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Radiotherapy of abdominopelvic primary or secondary lesions in conformational or stereotactic techniques is in full development. The small bowel is highly sensitive to irradiation and is the main organ at risk limiting prescription doses. This literature review aims to define the dose constraints to the small bowel and the duodenum in conformational and stereotactic body radiotherapy. The small bowel including the duodenum, jejunum and ileum is delineated on the simulation scanner. The radio-induced intestinal toxicities are acute related to the cellular depopulation of the intestinal mucosa, and late of more complex pathophysiology associating depletion in stem cells, microangiopathy, chronic inflammation and fibrosis. The main predictive factor of intestinal toxicity is the dose-volume ratio. In conformational radiotherapy, the dose constraints to the duodenum are: V25Gy<45% and V35Gy<20%. The jejunum and ileum dose constraints are for delineation by intestinal loop or peritoneal cavity respectively: V15Gy<275mL or V15Gy<830mL and V45Gy<150mL. In stereotactic body radiotherapy, small bowel dose constraints depend on fractionation and are defined on a small volume and on a maximum dose at one point. Intestinal toxicity is also dependent on factors intrinsic to the patient and radiosensitizers such as targeted therapies or chemotherapies. With the development of new techniques allowing dose escalation on the tumour and the development of inverse planning, the definition of dose constraints to the small bowel is essential for current practice., (Copyright © 2017 Société française de radiothérapie oncologique (SFRO). Published by Elsevier SAS. All rights reserved.)

Objective: To evaluate the dosimetric impact of breath-hold during radiotherapy of hepatocellular carcinoma (HCC) and to determinate the optimal respiratory phase for treatment (exhale or inhale)., Patients and Methods: Two CT scans were performed in inhale and in exhale in 20 patients with HCC. The GTV was delineated slice by slice on the inspiration breath hold acquisition (GTV(insp)) and on the expiration breath hold acquisition (GTV(exp)). The superposition of two GTV allowed to obtain the global GTV (free respiration). PTV was defined by adding a margin of 1cm around each GTV. The liver, the duodenum, the two kidneys, the stomach and the spinal cord were delineated on each acquisition as organs at risk (OAR). Three dosimetric plans were created on inspiration, expiration and on global PTV., Results: The mean reduction in the volume of PTV with conformal radiation therapy (3D-CRT) in the hold-breath group compared to the free respiration group was of 33.5+/-11.9%. The average difference of V50%, V20, V30, V40 and V50 were around 4% in favor of the breath hold. The average value of NTCP was 8.9% in free respiration, 4.5% in expiration and 3.2% in inspiration. Further improvement in the OARs dosimetric parameters for the breath hold was observed., Conclusion: Compared to the conformal radiotherapy with free respiration, the breath-hold allows reducing the volume of the PTV and the doses to the healthy liver and organs at risk. The use of this modality during different radiotherapy techniques (3D-CRT, IMRT and stereotactic) may be recommended. No difference in dosimetric value has been observed between the breath hold in expiratory and inspiratory phases.