Table 6.

Dose comparison data for four spine SRS patients. The numerical value represents the average percent difference (for all four patients) in the dose metric relative to the value with no couch model included in the plan. Normal tissue constraints were chosen to fall in line with recommended tissue constraints from RTOG 0631

	No Couch Model	k Vu e RI	k Vu e RO	IGRT Couch
PTVD99	‐	$-2.02\%$	$-0.71\%$	$-0.51\%$
PTVD95	‐	$-2.04\%$	$-0.68\%$	$-0.49\%$
Spinal Cord Max	‐	$-1.48\%$	$-0.39\%$	$-0.19\%$
Spinal Cord (0.35 cc)	‐	$-2.03\%$	$-0.45\%$	$-0.38\%$
Skin D(10 cc)	‐	5.77%	5.71%	5.36%
Skin D(0.03 cc)	‐	3.60%	3.31%	2.63%