Correlation between two-dimensional micro-CT and histomorphometry for assessment of the implant osseointegration in rabbit tibia model

Background Histology is considered as a gold standard for analyzing bone architecture. However, histomorphometry is a destructive method and only offers the bone information of a limited location. Micro-computed tomography (μCT) is a non-destructive technology and provides a slice at any site. The aim of this study was to compare the correlation of the Bone-to-Implant Contact ratio (BIC) between 2D micro-CT (μCT) and histomorphometry and to investigate a method for assessing the osseointegration of the implant by 2D μCT. Methods A total of 18 implants were divided into three groups (6 implants per group), and inserted into the rabbit tibia defects as follow: implant only (Implant group), implant with β-TCP/hydrogel (TCP group), implant with rhBMP-2 loaded β-TCP/hydrogel composite (BMP-2 group). After 4 weeks of implantation, the specimens were collected to take the micro-CT scan with an aluminum filter and performed H&E staining on the undecalcified sections. The 2D μCT slices were chosen at an angle of 0°, 45°, 90° and 135° with the representative histological section to measure BIC. And the correlations between BICs of 2D μCT and BICs of histology were evaluated. Results In each group, BICs at the same sites measured by histomorphometry and corresponding 2D μCT presented the same trend and shown no significant difference between the two methods (P > 0.05). BICs of histological sections and BICs of corresponding 2D μCT slices presented a strong correlation in the implant group (γ = 0.74, P = 0.09), a moderate correlation in the TCP group (γ = 0.46, P = 0.35), a weak correlation in the BMP-2 group (γ = 0.30, P = 0.56). In the implant group, the relationship between BIC-Mean-μCTs and BICs-Histology has presented a significant linear correlation (γ = 0.84, P = 0.04). Conclusions Integrating bone information of several 2D μCT slices in different sites to measure BIC is a feasible method for assessing the implant osseointegration.

Kilovolt Peak Meter Design as a Calibrator of X-Ray Machine

This research aimed to design the KvP meter for checking the error of output voltage from X-Ray machine with the range of 50-70 KvP. It used Arduino Gelatino microcontroller programmed with Arduino IDE software as data processor of detector result. The detector was designed based on the physics principle using material attenuation coefficient namely aluminum whose good effect in reducing the energy level of X-ray photons. Thus, the photodiode sensor only read the effective energy of the X-ray energy. Based on the radiation intensity ratio through the aluminum filter with 0.25 mm and 0.5 mm thickness, it is better to measure X-ray tube voltage non-invasively The KvP Meter was tested by setting duration of X-ray exposure that was 0.3 second, tube current was 10 mA, and KvP Meter distance from collimator was 90 cm. A prototype unit was made, and the performance was tested in terms of error and precision. After testing and analyzing the data, the error result was less than 5.1% with the highest measurement precision of ± 1.50. It is generally concluded that this equipment can be used to measure the voltage of the X-ray tube.

Towards intraoperative microCT imaging of breast cancer resections.

147 Background: MicroCT analysis of breast cancer resections was shown by Rong et al. [Tang R et al. (2013) The Breast Journal 19(5), 485-489; Tang R et al. (2013) Breast Cancer Research and Treatment 139(2), 311-316] to attain equivalence with pathology-histology in the assessment of positive margin. However, Rong et al. noted that the 14 minute scan cycle time–7 minutes scan, 7 minutes reconstruction–was a potential limitation. Methods: This paper reports the development of microCT instrumentation and software to address this and other technical challenges. These include (a) reducing the scan-reconstruction time, (b) a small desktop footprint, (c) reconciling optimal soft tissue contrast with minimizing artefacts from inserted metal wires and large calcifications, and (d) features to aid hospital workflow such as a barcode reader, an optical camera to photograph the specimen, and process automation. Scans were done with the purpose-built SkyScan1275 table-top microCT scanner, on frozen anonymous archived breast cancer resection samples. Results: Minimum scan time retaining acceptable image quality was 3 minutes. Reconstruction time was reduced to less than a minute by PC graphics accelerators. Scan-reconstruction cycle time can thus be < 4 minutes. A small (105 x 64 cm) desktop footprint with a weight of 160 kg, requiring only a sturdy laboratory desk, has also been attained in this scanner. Artefacts from large calcifications and metal wires were reduced to non-obtrusive levels by scanning with 1mm aluminum filter and software techniques. An automated scan sequence was developed with sample holders recognized electronically in the scanner. On pressing a single button, the scanner automatically goes to the appropriate magnification and sample height, scans the sample, then reconstructs the scan with preset parameters, and finally opens the reconstructed dataset in software for interactive volume-rendered viewing. Sample barcode reading and optical photo taking can be included in this auto-scan sequence. Conclusions: These developments bring microCT nearer to realizing its potential as an intraoperative “back-table” technique in breast cancer surgery to obviate revisions and improve the surgery process and outcome.

Experimental evaluation of protons emission from a plasma focus device

Solid state nuclear track detectors have been used for measuring axially emitted protons from a 2.2-kJ energy plasma focus device. The flux of the protons emerging out from the pinched plasma column of the plasma focus device has been found to saturate the CR-39 detectors. Aluminum filters have been used to avoid the saturation effect. By varying the aluminum filter thickness as well as the etching time of CR-39 detectors, proton tracks have been analyzed. Proton energy above 200 keV to about 1 MeV has been measured by using different thicknesses of aluminum filters. On increasing the etching hours, the most probable track diameter is found to be shifted from lower to higher values. The track number density decreases on increase of the filter thickness, whereas the track diameters increase linearly with respect to the etching time.

Preliminary Results on Irradiance Measurements from Lyra and Swap

The first and preliminary results of the photometry of Large Yield Radiometer (LYRA) and Sun Watcher using Active Pixel system detector and Image Processing (SWAP) onboard PROBA2 are presented in this paper. To study the day-to-day variations of LYRA irradiance, we have compared the LYRA irradiance values (observed Sun as a star) measured in Aluminum filter channel (171 Å–500 Å) with spatially resolved full-disk integrated intensity values measured with SWAP (174 Å) and Ca II K 1 Å index values (ground-based observations from NSO/Sac Peak) for the period from 01 April 2010 to 15 Mar 2011. We found that there is a good correlation between these parameters. This indicates that the spatial resolution of SWAP complements the high temporal resolution of LYRA. Hence SWAP can be considered as an additional radiometric channel. Also the K emission index is the integrated intensity (or flux) over a 1 Å band centered on the K line and is proportional to the total emission from the chromosphere; this comparison clearly explains that the LYRA irradiance variations are due to the various magnetic features, which are contributing significantly. In addition to this we have made an attempt to segregate coronal features from full-disk SWAP images. This will help to understand and determine the actual contribution of the individual coronal feature to LYRA irradiance variations.