Fricke dosimetry analysis for cellular irradiation using 6 MV X-rays in 96-well plate format

Accurate dose verification is critical in small-volume in-vitro radiobiology, where planar dosimeters do not directly report the in-well (volumetric) dose.

To assess standard Fricke solution as an in-solution dosimeter for absorbed-dose verification in 96-well plates irradiated with 6 MV photon beams.

A standard Fricke solution was dispensed into 96-well plates and irradiated at 2, 4, 6, 8, and 10 Gy with a square field encompassing the plate footprint. Absorbance at 304 nm was used to compute dose via the Fricke formalism and converted to dose-to-water; results were compared against a calibrated 0.6-cc ionization chamber. Planar uniformity was checked with Gafchromic EBT-3 using triple-channel calibration with a simultaneous 0 Gy reference, and 8 × 12 well-wise dose heatmaps were generated.

Fricke readouts showed excellent linearity (R² = 0.9991) and high repeatability (plate-wide CV ≤ ∼2.5 %) across 2-10 Gy, with an average difference <1 % versus the ionization chamber. Film-based verification revealed no systematic off-axis gradients; well-wise median absolute differences (Fricke vs film) were ∼5-8 % across doses.

Fricke dosimetry provides a reliable, practical, and cost-effective in-well verification method for 96-well plate irradiations with megavoltage photons and complements planar film by directly probing the dose within the solution volume.