Multi-slice computed tomography: A tool for non-invasive temperature measurement?

Figures & data

Figure 1. Experimental set-up featuring fluid-filled phantom with heating bath (white arrow) and thermometer with optical temperature probe (black arrow).

Table I.  Scan parameters used for the two sets of experiments.

parameter	Tube current-time product (mAs)	Tube voltage (kV)	Collimation (mm)	Slice thickness (mm)	Number of slices
Set 1	20–320	120	12 × 0.6	2.4	3
	(Interval: 20 mAs)		24 × 1.2	2.4, 4.8, 9.6	12, 6, 3
Set 2	250	80–140 (Interval: 20 kV)	12 × 0.6	2.4	3
			24 × 1.2	2.4, 4.8, 9.6	12, 6, 3

Table II.  Least square means of the standard deviation of area averaged CT numbers depending on tube current time product at 120 kV.

Tube current time product (mAs)	Standard deviation least square means
20	30.88
40	22.17
60	18.53
80	16.44
100	14.87
120	13.69
140	12.90
160	12.21
180	11.62
200	11.11
220	10.65
240	10.39
250	10.02
260	10.03
280	9.73
300	9.46
320	9.23

Table III.  Least square means of the standard deviation of area averaged CT numbers depending on tube voltage at 250 mAs.

Tube voltage (kV)	Standard deviation least square means
80	15.35
100	9.99
120	7.94
140	6.79

Table IV.  Least square means of the standard deviation of area averaged CT numbers depending on collimation and reconstructed slice thickness.

Collimation (mm)	Slice thickness (mm)	Standard deviation least square means
0.6	2.4	12.59
1.2	2.4	12.24
1.2	4.8	8.86
1.2	9.6	6.37

Table V.  Results of the regression analysis (temperature versus CT number) for the different fluids.

Fluid	Scanprotocol: tube voltage; tube current-time-product; collimation; slice thickness	Temperature
		n	Intercept	Regression Coeff.	SE	p-value	Root MSE	R-Square
0.9% NaCl	140 kV; 250 mAs; 1.2 mm; 9.6 mm	110	18.585	−0.471	0.0038	<0.0001	0.6335	0.9929
Water	140 kV; 250 mAs; 1.2 mm; 9.6 mm	110	8.041	−0.447	0.0036	<0.0001	0.5948	0.9931
Oil	140 kV; 250 mAs; 1.2 mm; 9.6 mm	110	−98.878	−0.679	0.0019	<0.0001	0.3204	0.9991
CM 1:32	140 kV; 250 mAs; 1.2 mm; 9.6 mm	110	191.064	−0.420	0.0027	<0.0001	0.4462	0.9956
CM 1:64	140 kV; 250 mAs; 1.2 mm; 9.6 mm	110	111.621	−0.414	0.0025	<0.0001	0.4162	0.9961
CM 1:128	140 kV; 250 mAs; 1.2 mm; 9.6 mm	110	64.282	−0.441	0.0021	<0.0001	0.3475	0.9976

Figure 2. Regression line for the relationship between temperature of water samples and measured CT number (imaging parameters: 250 mAs, 140 kV, 1.2 mm collimation, 9.6 mm slice thickness).

Figure 3. Regression line for the relationship between temperature of sunflower oil samples and measured CT number (imaging parameters: 250 mAs, 140 kV, 1.2 mm collimation, 9.6 mm slice thickness).