Comparison of the neck image quality of two different CT scanners

Dionysios Drakopoulos, Mostafa El-Ashmawy, Lukas Ebner, Verena C Obmann, Alan A Peters, Dominik Sieron, Karol Szyluk, Adrian T Huber, Andreas Christe


Purpose: To compare image quality and radiation dose of two different CT scanners in neck imaging.

Material and Method: 200 consecutive patients with neck CT were selected from 2014 to 2017: 100 patients underwent a CT exam at CT1 and 100 patients were examined with CT2. At both CTs, a tube voltage of 120 kVp, and a reconstructed slice thickness of 3 mm with a soft Kernel were applied. The signal-to–noise ratio (SNR) and the contrast-to–noise ratio (CNR) were calculated from the level of the vertebral body C5. SNR and CNR were standardized to the dose level used (√(CTDI)). Mann Whitney test was applied to compare the image technical/quality parameters and the figure of merit (FOM) of both CTs.

Results: Significantly less radiation dose was administered at CT1 (9.5±6.7 mGy) compared to CT2 (11.6±2.1 mGy; P < 0.001). In contrast, the image parameters were superior on CT2: SNR and CNR were 8.1±3.0 and 11.0±6.1 at CT1 and 11.5±7.3 and 12.2±5.0 at CT2 (P < 0.001 and 0.024 respectively). The standardized SNR, CNR, and FOM were not significantly different between the two scanners.

Conclusion: The presented results suggest that CT2 provides significantly better image quality delineated by SNR and CNR when compared to CT1. However, the dose adjusted image quality and the figure of merit of the two CTs were the same.


Computed-Tomography; radiation dose; image quality; signal to noise; contrast to noise; figure of merit

Full Text:



Hall E, Brenner D. Cancer risks from diagnostic radiology. Br J Radiol. 2008; 81:362–378.

Christner JA, Kofler JM, McCollough CH. Estimating effective dose for CT using dose-length product compared with organ doses: consequences of adopting International Commission on Radiological Protection Publication 103 or dual-energy scanning. AJR Am J Roentgenol. 2010; 194:881–889.

Cody DD, Kim H-J, Cagnon CH, et al. Normalized CT dose index of the CT scanners used in the National Lung Screening Trial. AJR Am J Roentgenol. 2010; 194:1539–1546.

McCollough C, Branham T, Herlihy V, et al. Diagnostic reference levels from the ACR CT accreditation program. J Am Coll Radiol. 2011; 8:795–803.

Shrimpton P, Hillier M, Lewis M, Dunn M. National survey of doses from CT in the UK: 2003. Br J Radiol. 2006; 79:968–980.

McCollough C, Cody D, Edyvean S, et al. The measurement, reporting, and management of radiation dose in CT. Report of AAPM Task Group 23: CT Dosimetry Diagnostic Imaging Council CT Committee (2008).

Status of computed tomography dosimetry for wide cone beam scanners. International Atomic Energy Agency. IAEA human health reports 2011, ISSN 2074-7667; no. 5.

Mulkens T, Salgado R, Bellinck P. Dose Optimization and Reduction in CT of the Brain and Head and Neck Region. In: Tack D, Kalra MK, Gevenois PA, editors. Radiation Dose from Multidetector CT. Berlin, Heidelberg: Springer; 2011. pp. 281–306.

Smith-Bindman R, Lipson J, Marcus R, et al. Radiation dose associated with common computed tomography examinations and the associated lifetime attributable risk of cancer. Arch Intern Med. 2009; 169:2078–2086.

Newman B, Ganguly A, Kim JE, et al. Comparison of different methods of calculating CT radiation effective dose in children. Am J Roentgenol. 2012;199: W232–W239.

Kalender WA. Dose in x-ray computed tomography. Phy Med Biol. 2014; 59:R129–R150.

Brady Z, Ramanauskas F, Cain T, et al. Assessment of pediatric CT dose indicators for the purpose of optimization. British J Radiol. 2012; 85:1488–1498.

Langner S. Optimized imaging of the midface and orbits. GMS Curr Top Otorhinolaryngol Head Neck Surg. 2015:14.

Pantos I, Thalassinou S, Argentos S, et al. Adult patient radiation doses from non-cardiac CT examinations: a review of published results. Br J Radiol. 2011; 84:293–303.

International Commission on Radiations Units and Measurements, “ICRU Report 54 - Medical imaging – the assessment of image quality”(1996). [2] European Commission, “European guidelines on quality criteria for computed tomography”, Report EUR 16262 EN. Luxembourg: Office for Official Publications of the European Communities (1999).

Kalra MK, Maher MM, Toth TL, et al. Techniques and applications of automatic tube current modulation for CT. Radiology 2004; 233(3):649–657.

Kalra MK, Maher MM, D’Souza RV, et al. Detection of urinary tract stones at low- radiation-dose CT with z-axis automatic tube current modulation: phantom and clinical studies. Radiology 2005; 235(2):523–529.

Wilting JE, Zwartkruis A, van Leeuwen MS, et al. A rational approach to dose reduction in CT: individualized scan protocols. Eur Radiol 2001; 11(12):2627– 2632.

Turner A, Zankl M, Demarco JJ, et al. A method to estimate organ doses from multidetector row CT abdominal exams from patient-sized corrected CT dose index (CTDI) values: a Monte Carlo study. In: Radiological Society of North America scientific assembly and annual meeting program. Oak Brook, Ill: Radiological Society of North America, 2009; 472.

Schmidt B, Kalender WA. A fast voxel-based Monte Carlo method for scanner- and patient-specific dose calculations in computed tomography. PhysicaMedica 2002; 18(2):43–53.

Söderberg M, Gunnarsson M. Automatic exposure control in computed tomography: an evaluation of systems from different manufacturers. Acta Radiol 2010; 51(6):625-634.

Deak P, van Straten M, Shrimpton P.C, et al. Validation of a Monte Carlo tool for patient-specific dose simulations in multi-slice computed tomography. Eur Radiol 2008; 8(4):759–772.

Rizzo S, Kalra M, Schmidt B, et al. Comparison of angular and combined automatic tube current modulation techniques with constant tube current CT of the abdomen and pelvis. AJR Am J Roentgenol 2006;186 (3): 673–679.

McCollough CH, Bruesewitz MR, Kofler JM Jr. T dose reduction and dose management tools: an overview of available options. RadioGraphics 2006; 26(2):503– 512.

Graser A, Wintersperger BJ, Suess C, et al. Dose reduction and image quality in MDCT colonography using tube current modulation. AJR Am J Roentgenol 2006;187(3): 695–701.

Callahan MJ. CT dose reduction in practice. Pediatric Radiol 2011; 41:488–492.

Strauss KJ, Goske MJ, Kaste SC, et al. Image Gently: ten steps you can take to optimize image quality and lower CT dose for pediatric patients. AJR 2010; 194:868–873.



  • There are currently no refbacks.