Table 2.

Summary of multivariate analysis

	Regression coefficient	Standard error	p value	Adjusted R2
Maximum dose
TZa	6.276	1.823	0.0010
CTRb	0.246	0.198	0.2185	0.221
BMIc	–0.556	0.223	0.0154
Mean dose
TZa	6.512	1.661	0.0002
CTRb	0.087	0.180	0.6309	0.219
BMIc	–0.391	0.203	0.0595
V20Gyd
TZa	13.313	4.069	0.0018
CTRb	0.456	0.441	0.3054	0.191
BMIc	–1.116	0.498	0.0287
V30Gyd
TZa	17.066	4.172	0.0001
CTRb	0.146	0.452	0.7484	0.243
BMIc	–1.115	0.511	0.0329
V40Gyd
TZa	17.190	4.101	< 0.0001
CTRb	–0.086	0.444	0.8478	0.275
BMIc	–0.973	0.502	0.0572

^a TZ = transition zone; ^b CTR = cardiothoracic ratio; ^c BMI = body mass index;

^d V20Gy, V30Gy, and V40Gy = percentage of left anterior descending artery volume receiving ≥ 20, ≥ 30, and ≥ 40 Gy, respectively.