The influence of saliva flow stimulation on the absorbed radiation dose to the salivary glands during radioiodine therapy of thyroid cancer using super(124)I PET(/CT) imaging

• Published in: European journal of nuclear medicine and molecular imaging 2010-12, Vol.37 (12), p.2298-2306
• Main Authors: Jentzen, Walter, Balschuweit, Dorothee, Schmitz, Jochen, Freudenberg, Lutz, Eising, Ernst, Hilbel, Thomas, Bockisch, Andreas, Stahl, Alexander
• Format: Article
• Language: English
• Subjects: Chewing; Citrus limon; Computed tomography; Data processing; Dosimetry; Food; Fruit juices; Kinetics; Nuclear medicine; Parotid gland; Radiation; Saliva; Salivary gland; Side effects; Statistical analysis; Submandibular gland; thyroid cancer
• ISSN: 1619-7070; 1619-7089
• DOI: 10.1007/s00259-010-1532-z

Purpose: A serious side effect of high-activity radioiodine therapy in the treatment of differentiated thyroid cancer is radiogenic salivary gland damage. This damage may be diminished by lemon-juice-induced saliva flow immediately after super(131)I administration. The aim of this study was to assess the effect of chewing lemon slices on the absorbed (radiation) doses to the salivary glands. Methods: Ten patients received (pretherapy) super(124)I PET(/CT) dosimetry before their first radioiodine therapy. The patients underwent a series of six PET scans at 0.5, 1, 2, 4, 48 and greater than or equal to 96h and one PET/CT scan at 24h after administration of 27MBq super(124)I. Blood samples were also collected at about 2, 4, 24, 48, and 96h. Contrary to the standard radioiodine therapy protocol, the patients were not stimulated with lemon juice. Specifically, the patients chewed no lemon slices during the pretherapy procedure and neither ate food nor drank fluids until after completion of the last PET scan on the first day. Organ absorbed doses per administered super(131)I activity (ODpAs) as well as gland and blood uptake curves were determined and compared with published data from a control patient group, i.e. stimulated per the standard radioiodine therapy protocol. The calculations for both groups used the same methodology. Results: A within-group comparison showed that the mean ODpA for the submandibular glands was not significantly different from that for the parotid glands. An intergroup comparison showed that the mean ODpA in the nonstimulation group averaged over both gland types was reduced by 28% compared to the mean ODpA in the stimulation group (p=0.01). Within each gland type, the mean ODpA reductions in the nonstimulation group were statistically significant for the parotid glands (p=0.03) but not for the submandibular glands (p=0.23). The observed ODpAs were higher in the stimulation group because of increased initial gland uptake rather than group differences in blood kinetics. Conclusion: The super(124)I PET(/CT) salivary gland dosimetry indicated that lemon juice stimulation shortly after super(131)I administration in radioiodine therapy increases the absorbed doses to the salivary glands.