ESTRO 2025 - Abstract Book

S932

Clinical – Head & neck

ESTRO 2025

investigate the effect of submandibular sparing. Hence we conducted a study to analyse the functional changes in the submandibular glands relative to the radiation dose using dynamic quantitative pertechnetate scintigraphy. Our study is distinctive for its detailed scintigraphic analysis of the less studied submandibular gland and its longitudinal evaluation of patients with spared and non-spared submandibular glands. Material/Methods: Eligible participants included adults with histologically confirmed squamous cell carcinoma of the head and neck, no distant metastases, an ECOG PS of 0-2, and planned for radical radiation using volumetric modulated arc radiotherapy. An intravenous injection of 8-10 mCi of Technetium-99m sodium pertechnetate was administered, followed by dynamic imaging of the parotid and submandibular glands and upper thyroid 10 seconds later using a Symbia T6 gamma camera. After 15 minutes, 2 mL of lemon juice was provided to stimulate salivary secretion, and imaging was repeated. Scintigraphy was performed at baseline 3, 6 and 12 months after radiation. Umax was our primary objective as it reflects normal salivary gland function, with higher counts indicating better function.

Results: At baseline, the median (IQR) Umax was 81.0 (57.0–100.7) and 76.9 (59.7–112.7) for the spared and non-spared glands (p=0.97). Three months post-radiation, Umax decreased in both groups, median of 65.0 (47.7-90.9) in the spared group and 69.5 (53.1-111.3) in the non-spared group (p=0.4). At six months, Umax declined further to 62.9 (53.4-98.0) and 63.7(45.1-82.0) respectively (p=0.24). By 12 months, the spared group showed substantial recovery, reaching a median Umax of 75.6( 56.1-111.3) while the Umax declined further in the non-spared group to 51.1(40.4 76.5)(p=0.002). The Umax, SEF rSEF and SEF ratios are given below. We had no recurrences in the spared region.