Table 1.

Comparison of conformation indices between conventional zero margin (ZM) plans and negative margin technique (NMT) plans for all tested cases in the systematic group

Case	$\mathit{\text{PTV}}\hspace{0.17em}({\mathit{\text{cm}}}^3)$	%Px Isodose (ZM/NMT)	AM SI (mm)	ARC Angle (°)	AM APRL (mm)	${\mathit{\text{CI}}}_{100}\hspace{0.17em}(\mathit{\text{ZM}})$	${\mathit{\text{CI}}}_{100}\hspace{0.17em}(\mathit{\text{NMT}})$	$\Delta {\mathit{\text{CI}}}_{100}\hspace{0.17em}(\%)$	${\mathit{\text{CI}}}_{50}\hspace{0.17em}(\mathit{\text{ZM}})$	${\mathit{\text{CI}}}_{50}\hspace{0.17em}(\mathit{\text{NMT}})$	$\Delta {\mathit{\text{CI}}}_{50}\hspace{0.17em}(\%)$	${M‐\mathrm{\text{CI}}}_{100}\hspace{0.17em}(\mathit{\text{ZM}})$	${M‐\mathrm{\text{CI}}}_{100}\hspace{0.17em}(\mathit{\text{NMT}})$	$\Delta {I‐\mathrm{\text{CI}}}_{100}\hspace{0.17em}(\%)$
1	20.5	80/76	$\mathrm{S}\&\mathrm{I}+3$	181–180	‐1	1.27	1.16	‐8.7	4.67	4.21	‐9.9	0.72	0.78	8.2
2	52.3	76/75	$\mathrm{S}\&\mathrm{I}+2$	181–260	NC	1.18	1.13	‐4.2	4.54	4.40	‐3.1	0.78	0.80	3.3
				261–330	A‐2, P‐3
				331–80	NC
				81–150	A‐2, P‐3
				151–180	NC
3	45.4	80/77	$\mathrm{S}\&\mathrm{I}+2$	181–220	NC	1.34	1.19	‐11.2	5.11	4.73	‐7.4	0.68	0.77	13.5
				221–316	A‐2, P‐5
				317–46	NC
				47–136	A‐2, P‐5
				137–180	NC
4	30.8	72.5/77	$\mathrm{S}+3,\hspace{0.17em}\mathrm{I}+4$	181–180	$\mathrm{A}\&\mathrm{R}+3,\hspace{0.17em}\mathrm{P}\&\mathrm{L}‐3$	1.38	1.17	‐15.2	5.35	5.21	‐2.6	0.66	0.77	17.8
5	32.3	80/80	$\mathrm{S}\&\mathrm{I}+3$	181–90	A‐l, R‐l	1.30	1.20	‐7.7	4.81	4.49	‐6.7	0.71	0.76	7.5
							Mean	‐9.4		Mean	‐5.9		Mean	10.1
							SD	4.1		SD	3.1		SD	5.7

%Px: = percent prescription; AM = aperture margin; S, I, A, P, R, and L = superior, inferior, anterior, posterior, right, and left directions (e.g., A‐2 indicates ‐2 mm margin in anterior direction); NC = no margin change; ACI = change of Cl from ZM to NMT in $\%\hspace{0.17em}=\hspace{0.17em}[\text{CI}(\text{NMT})\hspace{0.17em}/\hspace{0.17em}\text{CI}(\text{ZM})\hspace{0.17em}‐\hspace{0.17em}1]\hspace{0.17em}\times \hspace{0.17em}100$.