RAD 254 Digital Imaging

Basic Elements of Digital Imaging

CR/DR

CD/DR

• Image data CAPTURE

• Image data PROCESSING

• Image DISPLAY

• Image data ARCHIVING

• Image data DISTRIBUTION & TRANSMISSION

Electronic Imaging

• Produce image– Digitize (A-D Converter)

• Process Data– Output or D-A Conversion then Analog

Display» Network» Archive Image

Image Acquisition & Detection

• Image detector types:

– COMPUTED RADIOGRAPHY (CR)• Photostimulable Phosphor (PSP)

– DIRECT RADIOGRAPHY (DDR, “DR”)• Solid State X-ray Detector (SSXD)

CR/DR Differences (steps)

• COMPUTED RADIOGRAPHY(CR)– X-ray – PSP – A-D Conversion – Data

• DIRECT RADIOGRAPHY (DDR, “DR”)– X-ray – SSXD - Data

Image Data Processing

• The selection of processing algorithms, and anatomic regions and radiographic projections controls how the acquired (latent) image is presented for display

Image Display

• In both CR and DR, a separate device MUST be used to display (as well as view) the digitized image (video monitor)

– High resolution (1.5-2.5k matrix)– Diagnostic– Clinical Review– Web based

Image Data Archiving

• Storage and retrieval

• RAID– Storage – Terabyte (Tb) capacity

• Digital Linear Tape (DLT)

• Application Software Provider (ASP)

Image Data Distribution/Transmission

• One of the greatest strengths of a digital imaging system is the ability to share images simultaneously with multiple sites, sometimes over great distances (Iraq)– PACS– Teleradiology

Myth

• “DR” will turn a bad tech into a good tech!

• TRUTH – Digital radiography makes people “stupid” = give them an “auto pilot” mentality

Myth

• “Positioning and collimation don’t matter”

• Truth: Positioning and collimation are MORE critical with digital imaging systems

Myth

• “X-ray techniques don’t matter – you can use whatever you want.”

• Truth: Images almost always look better at higher exposures – very possible to over-expose the patient!

Caveat:

• Typically use HIGHER kVp– Get the photons to the image receptor

– Algorithm to determine image quality

• STILL GREAT POTENTIAL TO OVER IRRADIATE THE PATIENT

Myth

• “DR only operates as a 200 speed system.”

• TRUTH: Can operate at whatever speed system you desire… but remember– NOISE vs. X-RAY DOSE

Myth

• “You can’t use grids with a CR system.”

• TRUTH: Grid use is still an important part of obtaining good image quality and controlling scatter

Computer Technophobia Nagy, P

• “A Symantic study found that 70% of users experienced difficulties with computers. Symptoms included swearing at computers, loss of productivity, and emotional distress. 21% of users suffer from ‘PC RAGE,’ sometimes involving physical assault on and damage of a computer.”

Skill sets NOT to forget:

• Basic Radiography 101– Proper patient positioning– Proper beam restriction– Proper exposure factors– Correct patient ID– Correct R and L marker use

Skill sets NOT to forget:

• Basic x-ray physics– How a radiographic image is made– GOOD image quality elements– Effects of incorrect x-ray exposure selection

and image quality

New Skill Set Development:

• Critical thinking skills

• Ability to identify a good image

• Knowledge of how to fix a repairable bad image

• Understanding the exposure indicator

New Terminology

• PACS– Picture Archival and Communications

Systems

• PPACS– Picture and Paper and Communications

System

New Terminology

• Teleradiology

• ASP– Application Service Providers

• DICOM– Digital Images and COmmunication in

Medicine

• HL-7– Health Level - 7

New Terminology

• HIS– Hospital Information System

• RIS– Radiology Information System

• HIS/RIS Broker (make sure they talk to each other)

Electronic Medical Record (EMR)

• DICOM Standard

» Work Stations

» HL-7 Standard

21st Century Imaging

• All modalities will be in digital format

• Direct to Digital acquisition (SSXD)

• On-line access to patient records

• “Total” patient record (EMR)

• Software and equipment changes

• Radiation exposure a MAJOR concern

• Remote reading stations miles away

STOP the BS and just tell me!

• In CR – the photostimulable phosphor (just like an intensifying screen) is exposed to x-rays. The PSP cassette is then “scanned” by a laser “reader” to obtain the image (stored images are released as varied shades of “light”)

• DR/DD uses a “flat panel detector(s) and a scintillator combined with a photodiode the light produced is “digitized” and translated into “densities” for computer viewing.

Thanks to:

• Rolando R. Reyes, B.S., R.T.(R)– Senior Project Manager– Eastman Kodak Health Imaging– Rochester, NY