Table 1.

The individual parameters for different fitting methods and different irradiation geometries.

Geometry	1	2	3
SSD (cm)	90	95	90
Field size (${\text{cm}}^2$)	$20\times 20$	$10\times 10$	$5\times 5$
Depth (cm)	10	5	10
Fitting parameters with one background and eight dose points
$P_0$	247	240	254
$P_s$	3585	3577	3209
m	30.80	33.58	40.18
Method I: Universal $P_s$ and $P_0$
Universal $P_0$	245	245	245
Universal $P_s$	3542	3542	3542
Ia (one point a ): m	31.28	33.37	37.62
Ib (two points b ): m	31.17	33.48	38.28
Method II: Universal $P_s$
$P_0$	247	240	254
Universal $P_s$	3542	3542	3542
IIa (one point a ): m	31.23	33.50	37.36
IIb (two points b ): m	31.11	33.63	37.98
Method III
$P_0$	247	240	254
IIIa (two points c ): $P_s$	3558	3494	3200
IIIb (three points d ): $P_s$	3538	3506	3200
IIIa (two points c ): m	30.91	33.95	40.19
IIIb (three points d ): m	31.10	33.80	40.16

^a Dose point: ~80 cGy

^b Dose points: ~40 and ~80 cGy

^c Dose points: ~40 and ~120 cGy

^d Dose points: ~40, ~80 and ~120 cGy