Analysis of diaphragm movements to specify geometric uncertainties of respiratory gating near end-exhalation for irradiation fields involving the liver dome

Hsiang-Kuang Tony Liang; Hideyuki Takei; Tetsuya Tomita; Toshiyuki Terunuma; Tomonori Isobe; Toshiyuki Okumura; Takeji Sakae; Hideyuki Sakurai

doi:10.1016/j.radonc.2022.04.018

Analysis of diaphragm movements to specify geometric uncertainties of respiratory gating near end-exhalation for irradiation fields involving the liver dome

Radiother Oncol. 2022 Jun:171:146-154. doi: 10.1016/j.radonc.2022.04.018. Epub 2022 Apr 21.

Authors

Hsiang-Kuang Tony Liang¹, Hideyuki Takei², Tetsuya Tomita³, Toshiyuki Terunuma⁴, Tomonori Isobe⁵, Toshiyuki Okumura⁶, Takeji Sakae², Hideyuki Sakurai⁷

Affiliations

¹ Department of Biomedical Engineering, National Taiwan University, Taipei, Taiwan; Department of Radiation Oncology, National Taiwan University Cancer Center Branch, National Taiwan University Hospital, Taipei, Taiwan; Division of Radiation Oncology, Department of Oncology, National Taiwan University Hospital, Taipei, Taiwan. Electronic address: hkliang@ntu.edu.tw.
² Faculty of Medicine, University of Tsukuba, Ibaraki, Japan; Proton Medical Research Center, University of Tsukuba Hospital, Ibaraki, Japan.
³ Department of Radiology, University of Tsukuba Hospital, Ibaraki, Japan.
⁴ Proton Medical Research Center, University of Tsukuba Hospital, Ibaraki, Japan.
⁵ Faculty of Medicine, University of Tsukuba, Ibaraki, Japan.
⁶ Departments of Radiation Oncology, University of Tsukuba Hospital, Tsukuba, Japan.
⁷ Departments of Radiation Oncology, University of Tsukuba Hospital, Tsukuba, Japan. Electronic address: hsakurai@pmrc.tsukuba.ac.jp.

PMID: 35461953
DOI: 10.1016/j.radonc.2022.04.018

Abstract

Background and purpose: The technique of gating near end-exhalation is commonly adopted to reduce respiration-associated geometric uncertainties for particle beam therapy. However, for irradiation fields involving the liver dome, how diaphragm movements generating liver-lung interface change, alongside geometric uncertainties, remain unspecified.

Methods and materials: Patients receiving respiratory-gated computed tomography (RGCT) with four-dimensional computed tomography (4DCT) scans during simulation were retrospectively reviewed. Differences (Δ) between RGCT and 4DCT images, including diaphragm displacements and liver-lung interface changes, were investigated to specify geometric uncertainties during early inhalation phases. Craniocaudal displacements (Δy, in sagittal/coronal planes) of diaphragm segments (dorsal/ventral/right lateral/medial), liver area changes (ΔA, in axial planes), and liver extent changes in specific directions of incidence (Δr, in axial planes) were analyzed.

Results: Altogether, 162 patients received simulating RGCT and 4DCT scans. In 22 of them, both images involved the liver dome. For most cases during early inhalation phases, the Δy values in the dorsal diaphragm were significantly greater than those in the ventral diaphragm (p < 0.05), the ΔA values were significantly enlarged with inhalation progressing (p < 0.05), and the Δr values in the dorsal direction were significantly larger than those in the ventral direction (p < 0.05). These results suggested that the dorsal diaphragm moves earlier and more in a caudal direction than the ventral diaphragm during early inhalation phases.

Conclusions: For respiratory-gated radiotherapy near end-exhalation and irradiation fields involving the liver dome, components of geometric uncertainties are temporospatial, including diaphragm segment movements, inhalation phases of irradiation, and beam angles of incidence.

Keywords: Diaphragm movement; Geometric uncertainties; Liver dome; Radiotherapy; Respiratory gating.

MeSH terms

Diaphragm / diagnostic imaging
Exhalation*
Four-Dimensional Computed Tomography / methods
Humans
Liver / diagnostic imaging
Lung Neoplasms* / radiotherapy
Movement
Respiration
Retrospective Studies