| 词条 | Photon counting |
| 释义 |
Photon counting is a technique in which individual photons are counted using some single-photon detector (SPD). The counting efficiency is determined by the quantum efficiency and any electronic losses that are present in the system. Many photodetectors can be configured to detect individual photons, each with relative advantages and disadvantages,[1][2] including a photomultiplier, geiger counter, single-photon avalanche diode, superconducting nanowire single-photon detector, transition edge sensor, or scintillation counter. Charge-coupled devices can also sometimes be used. ApplicationsSingle-photon detection is useful in many fields including fiber-optic communication, quantum information science, quantum encryption, medical imaging, light detection and ranging, DNA sequencing, astrophysics, and materials science.[1]MedicineIn radiology, one of the major disadvantages of X-ray imaging modalities is the negative effects of ionising radiation. Although the risk from small exposures (as used in most medical imaging) is thought to be very small, the radiation protection principle of "as low as reasonably practicable" (ALARP) is always applied. One way of reducing exposures is to make X-ray detectors as efficient as possible, so that lower doses can be used for the same diagnostic image quality. Photon counting detectors could help, due to their ability to reject noise more easily, and other advantages compared to conventional integrating (summing) detectors.[3][4] Commercial photon counting mammography machines have been produced. Although such systems are not widespread, there is some evidence of their ability to produce comparable images at lower doses than other digital mammography systems with flat panel detectors.[5][6] Photon-counting computed tomography is another key area of interest, where the ability to discriminate between photon energies could significantly improve the ability to distinguish tissue types when reconstructing an image.[7][4] Measured quantitiesThe number of photons observed per unit time is the photon flux. The photon flux per unit area is the photon irradiance if the photons are incident on a surface, or photon exitance if the emission of photons from a broad-area source is being considered. The flux per unit solid angle is the photon intensity. The flux per unit source area per unit solid angle is photon radiance. SI units for these quantities are summarized in the table below. {{SI photon units}}See also
References1. ^1 {{cite press release |author= |title=High Efficiency in the Fastest Single-Photon Detector System |url=https://www.nist.gov/pml/div686/manufacturing/high-efficiency-single-photon-detector.cfm |publisher=National Institute of Standards and Technology |date=February 19, 2013 |access-date=2018-10-11}} {{physics-stub}}2. ^{{cite journal |url=https://www.nature.com/articles/nphoton.2009.230 |first=RH |last=Hadfield |title=Single-photon detectors for optical quantum information applications |journal=Nature Photonics |volume=3 |issue=12 |page=696 |date=2009|doi=10.1038/nphoton.2009.230 |bibcode=2009NaPho...3..696H }} 3. ^{{cite book |last1=Shikhaliev |first1=M |editor1-last=Iwanczyk |editor1-first=Jan S. |title=Radiation Detectors for Medical Imaging |date=2015 |publisher=CRC Press |location=Boca Raton, FL |isbn=9781498766821 |page=2-21 |url=https://books.google.com/books?id=7wYZCwAAQBAJ |language=en |chapter=Medical X-ray and CT Imaging with Photon-Counting Detectors}} 4. ^1 {{cite journal |last1=Taguchi |first1=Katsuyuki |last2=Iwanczyk |first2=Jan S. |title=Vision 20/20: Single photon counting x-ray detectors in medical imaging |journal=Medical Physics |date=12 September 2013 |volume=40 |issue=10 |pages=100901 |doi=10.1118/1.4820371 |pmc=3786515}} 5. ^{{cite journal |last1=McCullagh |first1=J B |last2=Baldelli |first2=P |last3=Phelan |first3=N |title=Clinical dose performance of full field digital mammography in a breast screening programme |journal=The British Journal of Radiology |date=November 2011 |volume=84 |issue=1007 |pages=1027–1033 |doi=10.1259/bjr/83821596 |pmc=3473710}} 6. ^{{cite journal |last1=Weigel |first1=Stefanie |last2=Berkemeyer |first2=Shoma |last3=Girnus |first3=Ralf |last4=Sommer |first4=Alexander |last5=Lenzen |first5=Horst |last6=Heindel |first6=Walter |title=Digital Mammography Screening with Photon-counting Technique: Can a High Diagnostic Performance Be Realized at Low Mean Glandular Dose? |journal=Radiology |date=May 2014 |volume=271 |issue=2 |pages=345–355 |doi=10.1148/radiol.13131181}} 7. ^{{cite book |last1=Iwanczyk |first1=Jan S |last2=Barber |first2=W C |last3=Nygård |first3=Einar |last4=Malakhov |first4=Nail |last5=Hartsough |first5=N E |last6=Wessel |first6=J C |editor1-last=Iniewski |editor1-first=Krzysztof |title=Electronics for Radiation Detection |date=2018 |publisher=CRC Press |isbn=9781439858844 |url=https://books.google.com/books?id=kgJ-DwAAQBAJ&pg=PT51 |language=en |chapter=Photon-Counting Energy-Dispersive Detector Arrays for X-Ray Imaging}} 3 : Optical metrology|Photonics|Particle detectors |
| 随便看 |
|
开放百科全书收录14589846条英语、德语、日语等多语种百科知识，基本涵盖了大多数领域的百科知识，是一部内容自由、开放的电子版国际百科全书。