Shouldn't that be '...inversely proportional to SNR...' ?BobP said:...the NECR (noise-equivalent count rate), which is linearly proportional to SNR...
Not according to my lecturer...Tom.G said:Shouldn't that be '...inversely proportional to SNR...' ?
BobP said:However, the NECR (noise-equivalent count rate), which is linearly proportional to SNR, is higher in 3D PET scanners. These two facts seem to contradict each other and I am therefore slightly confused.
The NEC is the true count rate of a theoretical image without any scatter or random events which would give the same statistical quality image as a real image which includes scatter and randoms.Drakkith said:That sounds similar to Noise-Equivalent Temperature. Is NECR the number of signal counts needed to match the internal noise of the sensors?
Well my lecturer said that SNR is basically the same as NECR. So it have a lower SNR and a higher NECR :)Drakkith said:Okay. So it seems to me that the NECR for 3D PET is higher than that of 2D PET because the 3D PET real images are noisier and require more integration time to reach the same SNR as a 2D PET image.
In other words:
Real 2D PET
Signal: 100
Noise: 20
SNR: 5
Ideal 2D PET
Signal: 50
Noise: 10
SNR: 5
NECR: 50
Real 3D PET
Signal: 200
Noise: 40
SNR: 5
Ideal 3D PET
Signal: 100
Noise: 20
SNR: 5
NECR: 100I hope my terminology is okay, I'm used to talking about digital camera sensors and images, not PET sensors.
BobP said:Well my lecturer said that SNR is basically the same as NECR. So it have a lower SNR and a higher NECR :)
Ref post #3Tom.G said:Shouldn't that be '...inversely proportional to SNR...' ?
Ref post #7BobP said:Not according to my lecturer...
BobP said:Well my lecturer said that SNR is basically the same as NECR. So it have a lower SNR and a higher NECR :)
Sorry. When I say "basically the same" I mean a high SNR = high NECR...Tom.G said:Ref post #2
Posts #3 and #7 seem to conflict with each other. Please clarify.
A PET (Positron Emission Tomography) scanner is a medical imaging device used to produce detailed images of the body's metabolic and biochemical processes. It works by detecting the gamma rays produced by a radioactive substance injected into the body, which is absorbed by tissues and organs at different rates depending on their level of metabolic activity.
SNR (Signal-to-Noise Ratio) is a measure of the strength of the PET scanner's signal compared to the background noise. In PET imaging, a higher SNR indicates a more accurate and reliable image, as it reduces the impact of noise on the image quality.
NECR (Noise-Equivalent Count Rate) is a measure of the scanner's ability to acquire and process valid data while minimizing the impact of noise. It takes into account both the signal strength and the noise level, and is used to evaluate the scanner's performance in dynamic imaging studies.
As the SNR increases, the NECR decreases, and vice versa. This is because increasing the signal strength often leads to an increase in noise levels, and vice versa. Therefore, there is a trade-off between the two, and a balance must be struck to optimize the scanner's performance for different types of imaging studies.
There are several ways to improve SNR and NECR in PET scanners, including increasing the amount of radioactive substance injected, optimizing data acquisition and image reconstruction algorithms, and using advanced detector technology. Additionally, proper calibration and maintenance of the scanner can also help improve these performance measures.