In clinical applications, such as PhotoDynamic Therapy, direct singlet-oxygen detection through its luminescence in the near-infrared range (1270nm)has been a challenging task due to its low emission probability and the lack of suitable single-photon detectors. Here, we propose a practical set up based on a negative-feadback avalanche diode detector that is a valiable alternative to the current state of the hart for different clinical scenarios, especially where geometric collection efficency is limited (e.g.fiber-based systems, confocal microscopy, scanning systems etc.). The proposed set up is caracterised with Rose Bengal as a standard photosensitizer and it is used to measure the singlet-oxygen quantum yield of a new set of a photosensitizer for site-selective photodynamic therapy.