1 / 15

Zizka J, Jandura J, Kvasnicka T, Klzo L, Grepl J Dept . of Radiology

Reduction of effective and organ dose to the eye lens in cerebral MDCT scans using iterative image reconstruction. Zizka J, Jandura J, Kvasnicka T, Klzo L, Grepl J Dept . of Radiology Charles University Teaching Hospital Hradec Kralove Czech Republic. ECR 2012.

kipp
Download Presentation

Zizka J, Jandura J, Kvasnicka T, Klzo L, Grepl J Dept . of Radiology

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Reductionofeffective and organ dose to theeyelens in cerebral MDCT scansusingiterative image reconstruction Zizka J, Jandura J, Kvasnicka T, Klzo L, Grepl J Dept. of Radiology Charles University TeachingHospital Hradec Kralove Czech Republic ECR 2012

  2. medical radiation exposure steadily rises CT accounts for > 2/3 cumulative exposure it reached the level of natural radiation background in the USA ALARA dose reduction iterative reconstruction Introduction Source: www.oecd.org

  3. Iterative reconstruction (IR) • significantly lower image noise • radiation dose reduction (25 – 60 %) FBP IR full dose 50 % dose

  4. Purpose • to compare effective radiation dose and dose to the eye lens in MDCT brain examinations utilizing either standard filtered back projection (FBP) or iterative reconstruction in image space (IRIS)

  5. Material and Methods • 400 routine adult brain CT exams: • 200 with FBP • 200 with IRIS • single source MDCT scanner • collimation: 64 x 2 x 0.6 mm • tube voltage: 120 kV (FBP & IRIS) • reference mAs: 300 (FBP) and 200 (IRIS) • rotational period 1 s • pitch 0.55 • automatic dose modulation switched on

  6. Material and Methods • recordedwere • CT Dose Index (CTDIvol) • Dose LengthProduct (DLP) • effective dose calculated by ImPACT software • organ dose to thelenswasderivedfromtheactual tube current-timeproductvalueapplied to thesliceswithlens included • image noise (SD) in a 1.5 cm2 ROI in the centrum semiovale • qualitative visual assessment: two experienced radiologists blinded to the type of image reconstruction using a visual analogue scale 1 = very low noise, optimal diagnostic quality 2 = low noise, good diagnostic quality 3 = increased noise, diagnostic quality 4 = high level noise, limited diagnostic quality 5 = unacceptable noise, non-diagnostic scan

  7. Results: radiation dose

  8. - 36 % - 58 % CTDI = 60 mGy European Commission Quality Criteria for MDCT 2004

  9. Results: image quality

  10. Image quality FBP IRIS dose reduced by 34 %

  11. Discussion ICRP ref 4825-3093-1464 https://rpop.iaea.org/RPOP/RPoP/Content/News/ICRP-statement-threshold-eye-lens.htm

  12. Discussion • eye lens radiosensitivity is higher than previously thought • the lens is frequently exposed to the primary beam in spiral MDCT scans • the organ dose to the lens leading to cataract formation (0.5 Gy) might be acquired in as low as 7 (!) non-optimized CT head scans (CTDI ≈ 60 mGy) • with optimized iterative reconstruction acquisition the number of CT head scans leading to lens opacities formation rises approx. 3-fold (20 MDCT head scans)

  13. Conclusion • even in the settings of optimized FBP based CT protocols, iterative reconstruction is capable of further substantial radiation dose savings which, in our population, further reduced both the effective and eye lens dose by more than 33 % compared to optimized FBP protocols and by 58 % compared to reference standard

More Related