. 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 5.

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

Organ	α_O^a	β_O^b	R²^c	RMSE^d
Esophagus	−0.034	0.57	0.89	0.075
Heart	−0.024	0.56	0.86	0.076
Lungs	−0.026	0.49	0.91	0.058
Effective dose	−0.060	−2.4	0.84	0.0041

^{a, b}

α_O and β_O are fit coefficients for the equation relating CTDI_vol-normalized organ dose to chest diameter, nD_O(d_Chest) = exp(α_Od_Chest + β_O) and DLP-normalized effective dose, nED(d_Chest) = exp(α_Ed_Chest + 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 is estimated from the exponential relationship with fit parameters α_O and β_O, DLP dose-length product