Target coverage in head and neck cancer treated with intensity-modulated radiotherapy: a comparison between conventional and conformal techniques.
OBJECTIVE
We designed a comparative planning study aimed at quantifying the advantages of intensity-modulated radiotherapy (IMRT) over the conventional 3-field technique (3FT) and a 5-field conformal technique (5FCT) for head and neck (HN) cancer.


METHODS
We selected 9 patients treated at our institution with curative radiotherapy for a HN cancer. For all cases 4 plans were generated: 2 plans using the "standard" techniques (3FT and 5FCT), a third plan using IMRT, and a fourth "mixed" plan using IMRT followed by a conventional boost.


RESULTS
Our study confirmed literature data on the ability of IMRT to significantly decrease the dose received by organs at risk, compared with previous techniques. Target coverage was systematically better with 5FCT and IMRT than with 3FT. However, the increase in coverage of both PTV2 and PTV1 was only about 3-5% and this was achieved at the price of a similar increase in maximum dose (D1%). Volumetric parameters (V100%, V95%) were much more sensitive in detecting the improvement with IMRT.


CONCLUSIONS
The improvement of target coverage attained by IMRT, as compared with conventional and conformal techniques, might be overestimated by data currently available in the medical literature. If treatment with conventional techniques is planned using all tools provided by currently available fully 3-D planning systems, excellent target coverage can be obtained.
Palazzi
Mauro
M
Unit of Radiotherapy, Istituto Nazionale Tumori, Milan, Italy. mauro.palazzi@istitutotumori.mi.it
Orlandi
Ester
E
Pignoli
Emanuele
E
Lualdi
Manuela
M
Zonca
Giancarlo
G
Sangalli
Claudia
C
Stucchi
Claudio
C
Olmi
Patrizia
P
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006258:Head and Neck Neoplasms / Q000532:radiotherapy*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D021621:Imaging, Three-Dimensional; D008297:Male; D008875:Middle Aged; D011878:Radiotherapy / Q000379:methods; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted; D020266:Radiotherapy, Conformal; D050397:Radiotherapy, Intensity-Modulated