I.I. vs. FPD Pros of FPDs Low weight and dimension ) Stability through device life Better image quality
Non ideal trajectory Irregular sampling step Off-line calibration required A calibration ring phantom with metal beads is used for calibration. Calibration should be performed for each used scan trajectory, since mechanical distortion is specific Calibration sets the correct correspondence between 2D projection and 3D position. It is repeated weekly.
Workstation Processing MIP (Maximum Intensity Projection) SSD (Surface Shaded Display)
Workstation Processing Surface vs. Volume Rendering Virtual Navigator
Workstation Processing Processing della workstation Coils and Clips Calibrated anatomycal measures Opposite to DSA (Digital Subtraction Angiography), which deletes still objects, this algorithm does reconstruct high contrast objects not moving and varying during the scan and enhances them over the vascular anatomy
Risultati Immagine DSA standard Aneurismi multipli dell’arteria carotide interna Viste ottenute con Volume Rendering (differenti proiezioni) Aneurismi multipli dell’arteria carotide interna
Dental FPD CT
Giuseppe Gentil, Francesco Maffesanti, Massimo Molinari, 2005/06 Multislice helical CT
scan start multi-row detector array trajectory of the rotating x-ray tube focal spot direction of continuous bed shift
multi-row detector array
z axis multi-row detector array
Reslicing
Maximum intensity projection
Rendering
Navigation
CRANIOPLASTICS Application in the field of maxillo-facial surgery -Precise cranial CT scan - Import into specific SW environment; e.g., Mimics (Materialize’s Interactive Medical Image Control System) - Segmentation of skull - Vectorization into a CAD environment - Design of prosthesis - Construction by 3D rapid prototiping GANTRY TILT = 0°
Segmentation by Thresholding
Segmentation by Region Growing and regular contouring by NURBS Polinomial contours by NonUniform Rational B-Splines (NURBS) 3D
Application: from 3D virtual model to real model by rapid prototyping
Application: design of prosthesis
Rapid prototyping by stereo-lithography
The polymer prototype is not directly used. Conversely, it is used as 3D model for fabrication or to create a mold (it stampo) were the final material is cast. Final material can be autologous or donor bone, hydroxyapatite, PMMA, Titanium silicon-rubber mold
La Cranioplastica I Materiali I materiali usati finora per la cranioplastica sono stati molteplici, ma molti di loro sono stati abbandonati per diversi motivi: scarsa biocompatibilità, ridotta maneggevolezza nel modellamento, alto costo… I materiali maggiormente utilizzati oggi sono: Osso autologoTitanio IdrossiapatitePMMA
La Cranioplastica Tecnica Chirurgica 1.Posizionamento paziente 2.Rimozione adesione pelle–dura madre
La Cranioplastica 3. Applicazione acqua ossigenata (disinfettare e coagulare)
Surgical implant of skull prosthesis
ECG gating for Cardiac CT
Small animal (rat) CT