## 3 Results
### Image Quality  
Figure 4 shows the spatial resolution limits for the four fluoroscopy units, whereas Figure 5 presents the results of the minimum contrast detail detectability measurements performed using Leeds TO.10. The graphs show an improved image quality for fluoroscopy with FPDs compared to image intensifier-based fluoroscopy. \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multirow{2}{*}{**Code**} & **Output@** & \multirow{2}{*}{**HVL**} & \multirow{2}{*}{**Accuracy (\%) a**} & \multirow{2}{*}{**Field Size b**} & **Contrast** \\  & **80 kVp** & & **(mm Aleq)** & & & **Fluoro** & **Radiography** & **X** & **Y** \\ \hline EC Criteria & 25-90 & 70 kVp & 80 kVp & 10 & 5 & \textless{1\% of SID} & 3\% \\ \hline \multicolumn{8}{c}{Unit 1} \\ Frontal & 68 & 3.0 & 3.5 & 5.4 & 2 & \textless{1} & \textless{1} & 1.3 \\ Lateral & 75 & 3.0 & 3.5 & 4.2 & 1.6 & \textless{1} & \textless{1} & 1.3 \\ \multicolumn{8}{c}{Unit II} \\ Frontal & 56 & 2.9 & 3.3 & 4.5 & 3.0 & \textless{1} & \textless{1} & 1.3 \\ Lateral & 59 & 2.8 & 3.2 & 3.6 & 2.2 & \textless{1} & \textless{1} & 1.3 \\ \hline \hline \end{tabular}  
* kVp accuracy (%) = \(100*\left(kV_{p}^{rat}-kV_{p}^{mean}\right)/kV_{p}^{rat}\), where \(kV_{p}^{rat}\) and \(kV_{p}^{mean}\) are the set and the measured kVp, respectively. b The Unfors ruler was imaged at the four boundaries of the light-indicated radiation field.  
\end{table} 
Table 1: Summary for testing of major X-ray tube and generator parameters. \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multicolumn{1}{c}{**Unit**} & **Dose Quantity** & **Measured** & **Indicated** & **Error \%** \\ \hline \multicolumn{8}{c}{UNIT I} \\ Frontal & KAP (mGy.cm\({}^{2}\)) & 1114 & 1092 & 2.0 \\ \multicolumn{8}{c}{CAK(mGy)} & 2.21 & 2.00 \\ Lateral & KAP (mGy.cm\({}^{2}\)) & 1037 & 962 & 7.7 \\ \multicolumn{8}{c}{CAK (mGy)} & 2.98 & 3.00 \\ \multicolumn{8}{c}{UNIT II} \\ Frontal & KAP (mGy.cm\({}^{2}\)) & 135 & 156 & 13.0 \\ \multicolumn{8}{c}{CAK (mGy)} & 1.02 & 1.2 & 16.0 \\ Lateral & KAP (mGy.cm\({}^{2}\)) & 171 & 180 & 6 \\ \multicolumn{8}{c}{CAK (mGy)} & 2.2 & 2.4 & 8.3 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: KAP and CAK accuracy measurements. \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multicolumn{1}{c}{**Pantom**} & \multicolumn{4}{c}{**Unit II Frontal**} & \multicolumn{4}{c}{**Unit II Lateral**} \\ \hline \multirow{2}{*}{**PMMA**} & **AL** & \multicolumn{2}{c}{**Kilovoltage**} & \multicolumn{2}{c}{**ESAK**} & \multicolumn{2}{c}{**Kilovoltage**} & \multicolumn{2}{c}{**ESAK**} \\
**cm** & **mm** & **Indicated** & **Measured** & **Error \%** & **(mGy/min)** & **Indicated** & **Measured** & **Error \%** & **(mGy/min)** \\ \hline
1.0 & & 53.00 & 56.83 & 7.23 & 0.62 & 55.00 & 55.35 & 0.64 & \\
3.0 & & 58.13 & 55.00 & \(-\)5.38 & 0.94 & 59.00 & 60.95 & 3.31 & \\
5.5 & & 62.17 & 59.00 & \(-\)5.10 & 2.01 & 61.00 & 61.91 & 1.49 & 0.88 \\
10.5 & & 66.13 & 64.00 & \(-\)3.22 & 3.96 & 63.00 & 64.94 & 3.08 & 2.81 \\
15.0 & & 70.00 & 68.00 & \(-\)2.86 & 6.45 & 68.00 & 69.80 & 2.65 & 5.77 \\
18.0 & & 74.30 & 73.00 & \(-\)1.75 & 10.15 & 72.00 & 75.80 & 5.28 & 11.69 \\
18.0 & 2.5 & 75.90 & 75.00 & \(-\)1.19 & 11.99 & 75.00 & 80.20 & 6.93 & 10.30 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: kVp accuracy with fluoroscopy operated in automatic exposure dose rate mode.