This thesis describes the practical application of scintillation detector techniques and focuses on how to enhance their potential for use in the new concept spectroscopy method called HELIOS, combination of the magnetic resonance image (MRI) and positron emission tomography (PET) called PET-MRI system, and other medical applications. Optically coupled LaBr3(Ce) with Hamamatsu avalanche photomultiplier first tested inside a (nearly) 1T magnetic field, resulting in the field does not have an adverse impact on the performance of the detector. A magnetic resonance image was also successfully obtained when a scintillation detector system interfaced with a homogeneous magnetic field inside the brain phantom, but detector current influenced on the MR image. In Chapter 2, there are the further investigations into various scintillation detector systems such as Phoswich-PMT, CsI and LYSO coupled with SensL position sensitive SiPM. SensL new-generation blue sensitive B and C series SiPMs have an innovative silicon photomultiplier structure resulting in an additional readout signal for fast timing application. SensL SiPMs with the large photosensitive area studied regarding their characteristics and coincidence time measurement. According to the measurement result, the dependencies of bias voltage, temperature, gain and dark current were consistent with the literature. Coincidence time resolution was gradually improved from 512 ps to 276 ps for 6 mm C-SiPM by changing set-up and adding transformer in the circuit. A novel antimatter detector system developed for medical applications. GEANT4 based GATE 7.0 simulation was used for optimum scintillator thickness investigation to measure the activity directly from positrons rather than gamma radiation without any interference between scintillator and radiopharmacy. Various detector designs successfully tested for microfluidic chip and blood counter applications (measured volume from 94μ to 0.11μ ). The half-life of 68 Ga was experimentally calculated to be 62.11±8 minutes resulting in agreement with the literature if they overlap within their uncertainties. The new detector is cost-effective, based on very simple working principle, user-friendly, easy to modify into another system, and achievable nanoscale volume. Therefore, the objective of this research is to aid significantly in deciding a final design for the detector system before serial manufacturing and before applying for the patent.