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Table 2 Studies estimating tolerance dose 50 (TD50) of parotid glands using salivary scintigraphy

From: Prospective longitudinal assessment of parotid gland function using dynamic quantitative pertechnate scintigraphy and estimation of dose–response relationship of parotid-sparing radiotherapy in head-neck cancers

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

  1. 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.
  2. #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.
  3. *Updated results from previous publication (ref) reporting delayed xerostomia; conventional radiotherapy plus amifostine group has been excluded from these estimates.