. Author manuscript; available in PMC: 2010 May 11.

Published in final edited form as: Radiother Oncol. 2009 Aug 18;93(1):1–7. doi: 10.1016/j.radonc.2009.07.012

Table 2.

Tolerance limits for low contrast visibility (LCV), modulation transfer function (MTF), integral nonuniformity (IN) and contrast-to-noise ratio (CNR) for the LDPE insert calculated by the mean value plus or minus the 99% confidence interval (three times the standard deviation). For example, the mean value for LCV at the CBCT at the linac is 1.07% and the 99% confidence interval results in 0.31%, the tolerance for LCV for this device would be 1.38%. Depending on the parameter the lower or upper limit was used.

Device	LCV (%) – upper limit	MTF f₅₀ (lp/cm) – lower limit	MTF f₁₀ (lp/cm) – lower limit	IN – upper limit	CNR – lower limit
CT	1.24	2.45	4.28	0.005	29.8
CBCT linac	1.38	3.36	7.35	0.017	13.9
CBCT simulator	1.58	0.98	4.55	–	11.0