Vernier Caliper Measurements Research Articles

Development of a phantom to evaluate the positioning accuracy of patient immobilization systems using thermoplastic mask and polyurethane cradle

The purpose of this study was to develop a new phantom to evaluate the positioning accuracy of patient immobilization systems. The phantom was made of papers formed into a human shape, paper clay, and filling rigid polyester. Acrylonitrile butadiene styrene (ABS) pipes were inserted at anterior-posterior (A-P) and right-left (R-L) directions in the phantom to give static load by pulling ropes through the pipes. First, the positioning precision of the phantom utilizing a target locating system (TLS) was evaluated by moving the phantom on a couch along inferior-superior (I-S), A-P, and R-L directions in a range from -5 mm to +5 mm. The phantom's positions detected with the TLS were compared with values measured by a vernier caliper. Second, the phantom movements in a tensile test were chosen from patient movements determined from 15 patients treated for intracranial lesions and immobilized with a thermoplastic mask and polyurethane cradle. The phantom movement was given by minimum or maximum values of patient movements in each direction. Finally, the relationship between phantom movements and the static load in the tensile test was characterized from measurements using the new phantom and the TLS. The differences in all positions between the vernier caliper measurement and the TLS detected values were within 0.2 mm with frequencies of 100%, 95%, and 90% in I-S, A-P, and R-L directions, respectively. The phantom movements according to patient movements in clinical application in I-S, A-P, and R-L directions were within 0.58 mm, 0.94 mm, and 0.93 mm from the mean value plus standard deviation, respectively. The regression lines between the phantom movements and static load were given by y = 0.359x, y = 0.241x, and y = 0.451x in I-S, A-P, and R-L directions, respectively, where x is the phantom movement (mm) and y is the static load (kgf). The relationship between the phantom movements and static load may represent the performance of inhibiting patient movements, so the accuracy of the immobilization system in the intracranial lesion will be estimated in advance by basic tensile test on the new phantom. The newly developed phantom was useful to evaluate the accuracy of immobilization systems for a Cyberknife system for intracranial lesions.

Assessment of Tophus Size

Dual-energy computed tomography (DECT) has recently been described as a sensitive method to detect urate deposits in patients with gout. The aim of this study was to compare the reproducibility of DECT with various physical measurement methods of tophus size assessment. Sixty-four tophi from 25 patients were analyzed. Each tophus was assessed by 2 independent observers using Vernier calipers and tape measure. All patients proceeded to DECT scanning of both feet. Urate volume within index tophi was assessed by 2 independent observers using automated DECT volume assessment software (n = 55 tophi). Five patients returned within 1 week for repeat physical assessment of tophus size. Dual-energy computed tomography scans from the returning patients were scored twice by both observers. Intraobserver and interobserver reproducibility was assessed by intraclass correlation coefficient (ICC) and limits-of-agreement analysis. Overall, DECT was more reproducible than the physical methods with interobserver ICCs for DECT of 0.95, for calipers 0.78, and for tape measurement 0.88, and intraobserver ICCs for DECT of 1.00, for calipers 0.75, and for tape measurement 0.91. Vernier caliper and tape measurements correlated highly with each other (rs = 0.84, P < 0.0001) but less well with DECT (for index tophi, r(s) = 0.46, P = 0.004 for both). Large variation was observed in the amount of urate deposits documented by DECT in tophi of similar physical size. Dual-energy computed tomography scanning is a highly reproducible method for measuring urate deposits within tophi. This imaging modality reveals the composition of tophi that contain variable urate deposits embedded within soft tissue.

ステレオ画像法に基づく三次元溶接変形計測法の開発

Due to the rapid improvement of digital cameras, especially the pixel resolution, digital image correlation (DIC) has been introduced to measure the deformation and strain of structures. Using digital cameras for the DIC technique is an easy and fast method for obtaining structural information, represented as all the pixel points in a photo. Because a wide range of structural deformation can be obtained with high accuracy, this method has the potential to be very useful.Currently, DIC can execute a measurement with high accuracy only when the out-of-plane displacement is small. When the out-of-plane displacement is large, the deformation causes the measurement error. Therefore, a stereo imaging method using two digital cameras is proposed in the present study. The proposed method can measure not only in-plane deformation but also out-of-plane deformation with high accuracy without calibration of the errors caused by the out-of-plane displacement.In this paper, the measurement accuracy of the proposed method for in-plane and out-of-plane deformation is discussed through the application of a bead-on-plate welding test. The proposed method can measure transverse shrinkage and angular distortion with high accuracy. In contrast to the vernier caliper and laser distance meter measurement methods, which can measure only a few points at a time, the proposed method using two digital cameras can measure the full field in a short time. These results confirm that the proposed method is more advantageous than other methods.

Sorafenib induces growth suppression in mouse models of gastrointestinal stromal tumor

Gastrointestinal stromal tumor (GIST) is the most common mesenchymal tumor of the gastrointestinal tract. Current therapeutic options include surgery and targeted molecular approaches such as imatinib and sunitinib. Our aim was to establish patient-derived GIST xenografts for the use of screening new drugs and improving current treatment regimens used in GIST. In this present study, we investigate the antitumor activity of sorafenib against patient-derived GIST xenografts. Murine xenograft models were given two oral doses of sorafenib daily for 30 days and growth of established tumor xenografts was monitored at least twice weekly by vernier caliper measurements. Western blotting was then used to determine changes in proteins in these xenografts before and after sorafenib therapy. Apoptotic and cell proliferation were analyzed by immunohistochemisty. Our data found that oral administration of sorafenib to mice, bearing patient-derived GIST xenografts, resulted in dose-dependent inhibition of tumor growth. Sorafenib-induced growth inhibition was associated with decreased cell proliferation, increased apoptosis, and reduction in tumor angiogenesis. Western blot analysis revealed that sorafenib inhibited C-Raf, phospho-extracellular signal-regulated kinase 1/2, and phospho-MEK1 (Thr286) slightly as well as phospho-c-Kit (Tyr568/Tyr570), phospho- platelet-derived growth factor receptor beta (Tyr1021), and phospho-Flk1 (Tyr951), suggesting that sorafenib inhibited GIST growth by blocking the Raf/MEK/extracellular signal-regulated kinase pathway and angiogenesis. Sorafenib also induced cell cycle arrest, evident through increased levels of p15 and p27 and decreased levels of p21, cyclin A, cyclin B1, and cdc-2. Our study provides a strong rationale for the clinical investigation of sorafenib in patients with GIST as well as an established platform for further drug evaluation studies using GIST xenograft models.

Determination of Cylindrical Soil Specimen Dimensions by Imaging with Application to Volume Change of Bentonite-Sand Mixtures

Abstract Volumetric shrinkage of compacted bentonite and sand mixtures has been continuously monitored at small strain levels (i.e., &amp;lt;5 %) using a digital image processing technique. A special digital measurement setup and a computer algorithm have been developed in order to identify volume of the drying specimens. Volume change of three compacted bentonite-sand mixtures at different initial moisture contents were recorded during drying by means of vernier caliper and digital measurements. Continuous monitoring of the volumetric shrinkage of specimens using digital images proved that digital measurement and data reduction methodology developed herein is capable of determining the shrinkage amount with desired accuracy. It is shown in the study that consistent volumetric shrinkage strain readings can be taken using this cost effective, nondestructive, and operator independent measurement setup, which may have become the preferred shrinkage measurement methodology in soil mechanics laboratory practice with some added features.

Non-Invasive imaging of small-animal tumors: high-frequency ultrasound vs. MicroPET.

Tumor volume measurement on small animals is important but currently invasive. We employ ultrasonic micro-imaging (UMI) in this study and demonstrate its feasibility. In addition, we use small animal positron emission tomography (microPET) as a preliminary effort to develop multi-modality small animal imaging techniques. The tumor growth curve from UMI is also compared to radioactivity from microPET. Both UMI and [18F] FDG microPET imaging were performed on C57BL/6J black mice bearing WF-3 ovary cancer cells at various stages from the second week till up to the eighth week. Segmentation and 3D reconstruction were also done. The growth curve was obtained in vivo noninvasively by UMI. The cell doubling time was 7.46 days according to UMI. This result was compared with vernier caliper measurement and radioactivity counting by microPET. In microPET, we obtained the time-activity curves from the tumor and the tumor-surrounding tissue. The tumor-to-normal-tissues ratios reached maximum at the fifth week after tumor cell implantation.

Ultrasonic Measurement of Bone and Bone Marrow Thicknesses in Femur Covered with Flesh by Inserting a Hip Prosthesis Stem

The thicknesses of the bone and the bone marrow region within a pig femur covered with flesh are investigated nondestructively by inserting a hip prosthesis stem via an ultrasonic pulse echo method. An ultrasonic wave is emitted toward the hip prosthesis stem via a normal probe attached to the flesh, and the distances from the normal probe to the boundary surfaces of the bone and the metal stem are measured by observing the time intervals between each echo. Subsequently, the exact thicknesses of flesh, bone and bone marrow region are measured using vernier calipers. The results of the ultrasonic wave and vernier caliper measurements are graphically presented and compared. The ultrasonic method is found to be applicable for the proposed purpose.