Table 4.

Regression fit coefficients for CTDI_vol-normalized organ doses and DLP-normalized effective dose for chest–abdomen–pelvis CT studies

Organ	αOa	βOb	R2c	RMSEd
Adrenals	−0.027	0.49	0.92	0.050
Bladder	−0.034	0.62	0.83	0.088
Esophagus	−0.029	0.49	0.90	0.071
Gallbladder	−0.023	0.46	0.84	0.089
Heart	−0.021	0.53	0.89	0.066
Kidneys	−0.027	0.58	0.92	0.069
Large intestines	−0.022	0.45	0.93	0.050
Liver	−0.023	0.46	0.92	0.070
Lungs	−0.023	0.47	0.93	0.055
Pancreas	−0.024	0.51	0.89	0.061
Small intestines	−0.022	0.47	0.93	0.052
Spleen	−0.022	0.39	0.77	0.087
Stomach	−0.020	0.42	0.86	0.066
Prostate	−0.032	0.19	0.33	0.165
Ovaries	−0.032	0.57	0.88	0.053
Uterus	−0.031	0.52	0.89	0.049
Bone surface	−0.034	1.86	0.98	0.123
Red marrow	−0.033	0.44	0.97	0.037
Effective dose	−0.057	−2.8	0.95	0.0022

^{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)

^cR² is the coefficient of determination for the fit

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