Backscatter radiation at tissue-titanium interfaces. Biological effects from diagnostic 65 kVp x-rays

Area of Science:

• Radiobiology
• Biomaterials Science
• Medical Imaging

Background:

• Titanium implants are widely used in tissue reconstruction, often requiring radiographic assessment.
• Secondary electrons induced by diagnostic X-rays at tissue-metal interfaces may cause cellular damage.
• Understanding radiation effects on cells near titanium is crucial for patient safety during dental radiography.

Purpose of the Study:

• To compare the biological effects of diagnostic X-ray radiation on cultured mammalian cells grown on titanium versus plastic plates.
• To assess the radiobiological effectiveness and dose sensitivity of cells in proximity to titanium surfaces.

Main Methods:

• Cultured mammalian cells were grown on titanium and plastic plates.
• Cells were irradiated with diagnostic X-ray energies (65 kV) at high doses (0.7-5 Gy).
• Cell survival curves were analyzed to determine radiation sensitivity and biological effects.

Main Results:

• Cells grown on titanium plates exhibited significantly higher sensitivity to X-ray irradiation compared to those on plastic plates.
• The survival curve for cells on titanium showed a steeper slope and lacked a shoulder, resembling high Linear Energy Transfer (LET) radiation effects.
• While cellular survival decreased near titanium, the study suggests minimal biological impact from typical dental X-ray doses.

Conclusions:

• Titanium surfaces may alter the radiobiological response of adjacent cells to diagnostic X-rays, potentially due to increased local dose or modified effectiveness.
• Postoperative intraoral radiography following titanium implantation is unlikely to pose a significant risk of acute healing disturbances.
• The biological effects near titanium implants from standard dental X-ray doses are estimated to be below thresholds for acute effects.