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Case Reports
. 2025 Oct;26(10):e70270.
doi: 10.1002/acm2.70270.

Breath-holding treatments in tomotherapy with active breathing coordinator: A first case report

April Meikwan Chow  1 , Ashley Chi Kin Cheng  2   3   4 , Louis Kit Yee Lee  1   3
Affiliations
Case Reports

Breath-holding treatments in tomotherapy with active breathing coordinator: A first case report

April Meikwan Chow et al. J Appl Clin Med Phys. 2025 Oct.

Abstract

Purpose: Respiratory motion poses a significant challenge in radiation therapy for thoracic and abdominal malignancies. For tomotherapy machines, it is even more challenging due to the 10-s warm-up time before initiating the treatment beams. A recent tomotherapy system upgrade has reduced this warm-up time to 0.5 s for the TomoDirect delivery mode, enabling the feasibility of performing breath-holding treatments. In this study, we investigated the feasibility of performing breath-holding treatments on a tomotherapy machine with spirometry technique.

Methods: A patient with gastric mucosa-assisted lymphoid tissue lymphoma was treated with deep inspiration breath holding (30 Gy in 20 fractions) on a tomotherapy machine with Active Breathing Coordinator™. An in-house visual system, featuring a compact 7″ LCD monitor, was implemented to provide visual feedback, allowing the patient to self-monitor their breathings and adhere to the prescribed pattern.

Results: The patient tolerated the breath-hold well for the entire treatment. The number of breath-holds for treatment was 9. The beam-on time for each field ranged from 12.4 to 19.7 s, average 15.2 s.

Conclusions: We have shown that BH treatment is feasible using an upgraded tomotherapy machine (Radixact v3.5) with Active Breathing Coordinator. Our proposed workflow includes an in-house visual system that allows patients to visualize their breathing patterns on-screen. This technique provides a practical solution for patients with thoracic and abdominal malignancies, addressing respiratory motion while minimizing radiation exposure for certain diseases.

Keywords: active breathing coordinator; breath‐holding treatment; tomotherapy.

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Conflict of interest statement

The authors have nothing to report.

Figures

FIGURE 1
FIGURE 1
Photo showing the ABC setup with the in‐house visual system.
FIGURE 2
FIGURE 2
Axial, sagittal and coronal planes for the dose distribution of the treatment plan.
FIGURE 3
FIGURE 3
Axial, sagittal and coronal planes of a set of typical matching images for positional verification. grey color: planning CT images; cyan colour: kVCT images taken during image guidance.
See this image and copyright information in PMC

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