Relative Deviation of PENTRAN from MCNP5
50-
40 -
~30
20-
0
- Bugle-96
-*- SCALES
+ CEPXS
30 60
Distance (cm)
Figure 2-10. Relative deviation of energy group 1 discrete ordinates results with Monte Carlo
results. Results using PENTRAN with BUGLE-96 were overall best in the water
phantom, and differences were within the Monte Carlo statistical uncertainty
2.4 Absorbed Dose Calculations
For the energy beam used in this study, the maximum electron range produced by the
primary photons is approximately 0.6 cm (as computed by the Tabata-Ito- Okabe (TIO) formula,
estimate for electron range, 41), which is less than the size of the smallest fine mesh used in the
water phantom. This allows electrons produced to deposit their energy within the fine mesh,
achieving CPE within the phantom volume. By applying this collisional kerma approximation
for absorbed dose computation based on the fluxes calculated using the SN method with
PENTRAN, we compared the SN based absorbed dose estimates with absorbed doses calculated
based on MCNP5 track length (F6) tallies, which estimate the energy deposited averaged over a
given cell volume and are equivalent to the collisional kerma, this is shown in Figure 2-11.