Accurate assessment of mineral density (MD) provides information critical to the understanding of mineralization processes of calcified tissues, including bones and teeth. High-resolution three-dimensional assessment of the MD of teeth has been demonstrated by relatively inaccessible synchrotron radiation microcomputed tomography (SRµCT). While conventional desktop µCT (CµCT) technology is widely available, polychromatic source and cone-shaped beam geometry confound MD assessment. Recently, considerable attention has been given to optimizing quantitative data from CµCT systems with polychromatic x-ray sources. In this review, we focus on the approaches that minimize inaccuracies arising from beam hardening, in particular, beam filtration during the scan, beam-hardening correction during reconstruction, and mineral density calibration. Filtration along with lowest possible source voltage results in a narrow and near-single-peak spectrum, favoring high contrast and minimal beam-hardening artifacts. More effective beam monochromatization approaches are described. We also examine the significance of beam-hardening correction in determining the accuracy of mineral density estimation. In addition, standards for the calibration of reconstructed grey-scale attenuation values against MD, including K2PHO4 liquid phantom, and polymer-hydroxyapatite (HA) and solid hydroxyapatite (HA) phantoms, are discussed.
AndersonPElliottJCBoseUJonesSJ (1996). A comparison of the mineral content of enamel and dentine in human premolars and enamel pearls measured by x-ray microtomography. Arch Oral Biol41:281-290.
2.
AngkerLNockoldsCSwainMVKilpatrickN (2004). Quantitative analysis of the mineral content of sound and carious primary dentine using BSE imaging. Arch Oral Biol49:99-107.
3.
AngmarBCarlstromDGlasJE (1963). Studies on the ultrastructure of dental enamel. IV. The mineralization of normal human enamel. J Ultrastruct Res8:12-23.
BarrettJFKeatN (2004). Artifacts in CT: recognition and avoidance. Radiographics24:1679-1691.
6.
BernhardtRScharnweberDMullerBThurnerPSchliephakeHWyssP. (2004). Comparison of microfocus- and synchrotron x-ray tomography for the analysis of osteointegration around Ti6A14V implants. Eur Cell Mater7:42-51.
7.
BoBZhouSLiL (2001). [Relations of mechanical properties of human mandible to strain rate and density under tension load]. Zhonghua Kou Qiang Yi Xue Za Zhi36:8-10 [in Chinese].
8.
BoivinGMeunierPJ (2002). The degree of mineralization of bone tissue measured by computerized quantitative contact microradiography. Calcif Tissue Int70:503-511.
BonseUBuschFGunnewigOBeckmannFPahlRDellingG. (1994). 3D computed x-ray tomography of human cancellous bone at 8 microns spatial and 10(-4) energy resolution. Bone Miner25:25-38.
11.
BurghardtAJKazakiaGJLaibAMajumdarS (2008). Quantitative assessment of bone tissue mineralization with polychromatic micro-computed tomography. Calcif Tissue Int83:129-138.
12.
ButzFOgawaTChangTLNishimuraI (2006). Three-dimensional bone-implant integration profiling using micro-computed tomography. Int J Oral Maxillofac Implants21:687-695.
13.
ChappardCBasillaisABenhamouLBonassieABrunet-ImbaultBBonnetN. (2006). Comparison of synchrotron radiation and conventional x-ray microcomputed tomography for assessing trabecular bone microarchitecture of human femoral heads. Med Phys33:3568-3577.
14.
ChengJCQinLCheungCSSherAHLeeKMNgSW. (2000). Generalized low areal and volumetric bone mineral density in adolescent idiopathic scoliosis. J Bone Miner Res15:1587-1595.
15.
ChuehHSTsaiWKFuHMChenJC (2006). Evaluation of the quantitative capability of a home-made cone-beam micro computed tomography system. Comput Med Imaging Graph30:349-355.
16.
Clementino-LuedemannTNKunzelmannKH (2006). Mineral concentration of natural human teeth by a commercial micro-CT. Dent Mater J25:113-119.
17.
Clementino-LuedemannTNDabanogluAIlieNHickelRKunzelmannKH (2006). Micro-computed tomographic evaluation of a new enzyme solution for caries removal in deciduous teeth. Dent Mater J25:675-683.
18.
DaculsiGKerebelBLe CabellecMTKerebelLM (1979). Qualitative and quantitative data on arrested caries in dentine. Caries Res13:190-202.
19.
DaculsiGLeGerosRZJeanAKerebelB (1987). Possible physico-chemical processes in human dentin caries. J Dent Res66:1356-1359.
20.
DavisGRElliottJC (2003). High definition x-ray microtomography using a conventional impact X-ray source. J Phys IV France104:131-134.
21.
DavisGRWongFS (1996). X-ray microtomography of bones and teeth. Physiol Meas17:121-146.
22.
de Josselin de JongEten BoschJJ (1985). Error analysis of the microradiographic determination of mineral content in mineralised tissue slices. Phys Med Biol30:1067-1075.
23.
De ManBNuytsJDupontPMarchalGSuetensP (1999). Metal streak artifacts in x-ray computed tomography: a simulation study. IEEE Trans Nuclear Sci46:691-696.
24.
De ManBNuytsJDupontPMarchalGSuetensP (2000). Reduction of metal streak artifacts in x-ray computed tomography using a transmission maximum a posteriori algorithm. IEEE Trans Nuclear Sci47:977-981.
25.
De ManBNuytsJDupontPMarchalGSuetensP (2001). An iterative maximum-likelihood polychromatic algorithm for CT. IEEE Trans Med Imaging20:999-1008.
26.
DowkerSEElliottJCDavisGRWassifHS (2003). Longitudinal study of the three-dimensional development of subsurface enamel lesions during in vitro demineralisation. Caries Res37:237-245.
27.
DowkerSEElliottJCDavisGRWilsonRMCloetensP (2004). Synchrotron x-ray microtomographic investigation of mineral concentrations at micrometre scale in sound and carious enamel. Caries Res38:514-522.
ElliottJCDowkerSEKnightRD (1981). Scanning x-ray microradiography of a section of a carious lesion in dental enamel. J Microsc123(Pt 1):89-92.
30.
ElliottJCWongFSAndersonPDavisGRDowkerSE (1998). Determination of mineral concentration in dental enamel from x-ray attenuation measurements. Connect Tissue Res38:61-72.
31.
FaulknerKGGluerCCGramppSGenantHK (1993). Cross-calibration of liquid and solid QCT calibration standards: corrections to the UCSF normative data. Osteoporos Int3:36-42.
32.
FeldkampLADavisLCKressJW (1984). Practical cone-beam algorithm. J Opt Soc Am A1:612-619.
33.
FolletHBoivinGRumelhartCMeunierPJ (2004). The degree of mineralization is a determinant of bone strength: a study on human calcanei. Bone34:783-789.
34.
GoodsittMM (1992). Conversion relations for quantitative CT bone mineral densities measured with solid and liquid calibration standards. Bone Miner19:145-158.
35.
GrassMKohlerTProksaR (2000). 3D cone-beam CT reconstruction for circular trajectories. Phys Med Biol45:329-347.
HeLHStandardOCHuangTTLatellaBASwainMV (2007). Mechanical behaviour of porous hydroxyapatite. Acta Biomater4:577-586.
38.
HuangTTJonesASHeLHDarendelilerMASwainMV (2007). Characterisation of enamel white spot lesions using x-ray micro-tomography. J Dent35:737-743.
39.
JenningsRJ (1988). A method for comparing beam-hardening filter materials for diagnostic radiology. Med Phys15:588-599.
40.
JohnsonMWTaylorBRBermanDS (1969). The response of deciduous dentine to caries studied by correlated light and electron microscopy. Caries Res3:348-368.
41.
JosephPMSpitalRD (1978). A method for correcting bone induced artifacts in computed tomography scanners. J Comput Assist Tomogr2:100-108.
42.
KawasakiKRubenJStokroosITakagiOArendsJ (1999). The remineralization of EDTA-treated human dentine. Caries Res33:275-280.
43.
KazakiaGJBurghardtAJCheungSMajumdarS (2008). Assessment of bone tissue mineralization by conventional x-ray microcomputed tomography: comparison with synchrotron radiation microcomputed tomography and ash measurements. Med Phys35:3170-3179.
44.
KinneyJHNicholsMC (1992). X-ray tomographic microscopy (XTM) using synchrotron radiation. Ann Rev Mater Sci22:121-152.
45.
KinneyJHMarshallGWJrMarshallSJ (1994). Three-dimensional mapping of mineral densities in carious dentin: theory and method. Scanning Microsc8:197-204.
46.
KlontBten CateJM (1991). Remineralization of bovine incisor root lesions in vitro: the role of the collagenous matrix. Caries Res25:39-45.
47.
LeeHSBergJHGarcia-GodoyFJangKT (2008). Long-term evaluation of the remineralization of interproximal caries-like lesions adjacent to glass-ionomer restorations: a micro-CT study. Am J Dent21:129-132.
48.
LewisR (1997). Medical applications of synchrotron radiation x-rays. Phys Med Biol42:1213-1243.
49.
LindeABhownMButlerWT (1980). Noncollagenous proteins of dentin. A re-examination of proteins from rat incisor dentin utilizing techniques to avoid artifacts. J Biol Chem255:5931-5942.
MagneP (2007). Efficient 3D finite element analysis of dental restorative procedures using micro-CT data. Dent Mater23:539-548.
52.
MarshallGWJrMarshallSJKinneyJHBaloochM (1997). The dentin substrate: structure and properties related to bonding. J Dent25:441-458.
53.
MarshallGWJrChangYJGanskySAMarshallSJ (2001). Demineralization of caries-affected transparent dentin by citric acid: an atomic force microscopy study. Dent Mater17:45-52.
54.
MeganckJAKozloffKMThorntonMMBroskiSMGoldsteinSA (2009). Beam hardening artifacts in micro-computed tomography scanning can be reduced by x-ray beam filtration and the resulting images can be used to accurately measure BMD. Bone45:1104-1116.
55.
MukaiYten CateJM (2002). Remineralization of advanced root dentin lesions in vitro. Caries Res36:275-280.
56.
MukaiYLagerweijMDten CateJM (2001). Effect of a solution with high fluoride concentration on remineralization of shallow and deep root surface caries in vitro. Caries Res35:317-324.
57.
MulderLKoolstraJHVan EijdenTM (2004). Accuracy of microCT in the quantitative determination of the degree and distribution of mineralization in developing bone. Acta Radiol45:769-777.
58.
NazarianASnyderBDZurakowskiDMullerR (2008). Quantitative micro-computed tomography: a non-invasive method to assess equivalent bone mineral density. Bone43:302-311.
59.
NuzzoSLafage-ProustMHMartin-BadosaEBoivinGThomasTAlexandreC. (2002a). Synchrotron radiation microtomography allows the analysis of three-dimensional microarchitecture and degree of mineralization of human iliac crest biopsy specimens: effects of etidronate treatment. J Bone Miner Res17:1372-1382.
60.
NuzzoSPeyrinFCloetensPBaruchelJBoivinG (2002b). Quantification of the degree of mineralization of bone in three dimensions using synchrotron radiation microtomography. Med Phys29:2672-2681.
61.
ParkCSwainMDuncanW (2009). Micro-computerised tomography optimisation for the measurement of bone mineral density around titanium dental implants. J Biomech Sci Eng (Spec Iss, 4th Asian Pacific Conference on Biomechanics) 5:2-10.
62.
PaschalisEPBettsFDiCarloEMendelsohnRBoskeyAL (1997). FTIR microspectroscopic analysis of normal human cortical and trabecular bone. Calcif Tissue Int61:480-486.
63.
PostnovAAVinogradovAVVan DyckDSavelievSVDe ClerckNM (2003). Quantitative analysis of bone mineral content by x-ray microtomography. Physiol Meas24:165-178.
64.
RebaudiAKollerBLaibATrisiP (2004). Microcomputed tomographic analysis of the peri-implant bone. Int J Periodontics Restorative Dent24:316-325.
65.
RhoJYHobathoMCAshmanRB (1995). Relations of mechanical properties to density and CT numbers in human bone. Med Eng Phys17:347-355.
66.
RiceJCCowinSCBowmanJA (1988). On the dependence of the elasticity and strength of cancellous bone on apparent density. J Biomech21:155-168.
67.
RitmanEL (2004). Micro-computed tomography—current status and developments. Annu Rev Biomed Eng6:185-208.
68.
RoschgerPFratzlPEschbergerJKlaushoferK (1998). Validation of quantitative backscattered electron imaging for the measurement of mineral density distribution in human bone biopsies. Bone23:319-326.
69.
RyderWJOttRJLeesJEKeayABassfordDFraserGW (2002). Detector characteristics of CCDs for high resolution gamma ray imaging. Nuclear Science Symposium Conference Record IEEE2:687-689.
70.
SanadaSKawaharaKYamamotoTTakashimaT (1999). New tissue substitutes representing cortical bone and adipose tissue in quantitative radiology. Phys Med Biol44:N107-N112.
71.
SchulzeRKBerndtDd’HoedtB (2010). On cone-beam computed tomography artifacts induced by titanium implants. Clin Oral Implants Res21:100-107.
72.
SchwassDRSwainMVPurtonDGLeichterJW (2009). A system of calibrating microtomography for use in caries research. Caries Res43:314-321.
73.
SchweizerSHattendorfBSchneiderPAeschlimannBGaucklerLMullerR. (2007). Preparation and characterization of calibration standards for bone density determination by micro-computed tomography. Analyst132:1040-1045.
74.
SmithCBSmithDA (1976). Relations between age, mineral density and mechanical properties of human femoral compacta. Acta Orthop Scand47:496-502.
75.
StoppieNvan der WaerdenJPJansenJADuyckJWeversMNaertIE (2005). Validation of microfocus computed tomography in the evaluation of bone implant specimens. Clin Implant Dent Relat Res7:87-94.
76.
ten BoschJJAngmar-MånssonB (1991). A review of quantitative methods for studies of mineral content of intra-oral caries lesions. J Dent Res70:2-14.
77.
ten CateJM (2001). Remineralization of caries lesions extending into dentin. J Dent Res80:1407-1411.
78.
ten CateJMNyvadBVan de Plassche-SimonsYMFejerskovO (1991). A quantitative analysis of mineral loss and shrinkage of in vitro demineralized human root surfaces. J Dent Res70:1371-1374.
79.
TuckerDMBarnesGTChakrabortyDP (1991). Semiempirical model for generating tungsten target x-ray spectra. Med Phys18:211-218.
van der VeenMHten BoschJJ (1996). The influence of mineral loss on the auto-fluorescent behaviour of in vitro demineralised dentine. Caries Res30:93-99.
82.
van StrijpAJBuijsMJten CateJM (1995). Contact microradiography of dentine under wet conditions to prevent lesion shrinkage. Caries Res29:107-110.
83.
VerdelisKCrenshawMAPaschalisEPDotySAttiEBoskeyAL (2003). Spectroscopic imaging of mineral maturation in bovine dentin. J Dent Res82:697-702.
84.
WangGLinTHChengPShinozakiDM (1993). A general cone-beam reconstruction algorithm. IEEE Trans Med Imaging12:486-496.
85.
WeatherellJARobinsonCHallsworthAS (1974). Variations in the chemical composition of human enamel. J Dent Res53:180-192.
WillmottNSWongFSDavisGR (2007). An x-ray microtomography study on the mineral concentration of carious dentine removed during cavity preparation in deciduous molars. Caries Res41:129-134.
88.
WittRMCameronJR (1970). An improved bone standard containing dipotassium hydrogen phosphate solution for the intercomparison of different bone scanning systems. Report No. AEC COO-1422–78. Washington, DC: US Atomic Energy Commission.
89.
WongFSElliottJCAndersonPDavisGR (1995). Mineral concentration gradients in rat femoral diaphyses measured by x-ray microtomography. Calcif Tissue Int56:62-70.
90.
WongFSElliottJCDavisGRAndersonP (2000). X-ray microtomographic study of mineral distribution in enamel of mandibular rat incisors. J Anat196(Pt 3):405-413.
91.
WongFSAndersonPFanHDavisGR (2004). X-ray microtomographic study of mineral concentration distribution in deciduous enamel. Arch Oral Biol49:937-944.
92.
WongFSWillmottNSDavisGR (2006). Dentinal carious lesion in three dimensions. Int J Paediatr Dent16:419-423.
93.
ZavgorodniyAVRohanizadehRBulcockSSwainMV (2008a). Ultrastructural observations and growth of occluding crystals in carious dentine. Acta Biomater4:1427-1439.
94.
ZavgorodniyAVRohanizadehRSwainMV (2008b). Ultrastructure of dentine carious lesions. Arch Oral Biol53:124-132.
95.
ZhangYZhangLZhuXRLeeAKChambersMDongL (2007). Reducing metal artifacts in cone-beam CT images by preprocessing projection data. Int J Radiat Oncol Biol Phys67:924-932.
96.
ZhengLHiltonJFHabelitzSMarshallSJMarshallGW (2003). Dentin caries activity status related to hardness and elasticity. Eur J Oral Sci111:243-252.
97.
ZhengYLuWWZhuQQinLZhongSLeongJC (2000). Variation in bone mineral density of the sacrum in young adults and its significance for sacral fixation. Spine25:353-357.
98.
ZouWGaoJJonesASHunterNSwainMV (2009). Characterization of a novel calibration method for mineral density determination of dentine by x-ray micro-tomography. Analyst134:72-79.
