JBiSE  Vol.5 No.12 A , December 2012
Phantom study of the impact of adaptive statistical iterative reconstruction (ASiRTM) on image quality for paediatric computed tomography

Quantitative analysis of image quality will be helpful for designing ASiRTM-enhanced paediatric CT protocols, balancing image quality and radiation dose. Catphan600 phantom studies were performed on a GE Discovery HD750 64-slice CT scanner. Images were reconstructed with 0% - 100% ASiRTM (tube current 150 mA, variable kVp 80 - 140) in order to determine the optimal ASiRTM-Filtered Back Projection (FBP) blend. Images reconstructed with a 50% ASiRTM-50% FBP blend were compared to FBP images (0% ASiRTM) over a wide range of kVp (80 - 140) and mA (10 - 400) values. Measurements of image noise, CT number accuracy and uniformity, spatial and contrast resolution, and low contrast detectability were performed on axial and reformatted coronal images. Improvements in CNR, low contrast detectability and radial uniformity were observed in ASiRTM images compared to FBP images. 50% ASiRTM was associated with a 26% - 30% reduction in image noise. Changes in noise texture were observed at higher % ASiRTM blends with impact on visualisation of low and high contrast objects. A small decrease in limiting spatial resolution was detected with addition of ASiRTM, more appreciable at very low tube currents. The preferred blend for paediatric body protocols in our study, as determined by the image quality parameters investigated, was 50% ASiRTM when used with tube currents greater than 50 mA.

Cite this paper: Protik, A. , Thomas, K. , Babyn, P. and Ford, N. (2012) Phantom study of the impact of adaptive statistical iterative reconstruction (ASiRTM) on image quality for paediatric computed tomography. Journal of Biomedical Science and Engineering, 5, 793-806. doi: 10.4236/jbise.2012.512A100.

[1]   Mettler Jr., F.A., Wiest, P.W., Locken, J.A., et al. (2000) CT scanning: Patterns of use and dose. Journal of Radiological Protection, 20, 353-359. doi:10.1088/0952-4746/20/4/301

[2]   ICRP (2007) Radiological protection in medicine. ICRP Publication, Annual ICRP, 37. Publication 105

[3]   Kalra, M.K., Maher, M.M., Sahani, D.V., et al. (2003) Low-dose CT of the abdomen: Evaluation of image improvement with use of noise reduction filters pilot study. Radiology, 228, 251-256. doi:10.1148/radiol.2281020693

[4]   Leipsic, J., Nguyen, G., Brown, J., et al. (2010) A prospective evaluation of dose reduction and image quality in chest CT using adaptive statistical iterative reconstruction. American Journal of Roentgenology, 195, 1095- 1099. doi:10.2214/AJR.09.4050

[5]   Leipsic, J., Labounty, T.M., Heilbron, B., et al. (2010) Adaptive statistical iterative reconstruction: Assessment of image noise and image quality in coronary CT angio-graphy. American Journal of Roentgenology, 195, 649-654. doi:10.2214/AJR.10.4285

[6]   Marin, D., Nelson, R.C., Schindera, S.T., et al. (2010) Low-tube-voltage, high-tube-current multidetector abdo- minal CT: Improved image quality and decreased radia- tion dose with adaptive statistical iterative reconstruction algorithm—Initial clinical experience. Radiology, 254, 145-153. doi:10.1148/radiol.09090094

[7]   Hara, A.K., Paden, R.G., Silva, A.C., et al. (2009) Iterative reconstruction technique for reducing body radiation dose at CT: Feasibility study. American Journal of Roent- genology, 193, 764-771. doi:10.2214/AJR.09.2397

[8]   Silva, A.C., Lawder, H.J., Hara, A., et al. (2010) Innovations in CT dose reduction strategy: Application of the adaptive statistical iterative reconstruction algorithm. American Journal of Roentgenology, 194, 191-199. doi:10.2214/AJR.09.2953

[9]   Mieville, F.A., Gudinchet, F., Rizzo, E., et al. (2011) Pa- ediatric cardiac CT examinations: Impact of the iterative reconstruction method ASIR on image quality—Preliminary findings. Pedatric Radiology, 41, 1154-1164. doi:10.1007/s00247-011-2146-8

[10]   National Research Council (2006) Health risks from exposure to low levels of ionizing radiation: BEIR VII phase 2. The National Academies Press, Washington DC.

[11]   The Phantom Laboratory (2012) Catphan 500 - 600 Manual. The Phantom Laboratory, Salem.

[12]   Boedeker, K.L., Cooper, V.N. and McNitt-Gray, M.F. (2007) Application of the noise power spectrum in modern diagnostic MDCT: Part I. Measurement of noise power spectra and noise equivalent quanta. Physics in Medicine and Biology, 52, 4027-4046. doi:10.1088/0031-9155/52/14/002

[13]   Sande, E.P., Martinsen, A.C., Hole, E.O., et al. (2010) Interphantom and interscanner variations for Hounsfield units—Establishment of reference values for HU in a commercial QA phantom. Physics in Medicine and Biol- ogy, 55, 5123-5135. doi:10.1088/0031-9155/55/17/015

[14]   Shikhaliev, P.M. (2010) The upper limits of the SNR in radiography and CT with polyenergetic X-rays. Physics in Medicine and Biology, 55, 5317-5139. doi:10.1088/0031-9155/55/18/005

[15]   Hanson, K.M. (1979) Detectability in computed tomogramphic images. Medical Physics, 6, 441-451. doi:10.1118/1.594534

[16]   Samei, E., Christianson, O., Chen, J., et al. (2012) TH- E-217BCD-09: Task-based image quality of CT iterative reconstruction across three commercial implementations. Medical Physics, 39, 4016-4016. doi:10.1118/1.4736383

[17]   Solomon, J., Christianson, O. and Samei, E. (2012) TH- E-217BCD-07: Quantitative comparison of noise texture across ct scanners from different vendors. Medical Physics, 39, 4016-4016. doi:10.1118/1.4736381

[18]   Brady, S. and Kaufman, R. (2011) WE-A-301-01: Characterization of an adaptive statistical iterative reconstruction (ASiRTM) algorithm in CT: A pediatric perspective. Medical Physics, 38, 3795-3796. doi:10.1118/1.3613285

[19]   Singh, S., Kalra, M.K., Hsieh, J., et al. (2010) Abdominal CT: Comparison of adaptive statistical iterative and filtered back projection reconstruction techniques. Radiology, 257, 373-383. doi:10.1148/radiol.10092212

[20]   Boedeker, K.L. and McNitt-Gray, M.F. (2007) ApplicaTion of the noise power spectrum in modern diagnostic MDCT: Part II. Noise power spectra and signal to noise. Physics in Medicine and Biology, 52, 4047-4061. doi:10.1088/0031-9155/52/14/003

[21]   Richard, S., Husarik, D.B., Yadava, G., et al. (2012) Towards task-based assessment of CT performance: System and object MTF across different reconstruction algorithms. Medical Physics, 39, 4115-4122. doi:10.1118/1.4725171