X-ray micro-computed tomography (μCT) is a widely used imaging modality in preclinical research with applications in many areas including orthopedics, pulmonology, oncology, cardiology, and infectious disease. X-rays are a form of ionizing radiation and, therefore, can potentially induce damage and cause detrimental effects. Previous reviews have touched on these effects but have not comprehensively covered the possible implications on study results. Furthermore, interpreting data across these studies is difficult because there is no widely accepted dose characterization methodology for preclinical μCT. The purpose of this paper is to ensure in vivo μCT studies can be properly designed and the data can be appropriately interpreted.
Studies from the scientific literature that investigate the biological effects of radiation doses relevant to μCT were reviewed. The different dose measurement methodologies used in the peer-reviewed literature were also reviewed. The CT dose index 100 (CTDI100) was then measured on the Quantum GX μCT instrument. A low contrast phantom, a hydroxyapatite phantom, and a mouse were also imaged to provide examples of how the dose can affect image quality.
Data in the scientific literature indicate that scenarios exist where radiation doses used in μCT imaging are high enough to potentially bias experimental results. The significance of this effect may relate to the study outcome and tissue being imaged. CTDI100 is a reasonable metric to use for dose characterization in μCT. Dose rates in the Quantum GX vary based on the amount of material in the beam path and are a function of X-ray tube voltage. The CTDI100 in air for a Quantum GX can be as low as 5.1 mGy for a 50 kVp scan and 9.9 mGy for a 90 kVp scan. This dose is low enough to visualize bone both in a mouse image and in a hydroxyapatite phantom, but applications requiring higher resolution in a mouse or less noise in a low-contrast phantom benefit from longer scan times with increased dose.
Dose management should be considered when designing μCT studies. Dose rates in the Quantum GX are compatible with longitudinal μCT imaging.
Mitchell MJ, Logan PM (1998) Radiation-induced changes in bone. Radiographics 18:1125–1136; quiz 1242–1243
Clark DP, Badea CT (2014) Micro-CT of rodents: state-of-the-art and future perspectives. Phys Medica 30:619–634 CrossRef
Hsieh J (2009) Computed tomography: principles, design, artifacts and recent advances, 2nd edn. SPIE, Bellingham, WA
Hubbell JH, Seltzer SM (2016) Tables of X-ray Mass Attenuation Coefficients and Mass Energy-Absorption Coefficients from 1 keV to 20 MeV for Elements Z = 1 to 92 and 48 Additional Substances of Dosimetric Interest. http://www.nist.gov/pml/data/xraycoef/
Mcnitt-Gray MF (2004) Tradeoffs in Image Quality and Radiation Dose for CT. In: AAPM 46th Annu. Meet. Pittsburgh, PA, p 2328
Jermoumi M, Korideck H, Bhagwat M et al (2015) No comprehensive quality assurance phantom for the small animal radiation research platform (SARRP). Phys Medica 31:529–535 CrossRef
Jeggo P, Löbrich M (2006) Radiation-induced DNA damage responses. Radiat Prot Dosim 122:124–127 CrossRef
Budach W, Hartford A, Gioioso D et al (1992) Tumors arising in SCID mice share enhanced radiation sensitivity of SCID normal tissues. Cancer Res 52:6292–6296 PubMed
Lee CJ, Spalding AC, Ben-Josef E et al (2010) In vivo bioluminescent imaging of irradiated orthotopic pancreatic cancer xenografts in nonobese diabetic-severe combined immunodeficient mice: a novel method for targeting and assaying efficacy of ionizing radiation. Transl Oncol 3:153–159 CrossRefPubMedPubMedCentral
Nowosielska EM, Cheda A, Wrembel-Wargocka J, Janiak MK (2010) Immunological mechanism of the low-dose radiation-induced suppression of cancer metastases in a mouse model. Dose-Response 8:209–226 CrossRef
International Commission on Radiation Units and Measurements (2012) ICRU Report No. 87: radiation dose and image-quality assessment in computed tomography. J ICRU 12:1–149
AAPM Task Group 2 (1993) Specification and Acceptance Testing of Computed Tomography Scanners. AAPM Rep. 39
AAPM Task Group 23 (2008) The Measurement, Reporting, and Management of Radiation Dose in CT. AAPM Rep. NO. 96
AAPM Task Group 3 (2010) Comprehensive Methodology for the Evaluation of Radiation Dose in X-ray Computed Tomography. AAPM Rep. 111
Bazalova M, Graves E (2016) MicroCT dose and image quality for in vivo microCT systems. Unpubl. data
Obenaus A, Smith A (2004) Radiation dose in rodent tissues during micro-CT imaging. J X-Ray Sci Technol 12:241–249
Johns HE, Cunningham JR (1969) The Physics of Radiology, 3rd ed. Thomas
US Food and Drug Administration (2016) What are the Radiation Risks from CT? http://www.fda.gov/Radiation-EmittingProducts/RadiationEmittingProductsandProcedures/MedicalImaging/MedicalX-Rays/ucm115329.htm
Feldkamp LA, Davis LC, Kress JW (1984) Practical cone-beam algorithm. J Opt Soc Am A 1:612 CrossRef
Image Wisely (2016) Radiation Safety in Adult Medical Imaging. http://www.imagewisely.org/
Image Gently (2014) The Alliance for Radiation in Pediatric Imaging. http://www.imagegently.org/
Bretin F, Warnock G, Luxen A et al (2013) Performance evaluation and X-ray dose quantification for various scanning protocols of the GE eXplore 120 micro-CT. IEEE Trans Nucl Sci 60:3235–3241 CrossRef
- Dosimetry in Micro-computed Tomography: a Review of the Measurement Methods, Impacts, and Characterization of the Quantum GX Imaging System
Jeffrey A. Meganck
- Springer US
Neu im Fachgebiet Radiologie
Meistgelesene Bücher aus der Radiologie
e.Med Kampagnen-Visual, Mail Icon II