract

No abstract

No abstract

Dose distributions from point y-ray sources within bound and unbound tissue-like absorbers were obtained by means of Monte Carlo calculations. Results are presented for source energies ranging from 30 to 2i50 kev. These results are compared with approximate dose distributions utilizing an " effective " absorbtion coefficient and with moment method calculations of the dose distribution within an infinite water phantom. Boundary effect's were evaluated by comparing the dose in spheres of radii 10, 20, 30 and 40 cm with the dose in an unbounded absorber. I n some cases, the introduction of a non-reflecting boundary reduces the dose a t the boundary by nearly a factor of two. However, boundary effects are shown to be unimportant a t distances greater than one mean free path from non-reflecting interface.