This last post on digital radiography is on detector sensitivity. This is probably the most talked about characteristic of digital radiography when the systems are being hyped. Detector sensitivity is the ability of the sensor/phosphor plate to respond to small amounts of radiation. There is no term used to measure this, instead the systems are merely described as using a decreased exposure time which will reduce radiation exposure to the patient. While several different numbers are often said about the decreased radiation exposure, the one thing hardly touched on is what film speed is this in comparison to. Some of the larger numbers, such as a 75% exposure reduction, are referring to moving from D speed film to a digital radiography (sensors) system. Digital radiography (sensors) use faster exposure times compared to computed radiography (phosphor plates).
Below is a table with approximate reduction in exposure times and radiation for both digital radiography and computed radiography systems. While this is an approximation, you may find you have or had smaller or larger changes in your exposure times to achieve your desired image.
|
Film speed |
Computed radiography (phosphor plates) |
Digital radiography (sensors) |
|
D |
~ 50% |
~ 75 % |
|
E |
~ 20 % |
~ 60% |
|
F |
~ 0 % |
~ 35% |
|
Computed radiography (phosphor plates) |
___ |
~ 50 % |
|
Digital radiography (sensors) |
~ + 50% |
___ |
I hope this information about detector sensitivity is helpful. If you have any questions or comments, please let me know.
Thanks and enjoy!