Ferrous sulfate Fe(SO₄)₂) PVA gels were investigated for a range of absorbed doses up to 20 Gy using both magnetic resonance imaging (MRI) and spectrophotometry to determine R₁ and optical density (OD) dose responses and G values. It was found that R₁- and OD-dose sensitivities increased with O₂ saturation or by the introduction of a freeze-thaw cycle during preparation of the PVA gel. The storage temperature of the Fe(SO₄)₂)PVA gel at - 18 °C increased R-dose sensitivity above that of gels stored at 5 °C. The addition of sucrose to the formulation was found to result in the largest increase in both R₁-and OD-dose sensitivities. Fe(SO₄)₂)PVA gel with and without the addition of xylenol orange was demonstrated to have a G value of Ο20 ions/100 eV and with sucrose Ο24 ions/100 eV.