INTRODUCTION
The daylight system is a method whereby x-ray films can be loaded into a cassette and, after being exposed, emptied from the cassette into an x-ray film processor in normal room lighting and without using a darkroom.
•An automatic system that accepts radiographic film, inserts it into the processor, and refills the cassette & to produce images without need of darkroom.
•A method of handling & processing of x ray film eliminating the time consuming, labour intensive, darkroom procedures.
•The development of roller type of x ray film processor in the late 1950’s was first step towards this goal.
DEVICE USED FOR PROCESSING
- Wet camera.
- Direct thermal print camera.
- Dry laser camera technology.
WET CAMERA
DRY VS WET CAMERA IMAGING
Disadvantages of automatic film processor :
1.Higher capital and maintenance costs.
2.Increased chemical fog due to higher processing temperatures.
3.Transport problems that can damage or destroy images during processing.
4.Image quality less than dry cameras.
5.Temperature regulation is very critical automatic processor.
DIRECT THERMAL PRINT CAMERA
•A thermal print head fitted with tiny heaters produces images. The heaters convert the supplied electrical energy into heat energy which forms images.
•The film is sensitive to heat only.
- Thermal Print Head,
- Image Scanning Line,
- Thermal Sensitive Media,
- Thermal Heat Element,
- Pressure Roller
FEATURE OF DIRECT THERMAL PRINT CAMERA
A direct thermal print camera has the following important parts –
i. film pickup area: handles up to five different film formats
ii. vacuum pump with valves: employed for lifting a film
iii. film transport: utilizes rollers, driven by a gearbox module
iv. thermal print head: operates at 52.5°C.
v. drum: maintains near contact with thermal head, while printing a film
vi. densitometer: performs a density check to confirm image quality and
vii. film receiving tray/sorter: for sorting film according to modality and patient records.
Printing in a direct thermal print camera
DRY LASER CAMERA TECHNOLOGY
- It is a two-step process involving a laser diode optic system and photothermography.
- The creation of a latent image using either optics or heat is followed by its conversion to a true image by photothermography.
- The latent image is initiated by a laser beam that releases photons into the sensitive layer during exposure, leading to the conversion of silver ions (Ag+) into metallic silver.
- The latent image on a film depends on the intensity of the laser beam, which is modulated in proportion to the intensity of the signal of the image data received.
- The film absorbs thermal energy for 15 s from a rotating drum whose temperature ranges from 120 to 140°C.
- In this way image is formed.
- The laser optical system.
- laser
- lens,
- laser modulator,
- polygonal mirror,
- toroidal lens,
- mirrors,
- film transport,
- rollers
Features of a Dry Laser Camera
•A dry laser camera has the following important parts:
- film supply drawers: handle many digital modalities using drawers, with different films sizes.
- film transport: rollers transport film sizes reliably
- film platen: a flat glass pane, which positions and secures a film for printing.
- optics module: a laser that writes a film on a platen.
- film processor: heat at around 124°C develops an exposed image.
- densitometer: controls image-quality parameters like contrast and density for consistency.
- film receiving tray/sorter: receives processed film after a check by a densitometer.
Printing in a dry laser camera
A typical print sequence in Carestream/Kodak laser camera contains A suction cup lifts a single film out of supply cartridge and feeds it into vertical transport rollers.
Film moves to a film platen (flat glass pane) which is the exposure area.
Platen holds the film while the scanner writes the image onto the film.
Film is transported over a processor drum, wherein the heat develops the film. •Film transport rollers move the exposed film through densitometer to a sorter and out to bins or alternatively placed at the top hood.
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