Content deleted Content added
first draft |
additions to application section |
||
Line 1:
{{AfC submission|t||ts=20201206074951|u=Erik.Fredenberg|ns=118|demo=}}<!-- Important, do not remove this line before article has been created. -->
Photon-counting mammography was introduced commercially in 2003 and was the first widely available application of photon-counting detector technology in medical x-ray imaging. Photon-counting detectors are fast enough to register single photon events and can reduce patient dose and enable quantitative imaging.
== Basic principle ==
Line 7:
Fig. 3 shows the basic principle of a photon-counting spectral detector according to the description above.
Stryk ev detta stycke eller förkorta och lägg in informationen i nästa stycke. Fokusera på applications.
== Clinical applications and advantages ==
Dose reduction▼
Rejection of electronic noise
Energy weighting
Spectral imaging▼
Scatter rejection
▲Dose reduction
The combination of equally (or optimally) weighted photons, rejection of electronic noise, and efficient scatter rejection together lead to the possibility of reducing dose while keeping image quality on par with conventional technologies. A study that compared photon-counting mammography to the state-wide average of the North Rhine–Westphalian mammography screening program in Germany reported a slightly improved diagnostic performance at a dose that was 40% of conventional technologies Fortsätt här!
Diagnostic performance was assessed with cancer detection rate, recall rate, and proportion of small invasive cancers and ductal carcinoma in situ (DCIS).
Digital Mammography Screening with Photon-counting Technique: Can a High Diagnostic Performance Be Realized at Low Mean Glandular Dose?
Stefanie Weigel, Shoma Berkemeyer, Ralf Girnus, Alexander Sommer, Horst Lenzen, and Walter Heindel
Radiology 2014 271:2, 345-355
▲Spectral imaging
tomosynthesis
Line 27 ⟶ 46:
Another challenge ofphoton-counting detectors is cross-talk between
adjacent channels, induced, for instance, by fluorescent X-rays or so- called charge sharing, which occurs when charge from a single photon interaction is collected by neighbouring electrodes and therefore de- tected as several events with distributed photon energy [82,90]. Such cross talk can be mitigated by anti-coincidence logic in the ASIC [92], which sorts out pulses in adjacent detector channels within a certain time window. The size of this time window is a compromise between efficiency of the technique and the probability of discriminating against true quasi-coincident events, so called chance coincidence. Chance co- incidence together with increased complexity of the electronics reduces the maximum count rate and increases power consumption, which are the main drawbacks of anti-coincidence logic. Coincident counts may be excluded all together, added to a high-energy bin (because charge sharing occurs with higher probability for high-energy photons) [31], or treated with more advanced schemes that include summation of the pulse height from adjacent detector channels and a probability- based localization of the impulse, such as implemented in the Medipix3 chip [105].
Stryk ev detta stycke eller förkorta eller lägg in informationen i före stycke. Fokusera på applications.
== Detector technologies ==
Line 38 ⟶ 59:
Other solid-state materials, such as gallium arsenide [94], and mer-
curic iodide [95], are currently quite far from clinical implementation, but may be expanding in the future. Gas detectors have also been investigated [96], but gas is more difficult to handle than solid materials and have limited absorption efficiency.
Stryk ev detta stycke eller förkorta eller lägg in informationen i föregående stycke. Fokusera på applications.
== References ==
| |||