Interfractional diaphragmatic position variation according to stomach volume change during respiratory‐gated radiotherapy for hepatocellular carcinoma

Abstract

Purpose We evaluated the correlation between stomach volume change and interfractional baseline shifts of the diaphragm in image‐guided radiotherapy (IGRT) for hepatocellular carcinoma (HCC). Materials and methods Twenty‐four patients with HCC underwent ten fractions of IGRT, and a total of 240 cone beam computed tomography (CBCT) and on‐board imager (OBI) kV image sets were acquired. These image sets were retrospectively analyzed. Baseline shifts of the diaphragm relative to bone and stomach volume change ratios were evaluated using four‐dimensional simulation CT, kV image, and CBCT images. Associations between baseline shifts and patient physiologic factors were investigated. Results The average baseline shift of the diaphragm in the superior‐inferior (SI) direction was 1.5 mm (standard deviation 4.6 mm), which was higher than the shift in other directions (0.7, 2.0 mm and 0.9, 2.6 mm in right‐left (RL) and anterior‐posterior (AP) directions, respectively). Interfractional baseline shifts of the diaphragm in the SI and AP directions were positively correlated with the stomach volume change ratio (Pearson's r: 0.416 and 0.302, p‐value: <0.001 and <0.001, respectively). Conclusions The interfractional baseline shifts of the diaphragm in the SI and AP directions correlated well with stomach volume changes. Efforts to maintain a constant stomach volume before the simulation and each treatment, such as fasting, may reduce interfractional baseline shifts of liver tumors.

Investigate the Dosimetric and Potential Clinical Benefits Utilizing Stereotactic Body Radiation Therapy With Simultaneous Integrated Boost Technique for Locally Advanced Pancreatic Cancer: A Comparison Between Photon and Proton Beam Therapy

“…The application of proton therapy in LAPC using SBRT still faces several challenges. Since organs such as the stomach and the small intestine have significant interfractionation uncertainties such as deformation and gas movement, the accuracy of beam delivery faces difficulties that are critical to the clinical implementation of SBRT (40). Thus, it limits the beam angle selection, which is mostly posterior or posterior oblique.…”

Accuracy of abdominal organ motion estimation in radiotherapy using the right hemidiaphragm top as a surrogate during prolonged breath‐holds quantified with MRI

“…These variations in DR may be caused by inter-fraction anatomical variation, such as stomach filling, which could influence displacements of nearby organs. 37,38 A strength of our study includes the typically longer durations of PBHs (2-12 min), 17 which enabled us to accurately analyze the validity of the RHT as surrogate for displacements of both hemidiaphragms and abdominal organs, since larger displacements occur during PBH compared to DIBH. It would be interesting to generalize our results to DIBH and/or FB, since these are used in clinical practice.…”

“…However, although the initial diaphragm position at the start of repeated PBHs was equal in three volunteers, the DRs during each of these PBHs varied. These variations in DR may be caused by inter‐fraction anatomical variation, such as stomach filling, which could influence displacements of nearby organs 37,38 …”