Quantitative radionuclide sialography in the diagnosis of salivary function following head and neck irradiation

ABSTRACT

Quantitative 99m Tc-pertechentate sialography with citric acid stimulation was performed in 48 patients with head and neck cancer for studying early and delayed effects of irradiation on salivary glands. The shape of the time activity curves was classified into 4 grades according to the degree of radiation induced dysfunction. A ratio of pre and post stimulation count [Rc] was applied in major glands in relation to different radiation doses and volume of the glands included in the field of treatment. The low radiation dose of 20 Gy led to rise in Rc's specially in partial salivary gland irradiation. Higher doses of 30 and 40 Gy led to gradual diminution to reach a remarkable decrease at dose level of 50-60Gy. Radiation changes were more evident in parotids than submandibular at intervals < 2-6 months and in dose range of 30-40 Gy. A dose ranging from 50 to 60 Gy led to maximum impairment in both glands at interval of 12 months. Partial recovery occurred in partial volume irradiation at interval ranging from 36 to 60 months