Extraoral Radiography口外照相技術(shù)ppt課件

1、 Extraoral Radiography Used for Panoramic, Lateral Jaw, Cephalometric, Skull and TMJ views X-ray MachineIntraoral may be used for extraoral films but not recommendedPan/Ceph standard for ortho, oral surgeryExtraoral/Specialty rotating anode; because of high mA, long exposure Intraoral Pan/CephSpecia

2、lty ExtraoralHead Positioner/Film Holdercassette holderhead positionerCassette/Film Extraoral Film T-Mat (G, L, H) Ektavision5” x 12”, 6” x 12”, 8” x 10”gridprimary x-raysscatter radiationfilmGridintraoralcentral ray enters 2” above, ” behind EAMTranscranial TMJIdentify changes in TMJ regionfloorMSP

3、red arrow = head of condyleblack arrow = glenoid fossaLateral Cephalometric Identify trauma, abnormalitiesAssess facial growth; treatment recordfilm at set distance from MSPfilm horizontalextraoral x-ray unitMSPfloorMSPSimpson, Homer 12/2/02Posteroanterior (PA) SkullIdentify trauma, pathology, ordev

4、elopmental abnormalitiesFPfloorMSPextraoral x-ray unitTaken with intraoral x-ray machine. (Note round collimation). Not recommended, but possible.WatersEvaluate the maxillary sinusMSPfloorextraoral x-ray unit(Sinus view)tip of nose 1” from cassetteCRFPSubmentovertex Identify location of condylesImag

5、e zygomatic arch fracturefloorMSPextraoral x-ray unitfloorFPcentral rayReduce exposure to 1/3 SV settingZygomatic Arch ViewReverse TownesImage fractures of the condylar neckhead tipped down mouth openextraoral x-ray unitfloorMSPCRFPCaldwellIdentify trauma, especially to area of orbitextraoral x-ray

6、unitfloor(Orbit view)tip of nose and chineven with cassetteMSPCRFPTomography (Laminography) Used to image TMJ X-ray procedure Images layer or slice Objects outside slice are blurredLinear TomographyCorrected TomographyLinear ArticulareminenceCondyleGlenoidFossaLinearMulti-directionalTranscranial Pan

7、oramic Film(special computer positioning)Computed TomographyX-ray procedure2. Section or slice imaged 360-degree rotation of x-rays/ detectors Radiation /detector/computer/ image(CT)Computed Tomographyx-ray source360 rotationdetectorsComputed TomographyFan beamx-ray tubecollimatordetectorsAble to im

8、age soft tissue without contrast agentsMagnetic Resonance Magnetic field aligns atoms (Hydrogen) Radiowaves alter alignment Atoms realign, releasing energy Computer produces imageNO IONIZING RADIATIONMagnetic Resonanceradiofrequency coils Magnetsliding table ArthrographyRadiopaque contrast agent inj

9、ected into joint2. Articular disk outlined3. X-ray procedure (fluoroscopy, tomography)TMJ Imaging MRI No Yes Arthrography Yes Yes CT Yes Yes Tomography Yes No Transcranial Yes No Panoramic Yes NoX-ray Disk Sialography X-ray procedure2. Radiopaque contrast agent3. Images salivary glands and ducts Sci

10、ntigraphy (Radionuclide Scan)Radioactive pharmaceutical agent2. Tissue specificity3. Gamma rays emitted4. Gamma camera image UltrasoundHigh-frequency ultrasonic vibrations2. Echoes at tissue density differences3. Varying echo intensities image NO IONIZING RADIATIONUltrasound echoesCone Beam CT Cone-

11、shaped x-ray beam 360-degree rotation around head Scan time around 20 seconds 2D or 3D images Patient exposure = AFM $170K-300K; $30K yearly upkeepCone Beam CTflat-panel detectortubeheadX-ray machine Sensor Computer Monitor Printer Digital Radiography X-ray Machine Low kVp (70), mA (5) Accurate time

12、r Small focal spot DC circuit Underexposure GraininessSensors CCD: Charged Coupled Device CMOS: Complimentary Metal Oxide Semiconductor Real Time Imaging (Direct) Wired (most common) or wirelessImage ReceptorsPros “Instant” image Better resolution More durable Cons Rigid and thick (3 to 8 mm) Expens

13、ive ($5,000 to $14,000) Most have wire connecting sensor to computer CCD, CMOSPlates PSP: Photo-stimulable Phosphor Laser scan (Indirect) Requires reduced lighting when scanning sensor plates Images erased by exposure to light before reusing plateImage ReceptorsSensorPlastic sleevePSPPSP: Photostimu

14、lable PhosphorPros Patient friendly; no change in technique More film sizes to choose from Plates relatively inexpensive ($35+) Wider exposure latitudeCons Easily damaged More time consuming (laser scan) Less resolutionUse paralleling, bisecting angle or bitewing technique. Biteblocks are different

15、for the direct sensors, but rest of instrument is the same.Biteblocks for CCD, CMOSRegular Rinn instruments for PSPBoth Direct and Indirect digital systems have panoramic and cephalometric applications. The direct is much more expensive.Computer2+ GHz Pentium 4 with 256 MB RAMLarge storage capacity

16、hard drive Periapical = 300-400 KB Pan/ceph = 4-7 MBCD/DVD writerLaptop optional MonitorCRT for radiographic interpretationLCD flat panel for patient presentation Best for color, such as photos Contrast ratio of 400:1 Dpi less than 0.27 mmPrinterDiagnosis made on monitorGood quality ink jet or dye s

17、ublimationPhoto quality paperDigital Radiography Advantages Reduced patient exposure (60-90%) Ability to enhance image Improved patient education “Instant” image (CCD, CMOS) Better workflow (CCD, CMOS) Digital Radiography Advantages Environmentally friendly (no lead, silver) No darkroom errors Impro

18、ved archival quality of images Easier transfer of information(continued) Cost comparisonNew practice: digital cheaperOngoing costs: digital cheaperCCD/CMOS system cheaper than PSP when buying only one sensorCheck warranty costsPractice Management SoftwareMost systems compatible but check to make sur

19、e DICOM compliant digital software; better digital image management and sharing of informationApplication Service ProviderStore images on Internet siteSmall monthly service fee“Chat” rooms (password protected) ScannersArchive current filmsManipulate digital image of films to “recover” informationSend information to i