Table 2.
Preshielding peripheral dose in the region of the thyroid gland, expressed as a percentage of the monitor units and as a percentage of the prescribed dose.
| Collimator size (mm) | Distance (cm) | Preshielding peripheral dose (cGy) | Preshielding peripheral dose (%MU) | Preshielding peripheral dose (%TD) | Monitor units | Prescribed dose (cGy) | Isodose line (%) |
|---|---|---|---|---|---|---|---|
| 12.5 | 20 | 5.00 | 0.12 | 0.25 | 4005 | 2000 | 84 |
| 10 | 20 | 6.48 | 0.12 | 0.32 | 5587 | 2000 | 75 |
| 20, 20, 20 | 22 | 15.22 | 0.13 | 0.76 | 11374 | 2000 | 75 |
| 5, 5, 5 | 20 | 23.01 | 0.13 | 1.15 | 18026 | 2000 | 75 |
| 7.5, 7.5, 15 | 16.5 | 35.38 | 0.17 | 1.97 | 20487 | 1800 | 79 |
| 10, 10, 15 | 14 | 164.90 | 0.69 | 6.60 | 23876 | 2500 | 75 |
| 20, 20, 20 | 14 | 40.55 | 0.16 | 1.62 | 25794 | 2500 | 67 |
| 5, 5, 5 | 18 | 59.43 | 0.22 | 3.30 | 27433 | 1800 | 76 |
| 7.5, 7.5, 15 | 19 | 35.73 | 0.13 | 1.99 | 28411 | 1800 | 75 |
| 7.5, 15, 25 | 14.5 | 132.15 | 0.33 | 5.29 | 39476 | 2500 | 70 |
MU: Monitor Units
TD: Prescribed Dose