Table 2.
Studies estimating tolerance dose 50 (TD50) of parotid glands using salivary scintigraphy
| Study (ref) | Number of patients (N) | Mean parotid dose | Salivary scintigraphy criteria for defining severe xerostomia | Tolerance Dose 50 (95% CI) | |
|---|---|---|---|---|---|
| 6 weeks-6 months | 1-year | ||||
| #Roesink [21] | 96 (conv) | 33.14Gy | SEF ratio <45% | 29Gy (25-34Gy) | 43Gy (37-51Gy) |
| Munter [26] | 18 (IMRT) | NR | SEF ratio <50% | 34.8Gy (27.6-42Gy) | NR |
| Munter [27] | 33 (conv) | 60.6Gy | SEF ratio <50% | 36.4Gy (20.5-42.3Gy) | NR |
| 19 (IMRT) | 27.7Gy | SEF ratio <50% | 35Gy (28-42Gy) | ||
| *Rudat [28] | 34 (conv) | 60.7Gy | SEF ratio <50% | NR | 51.1Gy (43.5-58.7Gy) |
| 31 (IMRT) | 30.9Gy | ||||
| Tenhunen [29] | 20 (IMRT) | 27.6Gy | SEF ratio <50% | 40.3Gy (30–53.6Gy) | 39.2Gy (27.9-50.2Gy) |
| Kapanen [30] | 25 (IMRT) | 23.2Gy | SEF ratio <50% | 30.4Gy (23.2-37.6Gy) | NR |
| Chen [31] | 31 (IMRT) | 51.7Gy IL | SEF ratio <45% | NR | 43.6Gy (41.3-45.9Gy) |
| 36.7Gy CL | |||||
| Present study | 41 (3D-CRT and IMRT) | 48.3Gy IL | SEF ratio <45% | 35.1Gy (23.6-42.6Gy) | 41.3Gy (34.6-48.8) |
| 39.7Gy CL | |||||
CI = confidence interval; SEF = salivary excretion fraction; conv = conventional; 3D-CRT = three dimensional conformal radiotherapy; IMRT = intensity modulated radiation therapy; NR = not reported; IL = ipsilateral; CL = contralateral.
#First report correlating salivary flow measurements with scintigraphic dataset; SEF ratio <45% best correlated with flow data becoming the benchmark scintigraphic criteria defining severe xerostomia.
*Updated results from previous publication (ref) reporting delayed xerostomia; conventional radiotherapy plus amifostine group has been excluded from these estimates.