Optimizing and assessing the clinical effectiveness of deep-inspiration breath hold compared to free breathing in radiotherapy for gastric lymphoma.

416 Background: Variable anatomy, prompted by bowel filling and respiratory motion, necessitates larger margins for planning target volumes (PTV) in radiotherapy for gastric lymphoma patients, leading to higher doses to organs at risk (OAR). The deep inspiratory breath-holding (DIBH) technique during radiotherapy has emerged as a protective method that improves OAR sparing. Therefore, this systematic review aims to systematically evaluate the benefits of DIBH compared to free breathing (FB) techniques during radiotherapy for gastric lymphomas, along with the physiological mechanisms involved. Methods: This systematic review included three comparative studies following a comprehensive search across PubMed, Google Scholar, and the Cochrane Library, involving a total of 33 patients with gastric lymphomas, in whom radiotherapy was planned under both DIBH and FB. The radiotherapeutic techniques assessed were intensity-modulated radiotherapy (IMRT), 3D-conformal radiotherapy (3D-CRT), step-and-shoot IMRT (SIMRT), volumetric-modulated arc therapy (VMAT), and tomotherapy. The dosimetric parameters included Gy (Gray), mean dose (Dmean), maximum dose (Dmax), etc. Results: Median heart dose (MHD) showed a consistent and significant reduction with DIBH across all techniques, including IMRT: 4.9→2.6 Gy; 3D: 8.54→4.46 Gy; SIMRT: 6.97→3.63 Gy; VMAT: 6.83→3.42 Gy; and tomotherapy: 7.06→3.80 Gy (all p