Table 1: Comparison of Prior RBE Calculations with the Present Study.

RBE was calculated using LD₅₀ values from 30-day survival studies in mice after whole-body irradiation. Irradiation was performed with high energy radionuclide γ-ray sources or megavoltage X-ray sources and compared to orthovoltage X-rays. HVL: Half-Value Layer.

Reference	High Energy Radiation	Orthovoltage X- rays	LD50/High (Gy)	LD50/Low (Gy)	R.B.E. (LD50/High/LD50/Low)
Kohn & Kallman, 1956	1000 kVp X-rays, 3.3 mm Pb HVL	250 kVp, 1.6 mm Cu HVL	7.58	6.36	1.19
Upton et al., 1956	Cobalt-60 γ-rays	250 kVp, 0.55 mm Cu HVL	7.30	5.28	1.38
Storer et al., 1957	Radium γ-rays	250 kVp, 2.6 mm Cu HVL	6.71	5.01	1.34
	Radium γ-rays	250 kVp, 2.6 mm Cu HVL	7.20	5.58	1.29
Paterson et al., 1957	4 MV X-Rays	300 kVp	7.47	5.61	1.33
Present Study	Cesium-137 γ-rays	300 kVp, 1 mm Cu HVL	8.12	6.72	1.21
	Cesium-137 γ-rays	300 kVp, 4 mm Cu HVL (Thoraeus)	8.12	7.42	1.09