9-4 Ying Zhu
Transcription
9-4 Ying Zhu
Fabrication of a Small Animal Restraint for Synchrotron Biomedical Imaging Using a Rapid Prototyper Y. Zhu, H. Zhang, R. McCrea, B. Bewer, S. Wiebe, H. Nichol, C. Ryan, T. Wysokinski, and D. Chapman Biomedical Engineering University of Saskatchewan Synchrotron S h t R Radiation di ti I Instrumentation t t ti 2007 Baton Rouge, LA, April 27, 2007 1/14 Motivations Motion artifacts are of p primary y concern in biomedical imaging. g g The study may require extended periods of time The study may require positioning accuracy. g movements. Animals under anesthesia continue to make breathing Motion may blur the image and reduce image quality. Excessive restraint increases morbidity and mortality. A well designed physical restraint is of great importance 2/14 Head restraints Types of head restraints found in literatures: Rigid mounting of the bone or skull through the skin A.M. Wyrwicz, et al., Mag. Reso. in Med. 44 (3) (2000) 474. B Box or cylinder l d restraints with h ear pins and d sometimes a bite bar. M.W. Bidez, et al., J. Biomech. 27 (10) (1994) 1271. 3/14 Head restraints Types of head restraints found in literatures: Rigid mounting of the bone or skull through the skin B Box or cylinder l d restraints with h ear pins and d sometimes a bite bar Plaster or resin molds taken directly from the animal K.D. Faulkner, Aust. Dent. J. 20 (1) (1975) 19. 3/14 Head restraints Types of head restraints found in literatures: Rigid mounting of the bone or skull through the skin B Box or cylinder l d restraints with h ear pins and d sometimes a bite bar Plaster Pl or resin molds ld taken k directly d l from f the h animall B. Sanghera, et al., J. of Med. Eng. and Tech. 26 (1) (2002) 16. M.N. Pilipuf, et al., J. Neurosurg. 82 (6) (1995) 1082. Rapid p prototyping p yp g technology gy used for f human head restraints 3/14 Head restraints Types of head restraints found in literatures: Rigid mounting of the bone or skull through the skin B Box or cylinder l d restraints with h ear pins and d sometimes a bite bar Plaster l or resin molds ld taken k directly d l from f the h animall Rapid p prototyping p yp g technology gy used for f human head restraints An animal restraint f fabricated using g a rapid p prototyper p yp ? 3/14 Fabrication Procedures Fabrication of an animal restraint using a rapid prototyper: (Digital Imaging and Communications in Medicine) Medical CT - DICOM Image editing - DICOM Software conversion - STL F b i ti Fabrication - a reall 3D restraint t i t (Standard Tessellation Language ) Experiments 4/14 Fabrication Procedures - Medical CT Medical CT (0.625mm/slice, 0.47mm or 0.35mm transverse) CT image storage of DICOM format DICOM image i data d t of f the th rats t The first rat (420g) The second rat (486g ) 5/14 Fabrication Procedures - Image editing IDL (Interactive Data Language) DICOM Toolkit Select a common region of interest for all slices. Define D fin animal nim l outline utlin usin using an n appropriate pp p i t grayscale s l th threshold sh ld. Expand the animal outline using a convolution function by 3mm Combine the outlines to make a shell of the restraint Rotate and orient Enlarge the nose and ear holes Attach support frame and labels to the restraint 6/14 Fabrication Procedures - Image editing DICOM images of rat head restraints The first rat head restraint The second rat head restraint The Novel Field Flatteners Specifically Fabricated for Small Animals by a Rapid Prototyper for K-Edge Subtraction Imaging, Y. Zhu, et al. 7/14 Fabrication Procedures - Conversion and fabrication JuliusLight from Julius Software Framework - Accurate or smooth surface modeling Eden500VTM from Objet Geometries Inc. - Vero V White, Whit Transparent T t STL files of the restraints The first rat The second rat The second restraint on Eden500VTM 8/14 Fabrication Procedures - Fabrication The first rat head restraint: Smooth surface modeling, Vero White The second rat head restraint: Accurate surface modeling, Transparent 9/14 Fabrication Procedures - Experiments K-edge subtraction imaging experiments at the CLS HXMA beamline 0.25mm 0 25mm*28mm 28mm beam beam, 100eV above or below the iodine K edge line scan mode at 2mm/s vertical scan velocity 10/14 Results - A live rat in lateral view A B C 1 min i llater t 4 min i llater t D images above iodine K edge K-edge E: (B – A)/A 5 min i llater t F: (C – A)/A G: (D – A)/A normalized subtracted images 1 min later 2.7% 4 min later 2.7% 5 min later 2.8% Results - A live rat in dorsal-ventral view A B C 1 min later 4 min later D images below iodine K edge K-edge E: (B – A)/A 5 min later F: (C – A)/A G: (D – A)/A normalized subtracted images 1 min later 2.9% 4 min later 3.0% 5 min later 3.1% 12/14 Conclusions Conclusions: Rapid prototyping is a simple, fast and relatively inexpensive method to fabricate a humane, customized animal restraint The restraint holds great promise in improving the quality and repeatability of images while reducing stress on experimental animals Drawback: Limited tolerance to animals of different sizes Smooth surface molding Averaging slightly displaced DICOM images 13/14 Acknowledgements V. Verge, g B. Juurlink, N. Cox, University y of Saskatchewan T. Anderson, L. Toews, Royal University Hospital R. Wilson and H. Berg, Engineering Machine Shop HXMA beamline, Canadian Light Source SHRF Research Group Facilitation Grant 14/14