. Author manuscript; available in PMC: 2016 Nov 1.

Published in final edited form as: Pediatr Radiol. 2015 Jul 4;45(12):1771–1780. doi: 10.1007/s00247-015-3400-2

Table 6.

Regression fit coefficients for CTDI_vol-normalized organ doses and DLP-normalized effective dose for abdominopelvic CT studies

Organ	α_O^a	β_O^b	R²^c	RMSE^d
Adrenals	−0.028	0.46	0.91	0.055
Bladder	−0.034	0.61	0.83	0.087
Gallbladder	−0.021	0.39	0.76	0.089
Kidneys	−0.025	0.52	0.91	0.062
Large intestines	−0.022	0.43	0.91	0.053
Liver	−0.023	0.37	0.89	0.064
Pancreas	−0.025	0.46	0.84	0.073
Small intestines	−0.022	0.47	0.93	0.052
Spleen	−0.018	0.23	0.53	0.080
Stomach	−0.021	0.37	0.82	0.071
Prostate	−0.034	0.21	0.35	0.162
Ovaries	−0.029	0.52	0.86	0.055
Uterus	−0.031	0.52	0.87	0.053
Bone surface	−0.020	1.33	0.32	0.381
Red marrow	−0.036	−0.02	0.66	0.065
Effective dose	−0.077	−2.5	0.92	0.0025

^{a, b}

α_O and β_O are fit coefficients for the equation relating CTDIvol-normalized organ dose to abdominopelvic diameter, nD_O(d_AP) = exp(α_Od_AP + β_O) and DLP-normalized effective dose, nED(d_AP) = exp(α_Ed_AP + β_E)

R² is the coefficient of determination for the fit

RMSE is the root mean squared error, defined as $\sqrt{\frac{1}{n} \sum_{i = 1}^{n} {(n D_{i} - {\hat{n D}}_{i})}^{2}}$ , where ${\hat{n D}}_{i}$ is the CTDI_vol-normalized organ dose estimated from the exponential relationship with fit parameters α_O and β_O, DLP dose-length product