<abstract xmlns="http://www.w3.org/1999/xhtml"><sec id="j_1905-7415.1003.490_s_001_w2aab3b7b8b1b6b1aab1c16b1Aa"><h3>Background</h3><p>Radiation exposure because of medical imaging is a public safety concern.</p></sec><sec id="j_1905-7415.1003.490_s_002_w2aab3b7b8b1b6b1aab1c16b2Aa"><h3>Objective</h3><p>To optimize a protocol for multi-detector computed tomography (MDCT) of the chest with pulmonary nodules based on targeted standard deviation (SD) to achieve minimal patient radiation exposure, while maintaining acceptable diagnostic information.</p></sec><sec id="j_1905-7415.1003.490_s_003_w2aab3b7b8b1b6b1aab1c16b3Aa"><h3>Methods</h3><p>A Lungman chest phantom with 5 spheres simulating nodules of 12, 10, 8, 5, and 3 mm diameters at 100 Hounsfield Units (HU) was scanned by 320-slice MDCT by varying targeted SD of 9, 14, 20, and 25, beam pitch of 0.637, 0.813, 1.388, at 120 and 100 kVp, and 10-400 mA. We measured the radiation doses in terms of corresponding volume computed tomography dose index (CTDI<sub>vol</sub>). Quantitative image quality was determined by the percent contrast-to-noise ratio (%CNR). Two independent radiologists evaluated images for nodule detection acceptability on a 5-point rating scale.</p></sec><sec id="j_1905-7415.1003.490_s_004_w2aab3b7b8b1b6b1aab1c16b4Aa"><h3>Results</h3><p>We found targeted SD increased results in decreased radiation dose and %CNR. We found CTDI<sub>vol</sub> reduction between –40% and –88% compared with the default setting for various targeted SD, beam pitch, and kVp. The %CNR was highest at targeted SD 9. There was good agreement between the image quality scores by 2 independent readers (k = 0.66).</p></sec><sec id="j_1905-7415.1003.490_s_005_w2aab3b7b8b1b6b1aab1c16b5Aa"><h3>Conclusion</h3><p>Targeted SD 20, 10-400 mA at pitch 0.813 and 120 kVp on a nodule size of 5 mm was considered the optimal protocol for low-dose chest CT. Our recommended protocol can reduce the radiation dose substantially under the manufacturer’s default protocol, while preserving acceptable image quality for lung nodule detection.</p></sec></abstract>

BackgroundRadiation exposure because of medical imaging is a public safety concern.ObjectiveTo optimize a protocol for multi-detector computed tomography (MDCT) of the chest with pulmonary nodules based on targeted standard deviation (SD) to achieve minimal patient radiation exposure, while maintaining acceptable diagnostic information.MethodsA Lungman chest phantom with 5 spheres simulating nodules of 12, 10, 8, 5, and 3 mm diameters at 100 Hounsfield Units (HU) was scanned by 320-slice MDCT by varying targeted SD of 9, 14, 20, and 25, beam pitch of 0.637, 0.813, 1.388, at 120 and 100 kVp, and 10-400 mA. We measured the radiation doses in terms of corresponding volume computed tomography dose index (CTDIvol). Quantitative image quality was determined by the percent contrast-to-noise ratio (%CNR). Two independent radiologists evaluated images for nodule detection acceptability on a 5-point rating scale.ResultsWe found targeted SD increased results in decreased radiation dose and %CNR. We found CTDIvol reduction between –40% and –88% compared with the default setting for various targeted SD, beam pitch, and kVp. The %CNR was highest at targeted SD 9. There was good agreement between the image quality scores by 2 independent readers (k = 0.66).ConclusionTargeted SD 20, 10-400 mA at pitch 0.813 and 120 kVp on a nodule size of 5 mm was considered the optimal protocol for low-dose chest CT. Our recommended protocol can reduce the radiation dose substantially under the manufacturer’s default protocol, while preserving acceptable image quality for lung nodule detection.

Optimization of a low-dose 320-slice multi-detector computed tomography chest protocol using a phantom

Asian Biomedicine

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

BackgroundRadiation exposure because of medical imaging is a public safety concern.ObjectiveTo optimize a protocol for multi-detector computed tomography...

kVp	Pitch	%CTDI_vol reduction

		Targeted SD

		9	14	20	25
100	0.637	+1.69	–59.32	–77.97	–86.44
100	0.813	–10.16	–57.63	–79.66	–86.44
100	1.388	+5.08	61.02	77.97	84.75
120	0.637	+18.64	–47.54	–79.66	–84.74
120	0.813	0 (default)	–40.68	–81.35	–88.14
120	1.388	+10.17	–54.24	–77.97	–84.74

Optimization of a low-dose 320-slice multi-detector computed tomography chest protocol using a phantom

Article Category: Technical report (Original)

Published Online: Jan 31, 2017

Page range: 269 - 276

DOI: https://doi.org/10.5372/1905-7415.1003.490

Keywords
CT chest, CT noise index, MDCT, radiation dose reduction, targeted SD

© 2016 Chatnapa Nuntue, Anchali Krisanachinda, Kitiwat Khamwan

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Radiation exposure from various targeted SD and helical pitch at 120 and 100 kVp

The percent reduction of CTDIvol compared with the default setting protocol with increasing targeted SD and helical pitch at 100 and 120 kVp

kVp	Pitch	Targeted SD	CTDI_vol (mGy)
120	0.637	9	7
		14	3.1
		20	1.2
		25	0.9
	0.813	9	5.9
		14	2.5
		20	1.1
		25	0.7
	1.388	9	6.5
		14	2.7
		20	1.3
		25	0.9
100	0.637	9	6
		14	2.4
		20	1.3
		25	0.8
	0.813	9	5.3
		14	2.5
		20	1.2
		25	0.8
	1.388	9	6.2
		14	2.4
		20	1.4
		25	0.9

Optimization of a low-dose 320-slice multi-detector computed tomography chest protocol using a phantom

Article Category: Technical report (Original)

Published Online: Jan 31, 2017

Page range: 269 - 276

DOI: https://doi.org/10.5372/1905-7415.1003.490

KeywordsCT chest, CT noise index, MDCT, radiation dose reduction, targeted SD

© 2016 Chatnapa Nuntue, Anchali Krisanachinda, Kitiwat Khamwan

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Radiation exposure from various targeted SD and helical pitch at 120 and 100 kVp

The percent reduction of CTDIvol compared with the default setting protocol with increasing targeted SD and helical pitch at 100 and 120 kVp

Keywords
CT chest, CT noise index, MDCT, radiation dose reduction, targeted SD