Photon starvation

Last revised by Andrew Murphy on 23 Mar 2023

Photon starvation is one source of streak artifact which may occur in CT. It is seen in high attenuation areas, particularly behind metal implants. Because of high attenuation, insufficient photons reach the detector. During the reconstruction process, the noise is greatly magnified in these areas leading to characteristic streaks in the image 3.

In some applications, namely low dose CT protocols, the increased noise due to photon starvation is normally encountered as a trade-off between low patient radiation dose and acceptable image quality. The artifact can be reduced by automatic tube current modulation (increased mAs) and adaptive filtration via applying the local filter. Use of iterative reconstruction techniques can also significantly reduce image noise caused by this artifact 2,3

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Cases and figures

  • Figure 1: increased noise due to photon starvation (low dose protocol)
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  • Figure 2: due to morbid obesity
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  • Figure 3: due to shoulders
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