SummaryThe aim of this work was to present and discuss a quality control protocol for in vitro micro-computed tomography (microCT), based on the adaptation of the quality control protocols for medical computed tomography. The importance of establishing a quality control protocol is related to the opportunity to identify problems on time comparing the microCT images acquired in different time points, and in this way to verify the performance of the device. The proposed quality control protocol was applied for a long-time monitoring period to verify the stability of the micro-tomographic system over time. The protocol proposed in this study was applied to the histomorphometric characterization of bone tissue, but it can be used on a wide range of in vitro microCT applications. Noise and uniformity tests, taken and adapted to micro-tomographic system by medical standard guidelines of quality control, were performed by the use of a water phantom. An accuracy test was designed and performed by the use of a morphometric calibrated phantom. All these tests were performed during a long-time monitoring period to control the stability of the system. Specific control charts and monitoring parameters for each test were used to represent the monthly measures collected during 20 months and an out of control condition was defined. The reference values (baseline), calculated to control the stability of micro-tomographic system over time, were calculated during acceptance/status test. During the period, no out of control conditions in noise, uniformity and accuracy tests were recorded. However, a changing condition was found in noise test, as showed by using statistical C (P < 0.01) and Kruskal-Wallis (P < 0.05) tests. In particular, a Wilcoxon rank sum test with Bonferroni correction (P < 0.0125) was applied in noise test to investigate which of the comparisons among first five acquisitions of year 2004 (group B.L.) and each group was significant

Micro-computed tomography (micro-CT) is widely used for in vitro studies to characterize bone structure at the resolution of 10–100 microns. However, a densitometric calibration protocol is necessary to convert the X-ray attenuation coefficient provided by micro-CT in bone mineral density (BMD). The lastest one has an important role to improve the accuracy of subject-specific finite element models. This work presents a simple calibration protocol based on the use of solid hydroxyapatite phantoms with the correction of the beam hardening effect. The method was validated in comparison to ashing measures of cortical and trabecular human bone. In addition, bone samples tissue mineral density (TMD) was calculated with two different methods. The correlation between ash density and BMD was linear both for cortical ([Formula: see text]) and trabecular bone ([Formula: see text]). The analysis stratified by tissue type versus the pooled analysis confirmed the validity of a common linear model for both types of tissue ([Formula: see text]). Despite its simplicity, the correlation obtained in this work does not depend on the acquisition settings of the micro-CT. TMD was shown to be dependent on the tissue investigated, with values in the range of 1.15–1.21[Formula: see text]mg/mm3 for trabecular bone, and 1.19–1.29[Formula: see text]mg/mm3 for cortical bone. Results are of some interest for generating micro finite elements models.

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