Image receptors 2014.ppt

1. Image receptors Priyankesh 1 st year post graduate department of oral medicine and radiology

2. CONTENT INTRODUCTION HISTORY TYPES OF IMAGE RECEPTORS Radiographic film -direct action film -indirect action film Digital receptors Conclusion references

3. INTRODUCTION Image refers to picture or reflection of an object. Receptor means anything that respond to a stimulus . IMAGE RECEPTOR - a medium that changes X- ray beam into a visible image.

4. H istory EARLY 1900 – glass plates wrapped in black paper 1913 – hand wrapped cellulose nitrate films 1924 – cellulose triacetate films 1960 – polyester base 1980 – digital radiography ( research and development ) 1990 – CCD based imaging 2000 – only digital imaging

5. FIRST “FILM” GLASS PLATES CELLULOSE NITRATE HIGHLY FLAMMABLE EASILY TORN RESPONSIBLE FOR MANY FIRES IN HOSPITAL BASEMENTS CELLULOSE TRIACETATE

6. CLASSIFICATION OF X-RAY FILMS According to packaging 1. Single film packet 2. Double film packet According to coating of emulsion 1. Single coated 2. Double coated According to sensitivity 1. Direct action / non-screen film 2. Indirect action / screen film According to use 1. Intraoral films 2. Extra oral films 3. Duplicating films 4. Self developing film According to speed of film 1. Slow speed film 2. Fast speed film 3. Hyper speed G

7. DIRECT/ NON-SCREEN FILM

8. Wrapper – non absorbent paper or plastic or soft vinyl - two sides Tube side – pebbled or smooth surface, usually white Labeled side – usually two colors

9. INFORMATION ON LABELED SIDE: - name of manufacturer - number of films enclosed - raised identification dot - speed of the film - statement regarding placement of film

10. COMPOSITION OF X –RAY FILM

11. Base : transparent supporting material upon which emulsion is coated

12. Emulsion: Sensitive to X rays and visible light, records the radiographic image. Film emulsion can be on one side or both sides of base (single emulsion / double emulsion) Protective overcoat layered on top of emulsion Emulsion is a gelatin containing the film crystals Emulsion is the “active” layer of film Made of mixture of gelatin & silver halide crystals (fluorine, chlorine, bromine, & iodine)

13. Latent image

14. A type of film that is used to make an identical copy of an intraoral or extraoral radiograph . Used only in darkroom setting Not exposed to x ray Emulsion is present on one side of the film Emulsion side – dull Non-emulsion side – shiny Does not have orientation dot Emulsion side of film must be in contact with radiograph to be duplicated

15. CASSETTE

16. CHARGED COUPLE DEVICE Charge Coupled Devices (CCDs) were invented in October 19, 1969, by William S. Boyle and George

17. CCD

18. COMPLEMENTARY METAL OXIDE SEMICONDUCTORS Silicon-based semiconductors Electron hole pairs generated in pixels proportional to radiation dose Each pixel is isolated and directly connected to the transistor Transferred as a small voltage to transistor Transistors addressed separately, read by frame grabber Stored and displayed as a digital gray value

19. PHOTO STIMULABLE PHOSPHOR PLATES Photostimulable phosphor plates (PSP) absorb and store energy from x rays and then release this energy as light (phosphorescence) when stimulated by other light of an appropriate wavelength. photostimulable phosphor material used for radiographic imaging is "Europium-doped" barium fluorohalide . .

20. FLAT PANEL DETECTORS

21. REFERENCES Oral radiology- principle and interpretation, -White and pharoah , 5 th edition. Dental radiography, principles and techniques- Haring and jansen – 3 rd edition