The impact of integrated circuit detector technology in routine MDCT: Improved image quality compared to conventional detector design for constant SSDE

Khoschy Schawkat, Ralph M. Fischer, Johannes T. Heverhagen, Andreas Christe

Abstract


Purpose: The aim of this study was to compare the image quality and radiation dose of routine CT scans acquired with a third-generation scanner built with integrated circuit detector technology (Stellar®-detector) to those acquired with a conventional solid-state detector (UFC-ultra fast ceramic solid-state detector) equipped with a discrete system using the same protocol setting on the same 128-MDCT scanner.

Material and Methods: 262 routine CT examinations of 240 patients (140 male, 100 female) with a mean age of 61.7 years (range: 20-89 years) were reviewed retrospectively. 131 examinations were acquired with a UFC solid-state detector and 131 with the new digital Stellar®-detector (23 CT chest and abdomen, 50 CT chest and 58 CT abdomen). The following parameters were recorded: BMI, scan length, kVp, CT dose index (CTDIvol) and dose-length-product (DLP). CTDIvol multiplied with a conversion factor depending on the patient size determined the size-specific dose estimates (SSDE). The image noise was defined as standard deviation of mean attenuation values in Hounsfield units and was quantitatively assessed by circular region of interest at predefined size of 31.4 mm2 (20 mm diameter) manually placed in the center of the left liver lobe. Iterative reconstruction (SAFIRE, level 3) was used.

Results: Changing the detector unit from a UFC solid-state detector with distributed electronics (conventional) to a fully-digital Stellar® detector leads to a significant decrease of image noise by 7.5% in the liver (mean ± SD: 25.5 ± 5.4 HU vs. 23.6 ± 5.8 HU; p=0.0019) for all CT scans included in this study. In the subgroup CT chest (n=100) the average noise reduction was 6% (mean ± SD: 28.2 ± 5.7 HU vs. 26.5 ± 7.1 HU; p=0.038) and 6,4% for the subgroup CT abdomen (n=116) (mean ± SD: 23.2 ± 3.7 HU vs. 21.9 ± 3.7 HU; p=0.022). kVp, mAs and total scan length were the strongest predictors for effective dose (ED, p<0.0001) whereas SSDE shows a strong positive correlation with kV, mAs and effective diameter (p<0.0001). The liver noise correlates negatively with both ED as well as SSDE (p=0.0002 and p<0.0001, respectively).

Conclusion: For the same applied radiation level the implementation of an integrated circuit digital detector reduces image noise compared to detectors having distributed electronics. Using a detector with integrated circuit detector technology provides great potential to reduce radiation dose. Further measures such as changing the CT-image noise level must be performed to achieve dose reduction.


Keywords


tomography, x-ray computed/instrumentation; multidetector; radiation dosage; effective dose; size specific dose estimate

Full Text:

PDF

References


Amis ES Jr., Butler PF, Applegate KE, et al. American College of Radiology white paper on radiation dose in medicine. J Am Coll Radiol 2007; 4(5): 272-284.

Lee TY, Chhem RK. Impact of new technologies on dose reduction in CT. Eur J Radiol 2010; 76(1): 28-35.

Mettler FA Jr., Bhargavan M, Faulkner K, et al. Radiologic and nuclear medicine studies in the United States and worldwide: Frequency, radiation dose, and comparison with other radiation sources-1950-2007. Radiology 2009; 253(2): 520-531.

Amis ES Jr. CT radiation dose: Trending in the right direction. Radiology 2011; 261(1): 5-8.

Sodickson A, Baeyens PF, Andriole KP, et al. Recurrent CT, cumulative radiation exposure, and associated radiation-induced cancer risks from CT of adults. Radiology 2009; 251(1): 175-184.

Brenner DJ, Hall EJ. Computed tomography-an increasing source of radiation exposure. N Engl J Med 2007; 357(22): 2277-2284.

Pearce MS, Salotti JA, Little MP, et al. Radiation exposure from CT scans in childhood and subsequent risk of leukaemia and brain tumours: a retrospective cohort study. Lancet 2012; 380(9840): 499-505.

Preston DL, Ron E, Tokuoka S, et al. Solid cancer incidence in atomic bomb survivors: 1958-1998. Radiat Res 2007; 168(1): 1-64.

Boedeker KL, Cooper VN, McNitt-Gray MF. Application of the noise power spectrum in modern diagnostic MDCT: Part I. Measurement of noise power spectra and noise equivalent quanta. Phys Med Biol 2007; 52(14): 4027-4046.

Frush DP, Donnelly LF, Rosen NS. Computed tomography and radiation risks: What pediatric health care providers should know. Pediatrics 2003; 112(4): 951-957.

Morsbach F, Bickelhaupt S, Ratzer S, et al. Integrated circuit detector technology in abdominal CT: Added value in obese patients. AJR Am J Roentgenol 2014; 202(2): 368-374.

Duan X, Wang J, Leng S, et al. Electronic noise in CT detectors: Impact on image noise and artifacts. AJR Am J Roentgenol 2013; 201(4): W626-32.

Christner JA, Braun NN, Jacobsen MC, et al. Size-specific dose estimates for adult patients at CT of the torso. Radiology 2012; 265(3): 841-847.

Brady SL, Kaufman RA. Investigation of American Association of Physicists in Medicine Report 204 size-specific dose estimates for pediatric CT implementation. Radiology 2012; 265(3): 832-840.

Christe A, Heverhagen J, Ozdoba C, et al. CT dose and image quality in the last three scanner generations. World J Radiol 2013; 5(11): 421-429.

He J, Zu Y, Wang Q, et al. Improving depiction of temporal bone anatomy with low-radiation dose CT by an integrated circuit detector in pediatric patients: A preliminary study. Medicine (Baltimore) 2014; 93(28): e325.

Korn A, Bender B, Spira D, et al. Added value of integrated circuit detector in head CT: Objective and subjective image quality in comparison to conventional detector design. Acad Radiol 2014; 21(12): 1506-1511.

Brodoefel H, Bender B, Schabel C, et al. Potential of combining iterative reconstruction with noise efficient detector design: Aggressive dose reduction in head CT. Br J Radiol 2015; 88(1050): 20140404.

Geyer LL, Glenn GR, De Cecco CN, et al. CT Evaluation of Small-Diameter Coronary Artery Stents: Effect of an Integrated Circuit Detector with Iterative Reconstruction. Radiology 2015; 276(3): 706-714.

Kulkarni NM, Pinho DF, Kambadakone AR, et al. Emerging technologies in CT- radiation dose reduction and dual-energy CT. Semin Roentgenol 2013; 48(3): 192-202.

Recommendations of the International Commission on Radiological Protection. Ann ICRP 1991; 21(1-3): 1-201.

McCollough CH, Schueler BA. Calculation of effective dose. Med Phys 2000; 27(5): 828-37.

Sodickson A. Strategies for reducing radiation exposure in multi-detector row CT. Radiol Clin North Am 2012; 50(1): 1-14.

Liu Y, Leng S, Michalak GJ, et al. Reducing image noise in computed tomography (CT) colonography: Effect of an integrated circuit CT detector. J Comput Assist Tomogr 2014; 38(3): 398-403.

McCollough CH, Leng S, Yu L, et al. CT dose index and patient dose: they are not the same thing. Radiology 2011; 259(2): 311-316.


Refbacks

  • There are currently no refbacks.