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I'm going to talk about photon counting CT physics,

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where a period of time from the time CT were developed back in 1974,

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we have seen some time at every other time we

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see when the CT technology is almost saturated, and we are done

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with all the application, we have seen CT technology

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expanding and a new evolution has happened.

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You can see instances when from the time CT were started in

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1974, around 1990, when we thought

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CT technology was saturated, the introduction of helical CT

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revolutionized the field. The helical CT was gaining lot of

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attention, lot of utilization, and beginning to see some

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limitation. That's when the multi-detector CT were

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invented. Multi-detector CT were introduced back in

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1998. We saw many new

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application for the strength in the field of CT.

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So from 1998 onwards until around 2015,

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'16, the multi-detector CT expanded, new

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applications started, such as the advancement, the cardiac

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CT, hybrid CT technology,

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the perfusion CT, dual energy

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CT. All this was possible because of multi-detector CT.

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Then we saw the introduction of photon counting CT, which has

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now further brought in new excitement.

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So the question is: what is photon counting CT?

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How does that differ from the conventional CT scanners?

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The way to distinguish is to examine how the signals are

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detected, and that can be done in two ways: to

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understand the current CT technology detector, which we call it

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as energy integrating detectors,

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and the new detectors called as the photon counting detectors.

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Let's examine this one.

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So the photon counting CT is touted as an emerging

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technology with the potential to dramatically change clinical

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CT because it uses new

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energy-resolving X-ray detectors with mechanism

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that differs substantially from those of conventional energy

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integrating detector.

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This photon counting detector can count the number of incoming

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photons and measure photon energy appropriately.