Cone-beam computed tomography dose monitoring during intensity-modulated radiotherapy in head and neck cancer: parotid glands.
OBJECTIVE
To evaluate the dosimetric changes of parotid glands (PG) during a course of intensity-modulated radiotherapy (IMRT) in head and neck (H&N) cancer patients.


METHODS
Ten patients with H&N cancer treated by IMRT were analyzed. The original treatment plan (CT(plan)) was transferred to cone-beam computed tomography (CBCT) acquired at the 15th and 20th treatment day (CBCT(plan) I and II, respectively). The PG mean dose (D(mean)), the dose to 50 % of the volume, and the percent of volume receiving 30 and 50 Gy were measured by the dose volume histogram.


RESULTS
30 IMRT plans were evaluated (3 plans/patient). All dosimetric end points increased significantly for both PG only when CT(plan) was compared to CBCT(plan) I. The D(mean) increased significantly only for ipsilateral PG (p = 0.02) at week 3.


CONCLUSIONS
During a course of IMRT, CBCT is a feasible method to check the PG dosimetric variations. Perhaps, the 3rd week of radiotherapy could be considered as the time-check-point.
Radiotherapy Oncology Department, IRCCS-CROB, Rionero in Vulture, Potenza, Italy. albafiorentino@hotmail.it
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Fiorentino
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Cozzolino
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Caivano
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Pedicini
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Chiumento
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Clemente
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Fusco
D054893:Cone-Beam Computed Tomography; D006258:Head and Neck Neoplasms / Q000000981:diagnostic imaging / Q000532:radiotherapy*; D006801:Humans; D010306:Parotid Gland / Q000528:radiation effects*; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted; D050397:Radiotherapy, Intensity-Modulated