1. When the dose is low, photon and other sources of noise will be a problem. How do you propose to overcome this problem with CAD?
2. Nowadays, DIRECT and INDIRECT detectors are used in digital radiographic X-Ray units and these are commercially available. They provide low dose because of better quantum efficiency using improved detectors (either selenium or pn junction detectors coupled to rare earth scintillators) and are therefore preferred for screening or radiography. Why should one use a bulky CT unit for low dose screening?
3. For better nodule detectability, the system should have a better resolution. Will CT provide this?
From: Dr Sankaran Ananthanarayanan with best wishes
Sankaran Ananthanarayanan,
1- Several filtering algorithms (mostly nonlocal) were proposed to overcome the degradation of image quality caused by noise due to photon starvation:
Article An adaptive nonlocal filtering for low-dose CT in both image...
https://posterng.netkey.at/esr/viewing/index.php?module=viewing_poster&task=viewsection&pi=117919&ti=385652&si=1161&searchkey=#poster
Article Effects of Iterative Reconstruction Algorithms on Computer-a...
https://www.academicradiology.org/article/S1076-6332(16)30337-3/fulltext
https://www.sciencedirect.com/science/article/abs/pii/S0720048X14005385
https://www.osapublishing.org/DirectPDFAccess/37DF41D1-B457-CD19-A265EAC83557729D_240070/oe-20-16-17987.pdf?da=1&id=240070&seq=0&mobile=no
Article A sinogram denoising algorithm for low-dose computed tomography
2- Because Ultra-low-dose CT (ULDCT) and Low-dose CT (LDCT) (Microdose CT) provide better diagnostic screening performance than digital radiography, especially in early lesion detection:
Article To Screen or not to Screen: Low Dose Computed Tomography in ...
Article Lung cancer screening: Computed tomography or chest radiographs?
3- While several studies have shown that diagnostic performance may be impacted when using LDCT (Microdose CT), especially in the detection of smaller lung nodules, the general screening performance is only slightly impacted, and can easily be corrected using CAD and smoother reconstruction filters:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4654704/
Article Investigation of lung nodule detectability in low-dose 320-s...
https://www.ajronline.org/doi/10.2214/AJR.14.12921
Article Radiation dose of digital radiography (DR) versus micro-dose...
Hope that helps!
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