Photon counting: a cutting-edge technology that revolutionizes CT examinations

Whenever a fracture, swelling or any other structural change or symptom needs to be investigated and diagnosed, the most commonly used test is CT. Roger, can you tell us more about this method?

Computed tomography is a well-known technology that has been around for more than 50 years. It is a special type of X-ray that can capture three-dimensional images of the human body. Using an X-ray tube that rotates around the body, thousands of images of an area or specific organ are taken and then combined into a three-dimensional image.

Between 1990 and 2013, CT was revolutionized by advances and developments, particularly the “slice race,” in which vendors competed to make detectors larger and larger with the goal of covering an entire organ (such as the heart) with a single scan. Since then, a great deal of time and effort has been invested in developing detectors with better image quality and reconstruction algorithms to reduce the X-ray dose to patients.

You have witnessed many innovations in CT during your career. Why do you think photon counting is different?

光子计数将有助于克服当今社会的一个重要挑战。在过去数年中，该领域的每位科学家和专家都致力于降低患者接受的辐射剂量，并利用额外的信息来提高早期诊断能力。光子计数的应用如同黑白电视跨越到彩色电视，因为这种技术提供了额外的信息，有助于更好地进行诊断。该技术还可以在显著降低辐射剂量的情况下实现更高的分辨率。根据不同临床方案，结合许多其他因素，光子计数技术能够降低40%至80%的X射线辐射剂量。

Photon counting is also committed to using the specific energy information of photons to achieve simultaneous identification and quantitative analysis of multiple tissues in the body. I am very happy to see that the technology that has been researched for many years has finally been applied to products, and the first batch of medically certified photon counting CT scanners will enter the market in 2021.

Can you explain photon counting in layman's terms?

Let me try to make it more simple. The signal detected by traditional CT is proportional to the total energy of the X-ray photons, ignoring the fact that different body or tissues have different energy attenuation. Photon counting eliminates this limitation. Because photon counting technology can measure not only the number of photons, but also the energy of these photons, it can ultimately distinguish between different substances present in the body. In other words, photon counting provides information that can be used to identify unknown variables, while traditional CT cannot.

该技术带来了除组织鉴别以外的额外优势。由于该技术下的每个单独光子对图像的贡献是相同的，光子计数也实现了图像对比度的提高。 光子计数技术受到放射科医生的高度关注的另一个方面是其显著改善的空间分辨率。根据不同CT原始设备制造商的系统参数需求，配置不同传感器，光子计数CT的空间分辨率可以达到传统CT的四倍。

In your opinion, what makes the ams-osram approach stand out?

We provide complete solutions to our customers. In addition to the readout IC that meets the stringent requirements of clinical photon counting CT at extremely low noise and power consumption, we also deliver it in an innovative buttable system in package (BSIP) form, which packages several ICs and passive components into one package. BSIP has a "tiled" feature, in other words, BSIP can be used as a tiled component extending in all directions to form the large detector area required for clinical CT. This advanced solution provides our customers with a convenient user experience and cutting-edge performance.