[Relation between uptake of 67Ga-citrate in salivary glands and irradiation doses]

A retrospective study is performed 67Ga-citrate uptake by scintigraphy to evaluate the relation between gallium uptake of salivary glands and radiotherapy with special reference to radiation dose and period after initial irradiation. Sixteen patients with radiotherapy to their head and neck regions were studied, undergone 67Ga scintigraphy for four times or more were investigated. The following results were obtained: 1. About half of the total number of salivary glands increased the uptake of 67Ga-citrate during radiotherapy. 2. The number of salivary glands which increased uptake in a group which received more than 30 Gy was greater than that in a group less than 30 Gy, and many of them remained with increased activity for one year after radiotherapy. 3. Uptake in glands that received dose less than 30 Gy showed rapid increasement initially, and showed decrease of uptake in six months after the irradiation. We concluded that there was different tendency of gallium uptake between a group of patient with irradiation of less than 30 Gy and that with irradiation of more than 30 Gy. It is suggested that we must always consider gallium uptake of salivary glands for long term after the radiotherapy, when we discuss the recurrence or metastases of neck lymph nodes of patients, who have performed radiotherapy to their head and neck regions, especially high dose irradiation.