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It was with great interest I read the review by Cheng et al  about the assessment of salivary glands after radiotherapy. Owing to its widespread availability and low cost, CT is the most frequently used imaging procedure in the staging and post-therapeutic follow-up of head and neck tumours. As described by the authors there are surprisingly few reports on radiation induced changes of the salivary glands on CT. Regarding this topic I would like to add further data, which we presented at last year’s meeting of the German Radiological Society (DRG) . We retrospectively studied the changes in density and volume of the submandibular gland in pre- and post-therapeutic examinations in a small sample of patients (10 male patients, mean age 46 years, primary radiochemotherapy of a histological proven squamous cell carcinoma of the hypopharynx with fractionated radiation of 55–65 Gy and 5 FU/ cisplatin, imaging after application of 120 ml of iodinised constrast media intravenously). The density of the submandibular gland showed a time-dependent course. First there was an increase in the median density of approximately 19% in the first post- therapeutic examination (1–2 months after final of radiotherapy treatment). The median density than showed a minimal decrease of 5% compared with the pre-therapeutic examination 4–6 months after the final radiotherapy treatment and a strong decrease in median density of 55% in examinations over 1 year after cessation of the radiotherapy. Bronstein et al  also reported an increase in the density of salivary glands after radiotherapy, but they performed only one post-therapeutic scan per patient, so a time-dependent change could not be assessed . We believe that these time-dependent changes are in accordance with the timing of pathological changes with acute inflammatory reaction followed by progressive fibrotic changes . Despite the preliminary nature of this data radiologists should be aware of these time-dependent density changes when examining post-treatment head and neck CT scans.