Generally, medical Gamma Camera are based on the Anger principle. These cameras use a scintillator block coupled to a bulky array of photomultiplier tube (PMT). To simplify this, we designed a new integrated CMOS image sensor in order to replace bulky PMT photodetetors. We studied several photodiodes sensors including current mirror amplifiers. These photodiodes have been fabricated using a CMOS 0.6 micrometers process from Austria Mikro Systeme (AMS). Each sensor pixel in the array occupies respectively, 1mm x 1mm area, 0.5mm x 0.5mm area and 0.2mm 0.2mm area with fill factor 98 % and total chip area is 2 square millimeters. The sensor pixels show a logarithmic response in illumination and are capable of detecting very low green light emitting diode (less than 0.5 lux) . These results allow to use our sensor in new Gamma Camera solid-state concept.