Purpose: To evaluate the amplitude of motion and the variations of volume of the tumor, the liver and upper abdominal organs induced by breathing during the irradiation of hepatocellular carcinoma (HCC).
Material and methods: Two scanners were performed in inhale and in exhale not forced in 20 patients with a HCC. The liver (left/right lobes), the tumor, the duodenum, the two kidneys and the pancreas were delineated on each acquisition. The superposition of the two spirals made it possible to measure the displacements and variations of volume of these structures in the craniocaudal (CC), lateral (Lat), and anteroposterior (AP) directions.
Results: The mean displacement of the tumour in CC, Lat and AP was of 19.7+/-8.3 mm, 4.5+/-2.3 mm, and 8.9+/-6.5 mm. The greatest amplitude of movement was obtained in CC for the right and left hepatic lobes (19+/-6.5 mm, 10+/-5.6 mm), the duodenum(12.6+/-6.4 mm), the kidneys right and left (15.5+/-6.1 mm, 16.2+/-10 mm) and the pancreas (13.2+/-6 mm). No significant variation of volume was observed for these organs.
Conclusion: The movements of the tumour, the liver and the abdominal organs, induced by breathing are significant. The respiratory gating appears essential in particular with the development of new techniques of irradiation such as the intensity-modulated radiotherapy (IMRT) or the stereotactic body radiation therapy (SBRT).