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. 2012 Oct;85(1018):1415-9.
doi: 10.1259/bjr/30678306. Epub 2012 May 9.

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

A Fiorentino  1 , R Caivano, V Metallo, C Chiumento, M Cozzolino, G Califano, S Clemente, P Pedicini, V Fusco
Affiliations

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

A Fiorentino et al. Br J Radiol. 2012 Oct.

Abstract

Objective: To evaluate volumetric changes of parotid glands (PGs) during intensity-modulated radiotherapy (IMRT) in head and neck cancer patients.

Methods: 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.

Results: 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%.

Conclusion: 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.

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Figures

Figure 1
Figure 1
An axial slice showing the right parotid gland on the (a) planning CT and on the (b) last cone-beam CT.
Figure 2
Figure 2
Average volumetric variation in ipsilateral parotid glands. CBCT, cone-beam CT.
Figure 3
Figure 3
Average volumetric variation in contralateral parotid glands. CBCT, cone-beam CT.
Figure 4
Figure 4
Average volumetric variation in both parotid glands. CBCT, cone-beam CT.
See this image and copyright information in PMC

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