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Updated: Feb 7, 2026

Dosimetry for Cell Irradiation using Orthovoltage 40-300 kV X-Ray Facilities
Published on: February 20, 2021
Biological effectiveness of superficial X-ray in mammalian cells through precise dosimetry and Monte Carlo
Reham Barghash1, Piyawan Chailapakul2, Amber R Prebble3
1Colorado State University, Department of Environmental & Radiological Health Sciences, 1618 Campus Delivery, Fort Collins, CO, 80523, USA; College of Applied Medical Sciences, King Saud Bin Abdulaziz University for Health Sciences, Saudi Arabia; King Abdullah International Medical Research Center, King Saud Bin Abdulaziz University for Health Sciences, Riyadh, Saudi Arabia.
Abstract:
This study evaluates the radiobiological effectiveness comparing superficial X-rays to Cs-137 in V79 and U2OS cells cultured in T25 flasks using colony formation assays. Additional dosimetric care was given to maintaining equal absolute dose for all beam qualities, correcting for absorption and scattering in the flask, and quantifiable interpretation due to dose of the spatial differences in cell survival with significantly higher survival near the flask's edges. Ion chamber measurements quantified flask lid attenuation (6.9 %, 2.4 %, and 1.9 % for 50, 70, and 100 kVp), enabling dose correction for accurate survival analysis. CT-based Monte Carlo simulations revealed thicker flask walls and the meniscus effect created a 35 % dose reduction from flask center to edges, directly explaining the observed survival patterns. Monte Carlo simulation also predicted an increased secondary electron production at higher energies. These results emphasize the necessity of precise dosimetry in low-energy X-ray studies. Combined experimental and computational approaches enhanced reliability of radiobiological assessments. Survival curves yielded Relative Biological Effectiveness (RBE) values for 50 kVp X-ray of 1.45 (V79) and 1.64 (U2OS); 1.41 (V79) and 1.55 (U2OS) at 70 kVp; and 1.23 (V79) and 1.36 (U2OS) at 100 kVp, relative to Cs-137.
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