4-Side Buttable System-In-Package The AS5920M is a 72x24 pixel, four-side buttable module solution for photon counting applied for spectral computed tomography detectors. The 1728-channel Buttable System-In-Package (BSIP) integrates three AS5920 photon counting ICs as well as passive components. During a CT scan, the device counts the X-ray photon proportional to the energy, 5 energy levels can be set to discriminate the energy of incoming photon.