[Benefit of a pretreatment planning library-based adaptive radiotherapy for cervix carcinoma?].
OBJECTIVE
In case of intensity-modulated radiotherapy (IMRT) for locally advanced cervix carcinoma, the objectives were to quantify the difference between the planned and the delivered doses by a standard irradiation, and to estimate the dosimetric benefit of a pretreatment planning library-based adaptive radiotherapy.


METHODS
Ten patients with locally advanced cervix carcinoma had three planning CTs corresponding to three bladder volumes: empty, intermediate (vi) and full. On each CT, two IMRT plans were generated to deliver 45 Gy to the planning target volume (PTV), with two different margins: clinical target volume (CTV)+10mm and CTV+15 mm. Using bi-weekly CBCTs, three scenarios of treatment have been simulated and compared: standard IMRT (one vi planning) with 10 and 15 mm margins and adaptive radiotherapy with 10mm margin. The cumulated dose in the organs at risk was estimated by elastic registration.


RESULTS
In case of standard IMRT, the cumulated dose was significantly different than the planning dose, with an under-dose of the CTV and the bladder, and an over-dose of the rectum and the peritoneal cavity. For 54% of the fractions, the adaptive radiotherapy planning was not based on vi. Considering the cumulated dose and compared to IMRT with 10-mm margin, adaptive radiotherapy increased the dose to the CTV (1.4 Gy for D98%) and decreased slightly the dose to the rectum and the peritoneal cavity. Compared to a standard IMRT with 15 mm margin, adaptive radiotherapy decreased significantly the dose to the rectum (20% for V40), the bladder (13% for V40) and the peritoneal cavity (2% for V35).


CONCLUSIONS
A pretreatment planning library-based adaptive radiotherapy in cervix carcinoma decreases the dose to the organs at risk and increases the dose to the CTV.
Département de radiothérapie, centre Eugène-Marquis, avenue Bataille-Flandre-Dunkerque, 35000 Rennes, France.
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M
Gobeli
Université de Rennes 1, LTSI, campus de Beaulieu, 35000 Rennes, France; Inserm U1099, campus de Beaulieu, 35000 Rennes, France.
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A
Simon
Département de radiothérapie, centre Eugène-Marquis, avenue Bataille-Flandre-Dunkerque, 35000 Rennes, France; Université de Rennes 1, LTSI, campus de Beaulieu, 35000 Rennes, France; Inserm U1099, campus de Beaulieu, 35000 Rennes, France.
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M
Getain
Département de radiothérapie, centre Eugène-Marquis, avenue Bataille-Flandre-Dunkerque, 35000 Rennes, France.
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J
Leseur
Université de Rennes 1, LTSI, campus de Beaulieu, 35000 Rennes, France; Inserm U1099, campus de Beaulieu, 35000 Rennes, France.
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E
Lahlou
Département de radiothérapie, centre Eugène-Marquis, avenue Bataille-Flandre-Dunkerque, 35000 Rennes, France; Université de Rennes 1, LTSI, campus de Beaulieu, 35000 Rennes, France; Inserm U1099, campus de Beaulieu, 35000 Rennes, France.
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C
Lafond
Université de Rennes 1, LTSI, campus de Beaulieu, 35000 Rennes, France; Inserm U1099, campus de Beaulieu, 35000 Rennes, France.
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E
Dardelet
Département de radiothérapie, centre Eugène-Marquis, avenue Bataille-Flandre-Dunkerque, 35000 Rennes, France.
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D
Williaume
Université de Rennes 1, LTSI, campus de Beaulieu, 35000 Rennes, France; Inserm U1099, campus de Beaulieu, 35000 Rennes, France.
B
B
Rigaud
Département de radiothérapie, centre Eugène-Marquis, avenue Bataille-Flandre-Dunkerque, 35000 Rennes, France; Université de Rennes 1, LTSI, campus de Beaulieu, 35000 Rennes, France; Inserm U1099, campus de Beaulieu, 35000 Rennes, France. Electronic address: r.de-crevoisier@rennes.unicancer.fr.
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R
de Crevoisier
D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D008875:Middle Aged; D011880:Radiotherapy Planning, Computer-Assisted; D050397:Radiotherapy, Intensity-Modulated; D002583:Uterine Cervical Neoplasms / Q000532:radiotherapy*
Adaptive radiotherapy; Cancer du col; Cervix carcinoma; IMRT; Image-guided radiotherapy; RCMI; Radiothérapie adaptative; Radiothérapie guidée par l’image