[4D-CT scan and radiotherapy for hepatocellular carcinoma: role in the definition of internal target volume (ITV)].
OBJECTIVE
To evaluate the role of 4D-CT scan and the breath-related margins in the definition of internal target volume (ITV) during radiotherapy for hepatocellular carcinoma.


METHODS
All patients treated for hepatocellular carcinoma that underwent a 4D-CT simulation scan were retrospectively analysed in order to assess breath-related movements of GTV in the 3-D directions. After a standard CT-scan simulation performed to contour GTV and organs at risk (OARs), a 4D-scan simulation was then realized in order to contour ITV. Margins to be added for every patient to pass from GTV to ITV were calculated and evaluated also regarding liver lobe and GTV size (< or>5 cm).


RESULTS
Twenty-seven hepatocellular carcinoma patients were evaluated (total: 28 lesions). Median tumor movements in the craniocaudal, lateral and anteroposterior direction were 8.6mm (range: 0-72.9 mm), 6.5mm (range: 1-68.1mm) and 9.1mm (range: 1-34 mm), respectively. ITV had a median volume increase of 94% (range: 8-403%).


CONCLUSIONS
Tumour breath-related displacements are significant. 4D-CT simulation scan allows to precisely define these displacements and to tailor the treatment. A precise evaluation of breath-related effects on GTV is essential, particularly with new conformal radiotherapy techniques as intensity modulated radiotherapy (IMRT) and/or stereotactic body radiotherapy.
EA3738, université Claude-Bernard Lyon 1 chemin du Grand-Revoyet, Pierre-Bénite, France. berardino.de-bari@chu-lyon.fr
B
B
De Bari
N
N
Sellal
F
F
Mornex
D006528:Carcinoma, Hepatocellular / Q000000981:diagnostic imaging / Q000532:radiotherapy*; D056973:Four-Dimensional Computed Tomography; D006801:Humans; D008113:Liver Neoplasms / Q000000981:diagnostic imaging / Q000532:radiotherapy*; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D055425:Respiratory-Gated Imaging Techniques; D012189:Retrospective Studies