Presentation on theme: "Processing the Latent Image Dr Mohamed El Safwany, MD."— Presentation transcript:
Processing the Latent Image Dr Mohamed El Safwany, MD.
Intended Learning Outcomes The student should be able to understand principles of radiological image processing at the end of this lecture.
Purpose of Conventional Film Processing Change silver halide crystals from film emulsion (after exposure to x-ray or light photons) to black metallic silver. Latent image (invisible until processed) is developed into a Manifest image. Improper or careless processing can cause poor diagnostic quality.
AUTOMATIC PROCESSING TRANSPORTATION SYSTEM DEVELOPER FIXER WASHER DRYER REPLENISHMENT SYSTEM
PROCSSING CHEMICALS Solutions are PRE- MIXED Outside Company usually provides service- Weekly or monthly Weekly or monthly Solutions should be replenished as necessary & changed regularly Solutions must be monitored (Daily QC strip).
Processor Chemistry Overview Developer – converts latent image into manifest image Fixer – clear the film of unexposed, undeveloped silver bromide crystals, promotes archival quality Wash – rid the film of residual chemicals
First Step Wetting the film to swell the emulsion
Developer Solution 3. Hardener: prevents damage to the film from over swelling of gelatin in automatic processors. -Gluteraldehyde 4. Preservative: Antioxidant that prevents oxidation of developer -Sodium Sulfite
Developer Solution 5. Restrainer: prevents chemical fog protects crystals from chemicals -Potassium Bromide 6. Solvent: dissolves & ionizes the developer chemicals -Water
Fixing Once development is complete, the film must be treated so that the image will not fade but will remain permanently. Fixing First step of fixing is the stop bath – to stop the developer chemicals
Wash Rid the film of residual chemicals Residual chemicals on the film will discolor radiograph over time. Cold water processors are less efficient in removing chemicals – Warm water processors much better. Agitation during wash process is essential
Wash & Dryer Systems Wash: Provide thorough removal of chemical solutions from the film. Dryer: Removes water from film by blowing warm, dry air
Transport System in Automatic Processors Conveys the film through different solutions (sections) by a series of rollers driven by gears, chains & sprockets. Done at a prescribed speed – determines length of time the film is in each solution
Transport System Components Feed Tray Rollers (Different Assemblies): 1. Entrance 2. Deep Racks 3. Turnaround 4. Crossover 5. Squeegee 6. Dryer Receiving Bin
Transport System (Rollers) Turnaround Entrance Deep Racks Crossover Squeegee Dryer Feed Tray
Engages a micro switch to start the replenishment system. Always feed the film evenly, using the side rails of the feed tray. Alternate sides from film to film. Short side of film against the side rail for proper replenishment.
Replenishment System Main function: Keep solution tanks full and assure proper solution concentration. As film is introduced into processor, sensor initiates solution replenishment Right & wrong way to feed in film -Feed in along short edge
Temperature Regulation Main function: To control the temperature of each section of the processor. Developer – most important solution to regulate Thermostatically controlled
Silver Recovery About ½ of the film’s silver remains in the emulsion after exposure & processing. Other ½ (unexposed silver) is removed from the film during fixing process. Silver is toxic to public water supply – must have proper disposal.
Safe Light 15 Watts Red filter Must be 3-6 feet from counter top or feed tray of processor Used to be amber or orange filter
Film Identification Pt name Exam date & time Pt x-ray number Pt Birthday/DOB Rt or Lt marker Optional –Exam type –Dr. Name
FILM ID PRINTER Name of patient place on top Cassette is “flashed” with name – can be done before or after image is taken Must be done BEFORE PROCESSING FILM
TABLE TOP FILM DUPLICATOR to MAKE COPIES OF FILMS
Digital Image Printing Dry processing – no chemistry No darkroom Less environmental impact Reduce costs
Dry Processing Uses a laser to form a latent image and heat to process the image Two types: Photothermography (PTG) Uses a laser to record the image signal (latent image) then film is heated to produce the manifest image Photothermography (PTG) Uses a laser to record the image signal (latent image) then film is heated to produce the manifest image Thermography (TG) Uses modulated heat source to produce the image directly Thermography (TG) Uses modulated heat source to produce the image directly
The Digital Receptor The digital receptor is the device that intercepts the x-ray beam after it has passed through the patients body and produces an image in digital form, that is, a matrix of pixels, each with a numerical value. This replaces the cassette containing intensifying screens and film that is used in non- digital, film-screen radiography. There are several different types of digital radiography receptors.
Image Processing One of the major advantages of digital radiography is the ability to process the images after they are recorded. Various forms of digital processing can be used to change the characteristics of the digital images. For digital radiographs the ability to change and optimize the contrast is of great value. It is also possible to use digital processing to enhance visibility of detail in some radiographs.
Digital Image Storage Digital radiographs, and other digital medical images, are stored as digital data. Advantages (compared to images recorded on film) include: Rapid storage and retrieval Rapid storage and retrieval Less physical storage space required Less physical storage space required Ability to copy and duplicate without loss of image quality Ability to copy and duplicate without loss of image quality
Communications Network Another advantage of digital images is the ability to transfer them from one location to another very rapidly. This can be: Within the imaging facility to the storage and display devices Within the imaging facility to the storage and display devices To other locations (Teleradiology) To other locations (Teleradiology) Anywhere in the world (by means of the internet) Anywhere in the world (by means of the internet) The total network available for transferring digital images is made up of a variety of integrated systems
The Advantages:- Minimal Space demand. Reduces radiation dose. Facility of post-processing. Simultaneous availability of image. Cost savings. Enhanced teaching and research opportunity.
Cost savings:- Elimination of films. Elimination of chemical and processors. Reduction in maintenance cost. Less requirement of staff. Reduction in space.
Assignment Two students will be selected for assignments.