Parotid gland volumetric changes during intensity-modulated radiotherapy in head and neck cancer

• Published in: British journal of radiology Vol. 85; no. 1018; pp. 1415 - 1419
• Main Authors: FIORENTINO, A, CAIVANO, R, METALLO, V, CHIUMENTO, C, COZZOLINO, M, CALIFANO, G, CLEMENTE, S, PEDICINI, P, FUSCO, V
• Format: Journal Article
• Language: English
• Published: London British Institute of Radiology 01-10-2012; The British Institute of Radiology
• Subjects: Adult; Aged; Biological and medical sciences; Cone-Beam Computed Tomography; Female; Head and Neck Neoplasms - radiotherapy; Humans; Investigative techniques, diagnostic techniques (general aspects); Male; Medical sciences; Middle Aged; Organ Size; Organ Sparing Treatments - methods; Otorhinolaryngology (head neck, general aspects and miscellaneous); Otorhinolaryngology. Stomatology; Parotid Gland - anatomy & histology; Parotid Gland - diagnostic imaging; Parotid Gland - radiation effects; Prospective Studies; Radiotherapy Dosage; Radiotherapy, Intensity-Modulated - methods; Retrospective Studies; Tumors; Nuclear medicine; Volumetric analysis; Intensity modulated radiotherapy; Treatment; Parotid gland; Digestive system; Radiology; Salivary gland; ENT disease; Head and neck cancer; Malignant tumor; Cancer
• ISSN: 0007-1285; 1748-880X
• DOI: 10.1259/bjr/30678306

To evaluate volumetric changes of parotid glands (PGs) during intensity-modulated radiotherapy (IMRT) in head and neck cancer patients.
During IMRT all patients underwent kilovolt cone-beam CT (CBCT) scans to verify the set-up positioning in a protocol study. On each CBCT scan, the PGs were retrospectively contoured and evaluated with a dose-volume histogram.
From February to June 2011, 10 patients were enrolled. 140 CBCT scans were registered (280 PGs): for each patient, a median of 14 CBCT scans were performed (range 14-16). At the start of radiation, the average volume for ipsilateral PGs (iPGs) was 18.77 ml (range 12.9-31.2 ml), whereas for contralateral PGs (cPGs) it was 16.63 ml (range 8.3-28.7 ml). At the last CBCT scan, the average volume loss was 43.5% and 44.0% for the iPG and cPG, respectively. When we analysed the percentage of volume loss, we observed that the volume decreased by linear regression (r(2)=0.92 for iPG; r(2)=0.91 for cPG), with an average volume loss rate of 1.5% per day for both PGs. During the third week of treatment the volume of both PGs reduced by 24-30%.
Our data show that, during IMRT, the shrinkage of PGs should be taken into account. A replan could be indicated in the third week of radiotherapy.