Related Experiment Video
Updated: Jun 29, 2025
08:54
Treatment of Liver Metastases Using an Internal Target Volume Method for Stereotactic Body Radiotherapy
Published on: May 8, 2018
14.2K
Radiobiological evaluation considering the treatment time with stereotactic radiosurgery for brain metastases
Hisashi Nakano, Takeshi Takizawa, Daisuke Kawahara1
1Department of Radiation Oncology, Institute of Biomedical and Health Sciences, Hiroshima University, 1-2-3 Kasumi, Minami-ku, Hiroshima-shi, Hiroshima, Japan.
BJR Open
|March 25, 2024
Summary
Stereotactic radiosurgery (SRS) treatment time, including interruptions, impacts tumor radiobiological effects. Longer treatment times in brain SRS using the CyberKnife system reduced target dose distribution and conformity indices.
Area of Science:
- Radiation Oncology
- Medical Physics
- Cancer Biology
Background:
- Stereotactic radiosurgery (SRS) is a precise radiation technique for treating brain metastases.
- The duration of SRS, including treatment and interruption times, may influence radiobiological outcomes.
- Evaluating the impact of treatment time on dose distribution is crucial for optimizing SRS efficacy.
Purpose of the Study:
- To evaluate the radiobiological effect of irradiation and interruption times during SRS using the CyberKnife (CK) system for brain metastases.
- To assess how treatment time influences dose distribution and radiobiological dose in the gross tumor volume (GTV).
Main Methods:
- Utilized DICOM data and irradiation log files from 10 patients with non-small-cell lung cancer (NSCLC) brain metastases treated with SRS.
- Employed a microdosimetric kinetic model (MKM) to evaluate radiobiological effects, incorporating biological parameters from NCI-H460 cells.
- Calculated radiobiological dose (GTV_bio), D95, Radiation Therapy Oncology Group conformity index (RCI), and Paddick conformity index (PCI) under varying DNA repair rates.
Main Results:
- Mean D95, RCI, and PCI for GTV_bio were 98.8%, 0.90, and 0.80, respectively, and these values decreased with increased treatment time.
- At a DNA repair constant rate (a+c) of 2.0, the mean D95, RCI, and PCI for GTV_bio were 94.9%, 0.71, and 0.49, respectively.
- Results indicate a negative correlation between treatment time and dosimetric indices, highlighting the impact of interruptions.
Conclusions:
- The radiobiological effect of treatment time in brain SRS using the CyberKnife system was accurately evaluated.
- Radiobiological dose assessment considering treatment time can lead to more precise dose evaluation for metastatic brain tumors treated with CK SRS.
