Editing CT scan (section)

== Research ==
[[Photon-counting computed tomography]] is a CT technique currently under development.{{As of?|date=December 2023}} Typical CT scanners use energy integrating detectors; photons are measured as a voltage on a capacitor which is proportional to the X-rays detected. However, this technique is susceptible to noise and other factors which can affect the linearity of the voltage to X-ray intensity relationship.<ref>{{Cite book |last1=Jenkins |first1=Ron |url=https://archive.org/details/quantitativexray00jenk |title=Quantitative x-ray spectrometry |last2=Gould |first2=R W |last3=Gedcke |first3=Dale |date=1995 |publisher=Dekker |isbn=978-0-8247-9554-2 |edition=2nd |location=New York |page=[https://archive.org/details/quantitativexray00jenk/page/n89 90] |chapter=Instrumentation |url-access=limited}}</ref> Photon counting detectors (PCDs) are still affected by noise but it does not change the measured counts of photons. PCDs have several potential advantages, including improving signal (and contrast) to noise ratios, reducing doses, improving spatial resolution, and through use of several energies, distinguishing multiple contrast agents.<ref>{{Cite journal |last1=Shikhaliev |first1=Polad M. |last2=Xu |first2=Tong |last3=Molloi |first3=Sabee |date=2005 |title=Photon counting computed tomography: Concept and initial results |journal=Medical Physics |volume=32 |issue=2 |pages=427–36 |bibcode=2005MedPh..32..427S |doi=10.1118/1.1854779 |pmid=15789589}}</ref><ref>{{Cite journal |last1=Taguchi |first1=Katsuyuki |last2=Iwanczyk |first2=Jan S. |date=2013 |title=Vision 20/20: Single photon counting x-ray detectors in medical imaging |journal=Medical Physics |volume=40 |issue=10 |pages=100901 |bibcode=2013MedPh..40j0901T |doi=10.1118/1.4820371 |pmc=3786515 |pmid=24089889}}</ref> PCDs have only recently become feasible in CT scanners due to improvements in detector technologies that can cope with the volume and rate of data required. As of February 2016, photon counting CT is in use at three sites.<ref>{{Cite web |date=24 February 2016 |title=NIH uses photon-counting CT scanner in patients for the first time |url=https://www.nih.gov/news-events/news-releases/nih-uses-photon-counting-ct-scanner-patients-first-time |url-status=live |archive-url=https://web.archive.org/web/20160818032611/https://www.nih.gov/news-events/news-releases/nih-uses-photon-counting-ct-scanner-patients-first-time |archive-date=18 August 2016 |access-date=28 July 2016 |website=National Institutes of Health}}</ref> Some early research has found the dose reduction potential of photon counting CT for breast imaging to be very promising.<ref>{{Cite web |title=Photon-counting breast CT measures up |url=http://medicalphysicsweb.org/cws/article/research/65633 |url-status=dead |archive-url=https://web.archive.org/web/20160727052920/http://medicalphysicsweb.org/cws/article/research/65633 |archive-date=2016-07-27 |access-date=28 July 2016 |website=medicalphysicsweb}}</ref> In view of recent findings of high cumulative doses to patients from recurrent CT scans, there has been a push for scanning technologies and techniques that reduce ionising radiation doses to patients to sub-[[Sievert|milliSievert]] (sub-mSv in the literature) levels during the CT scan process, a goal that has been lingering.<ref>{{Cite journal |last1=Kachelrieß |first1=Marc |last2=Rehani |first2=Madan M. |date=March 1, 2020 |title=Is it possible to kill the radiation risk issue in computed tomography? |url=https://www.physicamedica.com/article/S1120-1797(20)30051-X/abstract |journal=Physica Medica: European Journal of Medical Physics |volume=71 |pages=176–177 |doi=10.1016/j.ejmp.2020.02.017 |pmid=32163886 |via=www.physicamedica.com |s2cid=212692606}}</ref><ref name="Patients undergoing recurrent CT sc" /><ref name="Multinational data on cumulative ra" /><ref name="Patients undergoing recurrent CT ex" />