Advertisement

Radiation Dose Metrics and the Effect of CT Scan Protocol Parameters

  • Sue Edyvean
  • Maria Lewis
  • Alan Britten
Part of the Medical Radiology book series (MEDRAD)

Abstract

The CT scanner consists of many hardware and software features that affect patient dose. Many of these are controlled by the user, or are implicit within organ specific scan protocols. To understand many of these features and their implications on radiation dose to the patient, it is valuable to understand the CT dose indices that are commonly used and their limitations. This chapter begins by reviewing currently used, and accepted, dose descriptors for CT scanners, and outlines some of the limitations of these parameters whilst still advocating their valid use in the description of dose characteristics of CT scanners, and specifically in the comparison of CT scan protocols. The second part of the chapter discusses the effect of the scanner and scan protocol parameters on the dose to the patient. Specifically these are separated into some key hardware features, and then parameters which are usually selectable by the user within a scan protocol. A brief description and overview of these features are given, as well as aspects of their implications on image quality.

Keywords

Image Noise Beam Width Patient Dose Dose Length Product Automatic Exposure Control 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

References

  1. American Association of Physicists in Medicine (2008) The measurement, reporting, and management of radiation dose in CT, AAPM Rep. 96, New YorkGoogle Scholar
  2. American Association of Physicists in Medicine (2010) The measurement, reporting, and management of radiation dose in CT, AAPM Rep. 111, New YorkGoogle Scholar
  3. Boone JM (2007) The trouble with CTDI 100. Med Phys 34 (4):1364–1371Google Scholar
  4. Huda W, Magill D (2011). Medical Physics, Vol. 38 (3): 1261-5Google Scholar
  5. International Electrotechnical Commission (2009) Medical electrical equipment—part 2-44 edition 3: particular requirements for basic safety and essential performance of X-ray equipment for computed tomography. IEC-60601-2-44—Edition 3, IEC GenevaGoogle Scholar
  6. Institute of Physicists and Engineers in Medicine (2003) Measurement of the performance characteristics of diagnostic systems used in medicine, report No. 32 part III Computed Tomography CT scanners, 2nd edn, YorkGoogle Scholar
  7. Jessen KA, Panzer W, Shrimpton PC (2000) EUR 16262: European guidelines on quality criteria for computed tomography. Office for Official Publications of the European Communities, LuxembourgGoogle Scholar
  8. Jones DG, Shrimpton PC (1991) Survey of CT practice in the UK. part 3: normalised organ doses calculated using monte carlo techniques. National Radiological Protection Board, OxonGoogle Scholar
  9. Leitz W, Axelsson B, Szendro G (1995) Computed tomography dose assessment: a practical approach. Radiat Prot Dosim 57:377–380Google Scholar
  10. McCollough CH, Schueler BA (2000) Calculation of effective dose. Med Phys 27(5):828–837PubMedCrossRefGoogle Scholar
  11. McCollough CH, Leng S, Yu L, Cody D, Boone J, McNitt-Gray MF (2011) CT dose index and patient dose : they are not the same thing. Radiology 259(2): 311–316Google Scholar
  12. Nakonechny KD, Fallone BG, Rathee S (2005) Novel methods of measuring single scan dose profiles and cumulative dose in CT. Med Phys 32(1):98–109PubMedCrossRefGoogle Scholar
  13. Nagel HD (2000) Radiation exposure in computed tomography—fundamentals, influencing parameters, dose assessment, optimisation, scanner data, terminology, 2nd edn. COCIR (European Coordination Committee of the Radiological and Electromedical Industries), HamburgGoogle Scholar
  14. Shrimpton PC, Hillier MC, Lewis MA, Dunn M (2005) NRPB-W67: doses from computed tomograpy (CT) examinations in the UK—2003 review. HPA, Chilcot, OxonGoogle Scholar
  15. Siegel MJ, Schmidt B, Bradley D, Suess C, Hildebolt C (2004) Radiation dose and image quality in paediatric CT: effect of technical factors and phantom size and shape. Radiology 233:515–522PubMedCrossRefGoogle Scholar
  16. Toth T, Ge Z, Daly MP (2007) How patient centering affects CT dose and noise. Med Phys 34(7):3093–3101PubMedCrossRefGoogle Scholar
  17. Taguchi T, Aradate H (1998) Med Phys 25(4):550–561PubMedCrossRefGoogle Scholar
  18. Yu et al (2011) Optimal tube potential for radiation dose reduction in paediatric CT: principles, clinical implications and pitfalls. Radiographics 31(3):835–848CrossRefGoogle Scholar
  19. Zankl M, Panzer W, Drexler G (1991) The calculation of dose from external photon exposures using reference human phantoms and Monte Carlo methods. part VI: organ doses from computed tomographic examinations: GSF—forschungszentrum fur Umwelt und Gesundtheit. Institut fur Strahlenschutz, Neuherberg, GermanyGoogle Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg 2012

Authors and Affiliations

  1. 1.Department of Physics and Clinical Engineering, St. George’s HospitalImPACT CT Scanner Evaluation CentreLondonUK

Personalised recommendations