Table 3.
Variation of pinnacle calculated dose with number of projections used.
| No. of Projections Used | Bladder Dose (cGy) | Prostate Dose (cGy) | Rectal Dose (cGy) |
|---|---|---|---|
| 2 | 2.2 | 1.7 | 1.4 |
| 3 | 3.4 | 2.6 | 2.0 |
| 4 | 4.5 | 3.4 | 2.7 |
| 5 | 5.6 | 4.3 | 3.4 |
| 6 | 6.7 | 5.1 | 4.1 |
| 7 | 7.9 | 6.0 | 4.8 |
| 9 | 10.1 | 7.7 | 6.2 |
| 11 | 12.4 | 9.5 | 7.6 |
| 14 | 15.8 | 12.1 | 9.7 |
| 21 | 23.5 | 17.9 | 14.3 |
| 41 | 45.9 | 35.0 | 28.0 |
| Portfilm a | 12.5 | 11.2 | 7.3 |
a
“Portfilm” doses were calculated using the protocol clinically used to acquire weekly portfilms at the clinic for prostate cases; 6 MU are used to acquire an AP projection and 8 MU are used to acquire the lateral projection, for a total of 14 MU per image set.