Related Experiment Video
Updated: Feb 28, 2026
08:17
Dynamic Lung Tumor Tracking for Stereotactic Ablative Body Radiation Therapy
Published on: June 7, 2015
16.3K
Evaluation of the Dose Distribution Robustness for Lung Tumor Tracking in Robotic Radiotherapy Using Four-Dimensional
Yasuhide Miyabe1, Hiromu Yamanaka1, Hiroto Seki1
1Sapporo High Functioning Radiotherapy Center, Sapporo Kojinkai Memorial Hospital, Sapporo, JPN.
Cureus
|February 27, 2026
Summary
Four-dimensional CT (4DCT) simulations can reveal dose variations in CyberKnife Synchrony radiotherapy due to respiratory motion. This method helps assess treatment plan robustness by analyzing dose changes across different breathing phases, ensuring accurate lung tumor targeting.
Area of Science:
- Medical Physics
- Radiation Oncology
- Radiotherapy Technology
Background:
- Respiratory motion significantly impacts radiotherapy dose distribution and accuracy.
- The CyberKnife Synchrony system uses fiducial markers to track tumor motion during treatment.
- Current dose evaluation often relies on single-phase CT scans, neglecting respiratory phase variations.
Purpose of the Study:
- To assess the feasibility of using four-dimensional CT (4DCT) for evaluating dose variations in CyberKnife Synchrony treatments.
- To investigate the impact of respiratory phase differences on dose distribution during treatment planning.
- To determine if 4DCT simulations can identify potential dose coverage issues caused by breathing motion.
Main Methods:
- Two lung cancer patients treated with CyberKnife stereotactic radiotherapy (SRT) were analyzed.
- Reference treatment plans were created using end-expiratory breath-hold CT images.
- Dose calculations were performed on multiple respiratory-phase 4DCT images using the same beam parameters.
- Dose-volume histogram (DVH) metrics for target volumes and organs at risk (OARs) were compared to clinical goals.
Main Results:
- Patient 1 experienced significant dose reductions in the planning target volume (PTV) and clinical target volume (CTV) at an inspiratory phase, falling below the prescribed dose.
- Patient 2 showed minimal dose reductions in PTV and CTV, maintaining prescribed dose coverage.
- No clinically significant dose deterioration was observed for OARs in either patient.
Conclusions:
- 4DCT-based simulations are a viable method for evaluating dose variations related to respiratory phase during Synchrony treatments.
- This approach can identify potential underdosing issues caused by respiratory motion at the planning stage.
- 4DCT offers a supplementary tool to single-phase CT for assessing the robustness of radiotherapy plans against respiratory motion.
