A low-radiation exposure protocol for 3D QCT of the spine
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Cadaver and phantom measurements and simulations confirmed that radiation exposure in 3D QCT of the spine can be reduced if 80 kV instead of 120 kV protocols are used; 120 mAs and slice thicknesses of 1–1.3 mm should be usable but obese patient will require higher milliampere-second settings.
To develop a low-radiation exposure CT acquisition protocol for 3D QCT of the thoracolumbar spine.
Twenty-six cadavers were scanned with a standard protocol of 120 kV, 100 mAs and with a low-dose protocol using 90 kV, 150 mAs. The scan range included the vertebrae T6 to L4. Each vertebra was segmented and the integral volume and BMD of the total vertebral body were determined. Effective dose values were estimated. The impact of milliampere-second reduction on image quality was simulated by adding noise.
One hundred ninety-six vertebrae were analyzed. Integral volume as well as integral BMD correlated significantly (p < 0.001) between standard and low-dose protocols (volume, r 2 = 0.991, residual root mean square (RMS) error, 0.77 cm3; BMD, r 2 = 0.985, RMS error, 4.21 mg/cm3). The slope significantly differed from 1 for integral BMD but not for volume hinting at residual field inhomogeneity differences between the two voltage settings that could be corrected by cross-calibration. Compared to the standard protocol, effective dose was reduced by over 50 % in the low-dose protocol. Adding noise in the 90 kV images to simulate a reduction from 150 to 100 mAs did not affect the results for integral volume or BMD.
For 3D QCT of the spine, depending on scanner type, 80 or 90 kV instead of 120 kV protocols may be considered as an important option to reduce radiation exposure; 120 mAs and slice thicknesses of 1–1.5 mm are usable if segmentation is robust to noise. In obese patients, higher milliampere-second settings will be required.
Keywords3D QCT Effective dose Radiation exposure Spine X-ray tube voltage
This project was supported by the German Federal Ministry of Education and Research (BMBF, BioAsset 01EC1005D).
Conflicts of Interest
- 1.Engelke K, Adams JE, Armbrecht G, Augat P, Bogado CE, Bouxsein ML, Felsenberg D, Ito M, Prevrhal S, Hans DB, Lewiecki EM (2008) Clinical use of quantitative computed tomography and peripheral quantitative computed tomography in the management of osteoporosis in adults: the 2007 ISCD official positions. J Clin Densitom 11(1):123–162PubMedCrossRefGoogle Scholar
- 2.Lewiecki EM, Keaveny TM, Kopperdahl DL, Genant HK, Engelke K, Fuerst T, Kivitz A, Davies RY, Fitzpatrick LA (2009) Once-monthly oral ibandronate improves biomechanical determinants of bone strength in women with postmenopausal osteoporosis. J Clin Endocrinol Metab 94(1):171–180PubMedCrossRefGoogle Scholar
- 3.Brixen, K., R. Chapurlat, A.M. Cheung, T.M. Keaveny, T. Fuerst, K. Engelke, R. Recker, B. Dardzinski, N. Verbruggen, S. Ather, E. Rosenberg, and A.E. de Papp (2013) Bone density, turnover, and estimated strength in postmenopausal women treated with odanacatib: a randomized trial. J Clin Endocrinol Metab, 2013/01/23Google Scholar
- 5.Glüer, C.-C., M. Krause, O. Museyko, B. Wulff, G. Campbell, T. Damm, M. Daugshies, G. Huber, Y. Lu, J. Pena, S. Waldhausen, J. Bastgen, K. Rohde, I. Steinebach, F. Thomsen, M. Amling, R. Barkmann, K. Engelke, M. Morlock, J. Pfeilschifter, and K. Püschel, New horizons for the in vivo assessment of major aspects of bone quality: microstructure and material properties assessed by Quantitative Computed Tomography and Quantitative Ultrasound methods developed by the BioAsset consortium. Osteologie, submittedGoogle Scholar
- 7.Funama Y, Awai K, Nakayama Y, Kakei K, Nagasue N, Shimamura M, Sato N, Sultana S, Morishita S, Yamashita Y (2005) Radiation dose reduction without degradation of low-contrast detectability at abdominal multisection CT with a low-tube voltage technique: phantom study. Radiology 237(3):905–910, 2005/10/21PubMedCrossRefGoogle Scholar
- 10.Murakami Y, Kakeda S, Kamada K, Ohnari N, Nishimura J, Ogawa M, Otsubo K, Morishita Y, Korogi Y (2010) Effect of tube voltage on image quality in 64-section multidetector 3D CT angiography: Evaluation with a vascular phantom with superimposed bone skull structures. AJNR Am J Neuroradiol 31(4):620–625, 2009/11/28PubMedCrossRefGoogle Scholar
- 14.Zankl, M., W. Panzer, and G. Drexler (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, MunichGoogle Scholar
- 15.ICRP, The 2007 Recommendations of the International Commission on Radiological Protection, ICRP 103. Ann ICRP, 2007. 37(2–4)Google Scholar
- 23.Nakayama Y, Awai K, Funama Y, Hatemura M, Imuta M, Nakaura T, Ryu D, Morishita S, Sultana S, Sato N, Yamashita Y (2005) Abdominal CT with low tube voltage: preliminary observations about radiation dose, contrast enhancement, image quality, and noise. Radiology 237(3):945–951, 2005/10/21PubMedCrossRefGoogle Scholar