Standardization of Radiographic Techniques PDF

Standardization of Radiographic Techniques DEFINITION OF “STANDARDIZATION” A framework of agreements to which all relevant parties in an industry or organization must adhere to ensure that all processes associated with the creation of a good or performance of a service are performed within set guide...

Standardization of Radiographic Techniques DEFINITION OF “STANDARDIZATION” A framework of agreements to which all relevant parties in an industry or organization must adhere to ensure that all processes associated with the creation of a good or performance of a service are performed within set guidelines. This is done to ensure the end product has consistent quality, and that any conclusions made are comparable with all other equivalent items in the same class. MODIFIERS OF STANDARDIZATION 1. Domain 2. Aim of Standardization 3. Type of radiographic technique 4. Type of radiographic image 5. Type of measurements DOMAIN Research or clinical Research needs higher level of standardization (accuracy) Clinical = evaluation, follow up (less accuracy) In clinical situations some issues could be omitted (in case of difficulty). AIM · Reproducible images · Accurate measurements Anatomic restrictions or radiographic technique restrictions could prevent obtaining very accurate measurements TECHNIQUE · Periapical · Panoramic · CBCT The way, level, and parameters of standardization differ according to used radiographic technique IMAGE · Conventional (Film + chemical processing) · Digitized images (film + chemical processing > Scanner or digital camera> Digital image) · Digital images (No chemical processing) MEASUREMENTS · Linear measurements (measure distance) · Angular measurements · Densitometric measurements (measure density) PARAMETERS OF STANDARDIZATION · Exposure · Projection (technique) · Processing · Viewing According to situation we start change in parameters IMAGE CHARACTERISTICS · Visual – (density / contrast) You need to adjust exposure, processing, and viewing in order to obtain accurate densitometric measurements · Geometric – Shape distortion (shortening / elongation) only one dimension – Size distortion (magnification) You need to adjust projection to avoid size and shape distortion in order to obtain accurate linear and angular measurements EXPOSURE PARAMETERS · kVp · mA · Exposure time (doesn’t exist in pnorama) In case of research —> 3 parameters should be standardized ** Exposure parameters affects density measurements but it doesn’t affect linear measurements In case of clinical follow up —> it doesn’t matter PROJECTION PARAMETERS · Paralleling technique · Film holder Panorama hard to be standardized No follow up with CBCT Periapical is used in follow up with paralleling technique (not bisecting) Film holder (with bite block) Rinn (XCP) (the lonely accepted film holder) Film holder only doesn’t guarantee standardization for research Patient should wear film holder with radiographic stent to make standardization RADIOGRAPHIC STENT · Direct – (rubber base) Radiopaque (mask alveolar crest) Slow dimensional changes Viscoelastic (deformed after a while and should be thick) – (wax) (rapid dimensional changes) Both not suitable for research · Indirect o acrylic resin More common with periapical o vacuum based More common with panorama Dimensionally stable- research FIDUCIAL MARKERS (RO MARKERS) · Metallic ball · Metallic cylinder · Orthodontic wire · Gutta percha The material differs according to radiographic technique. Used to calculate the magnification Used to determine(mark) the position of implants Metallic ball covered by wax to avoid artifact to calculate magnification Long span = wire with notches Panorama = cylinders or gutta percha Problem with CBCT = metal artifact (gutta percha can be used) Magnification = radigographic size of marker – actual size Panorama = magnification vertical and horizontal (more in anteriors) Horizontal measurement is not accurate in panorama Vertical measurement is more important for safety Anatomical morphology or inclination of objects render the measurements not accurate 100% (in 2D imaging) Accurate measurements in CBCT PROCESSING · Manual · Automatic Chemical processing used in clinical situations only Even automatic processor is not standardized enough for research Processing affects densitometric measurements Processing has limited impact on linear measurements Research = digital not manual or automatic or digitized VIEWING You should standardize degree of zooming, brightness and contrast Digitized images need calibration Densitometric measurements should be done on native scanner software Linear measurements are affected by degree of magnification DENSITOMETRIC MEASUREMENTS Certain softwares have tool for densitometric measurements e.g. (Digora, IDRISI) Density could measured in areas or lines AL STEPWEDGE A tool used if you want to measure density on digitized images Only used in lack of direct digital radiography CBCT Following items should be standardized in research using CBCT · FOV · Voxel size · Exposure parameters · Machine To standardize the position of slices used in measurements Super imposition by software can be used · Anatomical landmarks · Fiducial markers (in long span) More important in research cases CBCT not affected by processing or projection only viewing Barium sulfate markers can be used Completely edentulous = need denture + gutta percha Multiple missing teeth = waxing up + vacuum stent