The Field of Digital Radiography Loren Sachs Instructor What is Digital Radiography?  Historically, digital radiography referred to specialized modalities that produced digital images  Examples would include: – – – – CT MRI Nuclear Medicine Ultrasound Digital Radiography Today  Since the early 1990s, Digital Radiography has grown to include Computed Radiography(CR) and ‘true’ Digital Radiography(DR) or Direct Radiography  Our lecture today will focus on CR and DR Digital Terms  Pixel – Picture element This is the basic component of the digital image, it is what we see dimensional  Voxel – Volume element This is a dimensional element that includes depth The pixel is essentially the end of the voxel  Matrix – The actual image we see is made up of a series of pixels in rows and columns called a matrix Generally, the larger the matrix the better the spatial resolution of the image  Bit – The amount of gray scale in the image The bit is the exponent to two, ie, a bit image is two to the second or four So the image would have shades of gray possible Today, most images are 10 or 12 bit  FoV – Field of view This is how much anatomy is displayed A 12 cm FoV will display 12 cm of anatomy on the screen The smaller the FoV the more magnified the anatomy is  Window width – The gray scale of the digital image The larger the width the more grays demonstrated the lower the contrast of the image  Window level – The density or brightness of the image The higher the number the brighter the image Computed Radiography  The technical aspects of CR are similar to what you see in the traditional analog radiology department, i.e., the technologist exposes a cassette that is then processed  CR differs from analog in that the CR cassette contains a phosphor plate instead of a sheet of film CR Overview The Technology of CR  After the cassette is exposed by the x-ray beam, the cassette is loaded into a reader  The reader removes the phosphor plate and exposes it to a laser, stimulating the phosphors  The light emitted from the plate is collected, quantified, and digitized CR Processing Advantages of CR  The major advantage of CR is that existing radiology rooms can use the technology – Consequently, the Radiology department can be digital at a relatively low cost, between $100,000-150,000 per reader  Also, due to the similarities with traditional radiography the learning curve is much shorter with CR Digital Radiography  DR uses no cassette The image capture device is embedded within the table-top  The advantage here is that the steps involved in processing a ‘cassette’ are eliminated resulting in a huge increase in productivity  Studies have estimated a 100% increase in room throughput DR Overview Technology of Digital Radiography  There are two types currently being used – Direct – Indirect Direct Digital Radiography The photoconductor is made up of amorphous selenium Indirect Digital Radiography The intensifying screen is made up of cesium-iodide crystals and the photodetector is made up of amorphous silicon Which DR Methodology is Best?  It depends entirely on who you listen to  Basically, different manufacturers are using proprietary technology and claiming theirs is the best  Ultimately, it will be decided by end-users DR Issues  The significant disadvantage for DR is cost  Normally, rooms with DR technology have to be constructed from the ground up Today, the average DR room cost is $400,000-600,000 plus construction costs  Construction costs can be overwhelming, particularly in older buildings that need to be brought up to code How does CR and DR Affect You the Technologist?  RSV is less for both CR and DR when compared to film/screen combinations Consequently, techniques are going to be higher  Centering and collimation are REQUIRED  You gain a tremendous amount of exposure latitude  Post-processing manipulation allows you to adjust film quality How does CR and DR Affect You the Technologist?  By selecting processing algorithms you can obtain different anatomical information with one exposure – A PA chest film and be reprocessed as a PA rib film  These methodologies are not a panacea for being a ‘bad’ technologist How does CR and DR Affect the Patient and Medical Care?  Patient dose goes up with these systems for an individual exam; however, there are fewer repeats  Films are available hospital-wide almost immediately and can be view in multiple locations simultaneously  No films get lost  Everyone associated with a patient’s films becomes more efficient Other Considerations  In order to gain maximum efficiency with CR and DR a RIS/PACs systems needs to be deployed  RIS, Radiology Information Systems, are used to manage non-image patient data, i.e exam number, dictation status, and billing  PACs, Picture Archiving Computer, allows for the distribution of images over a pre-described area Conclusion  Digital radiography will change the way technologists practice radiography  However, it will not eliminate the need for a quality education and an understanding of radiology principles In fact, digital radiography will require additional learning in order to maximize its usefulness  ... Digital Radiography Today  Since the early 1990s, Digital Radiography has grown to include Computed Radiography( CR) and ‘true’ Digital Radiography( DR) or Direct Radiography  Our lecture today... Technology of Digital Radiography  There are two types currently being used – Direct – Indirect Direct Digital Radiography The photoconductor is made up of amorphous selenium Indirect Digital Radiography. .. Digital Radiography?  Historically, digital radiography referred to specialized modalities that produced digital images  Examples would include: – – – – CT MRI Nuclear Medicine Ultrasound Digital