What the study found
The study found that a DBSCAN (density-based spatial clustering of applications with noise) clustering approach can be used to estimate DNA damage yields and assess ion beam quality. For protons, the normalized beam-quality measure showed a strong linear relationship with double-strand break yields, and a similar relationship was seen for carbon ions up to 200 keV µm⁻¹, after which an overkill effect appeared.
Why the authors say this matters
The authors conclude that the normalized Quality of Beam (QoB) measure, defined as clusters per keV of deposited energy, offers a biologically meaningful alternative to conventional metrics such as linear energy transfer (LET, a measure of how much energy radiation deposits per distance). They also state that the DBSCAN framework is computationally efficient compared with full water radiolysis modeling.
What the researchers tested
The researchers used simulated physical track structures to model DNA damage from 0.5-200 MeV protons. They assumed that energy deposition of at least 17.5 eV caused DNA damage, that at least two damage points within a distance ε formed a cluster, that isolated points were noise, and that the cluster-to-noise ratio matched the double-strand break-to-single-strand break yield ratio. They then applied the same framework and parameters to carbon ions.
What worked and what didn't
For protons, normalized QoB showed a strong linear correlation with double-strand break yields, allowing direct estimation of double-strand break and single-strand break yields using a single conversion factor. For carbon ions, the same linear relationship held up to LET values of 200 keV µm⁻¹, but beyond that the overkill effect emerged. The normalized QoB also qualitatively reproduced RBE-LET trends.
What to keep in mind
The abstract describes a simplified framework based on simulation and specific modeling assumptions, so the results are tied to those conditions. It also notes that the carbon-ion relationship changes beyond 200 keV µm⁻¹ because of overkill, so the reported linear behavior is not universal across all LET values.
Key points
- A DBSCAN clustering framework was used to estimate DNA damage yields from simulated radiation tracks.
- For protons, normalized QoB had a strong linear correlation with double-strand break yields.
- The same framework showed a similar linear relationship for carbon ions up to 200 keV µm⁻¹.
- Beyond 200 keV µm⁻¹ for carbon ions, the overkill effect appeared.
- The authors say the method is computationally efficient compared with full water radiolysis modeling.
Disclosure
- Research title:
- DBSCAN estimates DNA damage yields from proton and carbon ion beams
- Authors:
- Sanhanat Chaibura, Thiansin Liamsuwan
- Institutions:
- Chulabhorn Graduate Institute, Chulabhorn Graduate Institute, Chulabhorn Hospital, Chulabhorn Hospital, Chulabhorn Research Institute
- Publication date:
- 2026-02-24
- OpenAlex record:
- View
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