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C van Kuijk

Publications and source records attributed to C van Kuijk.

15 recordsLinked to original sources
PubMed1992

Influence of calibration materials in single- and dual-energy quantitative CT.

With single-energy (SE) quantitative computed tomography (CT), the density of bone mineral in the vertebral body can be estimated. With dual-energy (DE) quantitative CT, both bone-mineral density and fat content can be measured. The calibration device normally used contains materials mimicking trabecular bone, fat, and hematopoietic tissue. To evaluate the influence of different calibration materials on these estimates, theoretical CT numbers were calculated for the trabecular part of the vertebral body and for different calibration devices. Calibration devices were simulated; they contained either identical materials or various accepted tissue-mimicking materials. For all combinations, quantitative CT data were generated for the SE quantitative CT method and for two DE quantitative CT methods. Only one method provided accurate results under ideal circumstances. The selection of tissue-mimicking materials in the calibration devices is important for the interpretation of results of SE and DE quantitative CT. Errors of more than a factor 2 were found when different types of materials were used.

Absorptiometry, Photon↗
PubMed1990

Evaluation of postprocessing dual-energy methods in quantitative computed tomography. Part 1. Theoretical considerations.

Five postprocessing methods for dual-energy quantitative computed tomography of the vertebral body were evaluated theoretically. The methods were compared by transforming the original sets of equations to a standard set. Only two of these methods produced optimal results, namely the basic approach of Goodsitt et al and the method of Nickoloff et al. The calibration approach of Goodsitt et al will produce optimal results only if calibration materials are available that mimic the anatomic constituents of the vertebral body better than those available currently. Theoretically, the methods of Cann et al and of Laval-Jeantet et al will not produce optimal results.

Bone Density↗
PubMed1990

Evaluation of postprocessing dual-energy methods in quantitative computed tomography. Part 2. Practical aspects.

Three facets of dual-energy quantitative computed tomography are studied: (1) the algorithm for postprocessing data (the methods of Cann, Laval-Jeantet et al, Goodsitt et al [two methods], and Nickoloff et al); (2) the influence of choice of tissue-equivalent materials for calibration; and (3) the difference between central and peripheral calibration. The different tissue-equivalent materials include bone mineral-equivalent (K2HPO4 solutions and calcium hydroxyapatite), fat-equivalent (liquid paraffin, polyethylene, and 70% ethanol solution), and red marrow-equivalent (plastic). Deviation from the manufacturer's quoted content is least with central positioning of the calibration materials. The accuracy of estimates is best when the same tissue-equivalent materials are used for calibration that are being measured. The deviations produced by the use of different tissue-equivalent materials indicate the importance of using materials that mimic the components of bone most closely. The two methods of Goodsitt et al and the method of Nickoloff et al produced the best results.

Algorithms↗
PubMedDate not supplied

Selection of fat-equivalent materials in postprocessing dual-energy quantitative CT.

Postprocessing dual-energy QCT is supposed to be able to predict the bone mineral more accurately than single-energy QCT. In addition, the fat content in the vertebral body can be determined. To this aim, some methods include fat-equivalent materials in the calibration device. However, the choice of an appropriate fat-equivalent material is difficult. To solve this selection problem, a method has been developed in which the x-ray interactions of tissue are characterized by three energy-independent parameters. For five different known constituents of anatomical fat, fat-equivalent materials are evaluated. It is shown that it is not possible to find one fat-equivalent material for all anatomical fat compositions. For this reason, the influence of a mismatch between the characterization parameters of anatomical fat compositions and fat-equivalent materials has been evaluated. It is shown that a mismatch in tissue characterization parameters can result in deviations of 10% in the bone mineral content and more than 300% in the estimated fat contents.

Adipose Tissue↗