The Production Of Radiographic Image Flashcards
What are the 3 types of x-ray imaging?
Conventional radiography
Digital radiography
Computed radiography
Screens and phosphor crystals
X-ray excites crystal to emit light —> light exposes film —> more efficient and less radiation
Cassette
2 screens inside the cassette with film sandwiched between
Light produced from phosphor crystals embedded in each screen and light exposes the film from both screens
Fast screens
Large crystal size
Lower exposure (low mAs, short time)
Sacrifice detail (light is more diffuse)
Par speed (screen)
Average sized crystals
Average exposure and detail
Detail screens
Smallest crystal size
Highest exposure
Longer mAs
Greatest detail (light is less diffuse)
Characteristics of a good quality radiograph
Area of interest is on film
Proper positioning
Good contrast (fat helps)
Good detail
No film artifacts
High contrast
Short scale
Fewer shades of gray with greater difference between steps
Lower kVp
the image you want
Low contrast
Long scale
More shades of grey with less difference between steps
Higher kVp
good for thorax
Technical errors (causing poor image detail)
Low max: not enough rays
Motion: blurry (long exposure time)
Large patient size (scatter radiation)
Pathology in patient (causes of poor image detail)
Excess fluid in body cavity
Lack of normal fat to distinguish between abdominal structures
Overexposure
Image too dark
Caused by too high kVp or mAs
(Decease kVp first)
Underexposure
Image too light
Caused by too low kVp or too low mAs
Digital radiography
Digital ray sensors are used instead of traditional photographic film (replaced by detector device)
Processor, view boxes, data server and grids used
Advantages of DR
Time efficiency
Less radiation can be used to produce an image
Immediate image preview availability
Wider dynamic range
How does DR work?
Incident ray energy converted into light by a scintillator —> emoted light bundled by an optical lens to fit size of charge-coupled device detector —> converts light into electrical charges
Detector pads in DR
Charged-couple devices (CCDs)
Flat panel detectors (portable DR system)
Computed radiography
Similar to conventional, except in the place of a film to create the image, the imaging plate made of photostimulable phosphor
How is the imaging plate used?
How in a special cassette and placed under the body part or object to be examined, and the x-ray exposure is made
The IP is processed using a CR reader to generate a digital image and displayed on a computer monitor
How is CR used?
IP absorbs the energy from the rays, trapped in high energy electrons to create a stored image —> the image in the IP scanned in a CR reader using a laser beam and the traps electrons emit light photons —> light photons converted to additional signal by the photo multiplier tube —> then transferred to a computer for processing and display on a computer monitor
Digital imaging: commonalities
No radiographic film used
Signal from imaging plate for CR and sensor pad for DR sent to a computer for storage and display
Storage of data: picture, archiving, and communication system (PACS)
