Abstract: The small static and composite fields occur in clinic while implementing Intensity Modulated Radiotherapy (IMRT), Volumetric Modulated Arc Therapy (VMAT), Stereotactic Radiosurgery (SRS) and Stereotactic Body radiotherapy (SBRT). These small fields are limited by constrains related to radiation beam origin and the measurement instruments available in the field. The clinical need of these fields is in achieving the homogenous and conformal dose in the tumour. The radiation beam source cannot be modified in any radiation unit until a change in its design is done. So, the range of radiation detectors like ionization chambers, scintillation detectors, silicon diodes and films have been extensively used for small field dosimetry. The plastic scintillator Exradin W2 has been tested to be the best available detector among the range of detectors for small and very small fields. The use of any detector in small field dosimetry must be accompanied by another standard detector and the data should be supported by Monte Carlo simulation studies if possible. Also, appropriate choice of Patient Specific Quality Assurance (PSQA) device is necessary to ensure the accurate dose delivery to the patients.