“…The small sensitive volume of MO Skin is around 4.8 × 10 −6 mm 3 , which provides the high spatial resolution that is suitable for small field dosimetry . Some commercial silicon detectors used for QA in radiotherapy include Delta4 (Scandidose, Sweden), ArcCheck (Sun Nuclear, Melbourne, USA), and OCTAVIUS (PTW, Germany). These tools, however, unfortunately do not have enough spatial resolution for SRS/SRT where sub‐millimeter spatial resolution is required in the penumbral region.…”