Table 4.

Dosimetric gain by cutoff derived from left dataset applied to the right breast.

Characteristic	Supine better N = 27	Prone better N = 119	Odds ratio prone better	P value
Pre-dosimetry
Ratio breast depth prone/supine				0.552
≤ 1.6	9 (22.0%)	32 (78.0%)	0.76
> 1.6	18 (17.6%)	84 (82.4%)	1.31
Breast depth difference prone − supine				0.220
≤ 31 mm	8 (26.7%)	22 (73.3%)	0.56
> 31 mm	19 (16.8%)	94 (83.2%)	1.80
Breast depth prone				0.180
≤ 77 mm	8 (27.6%)	21 (72.4%)	0.53
> 77 mm	19 (16.7%)	95 (83.3%)	1.90
Breast volume/Body weight Ratio				0.012
≤ 4.9 mL/kg	8 (36.4%)	14 (63.6%)	0.29
> 4.9 mL/kg	16 (14.0%)	98 (86.0%)	3.50
Lower inner quadrant (LIQ)				0.930
LIQ	1 (20.0%)	4 (80.0%)	0.90
Not LIQ	26 (18.4%)	115 (81.6%)	1.11
Right breast volume supine				0.004
≤ 282 mL	8 (42.1%)	11 (57.9%)	0.24
> 282 mL	19 (15.0%)	108 (85.0%)	4.13
Left breast volume supine				0.164
≤ 347 mL	5 (31.2%)	11 (68.8%)	0.45
> 347 mL	22 (16.9%)	108 (83.1%)	2.23
Breast depth supine				0.035
≤ 38 mm	5 (41.7%)	7 (58.3%)	0.28
> 38 mm	22 (16.8%)	109 (83.2%)	3.54
Post-dosimetry
Penalty score prone				< 0.001
≥ 2.4 PoDP	12 (54.5%)	10 (45.5%)	0.11
< 2.4 PoDP	15 (12.1%)	109 (87.9%)	8.72
Penalty score supine				< 0.001
≤ 2.1 PoDP	17 (38.6%)	27 (61.4%)	0.17
> 2.1 PoDP	10 (9.8%)	92 (90.2%)	5.79

PoDP percent of dose prescription. Breast not specified is the right (ipsilateral) breast.