When selecting a dosimeter, you must prioritize the Detection Type (Alpha, Beta, Gamma, or X-ray) and the Sensor Technology, such as Geiger-Muller (GM) tubes, Scintillation counters, or Semiconductor sensors. Ensure the device offers a wide Measurement Range (typically from 0.01μSv/h to 10mSv/h) and high Sensitivity. For professional environments, look for features like Real-time Dose Rate monitoring, Cumulative Dose tracking, and Adjustable Alarm Thresholds (audible, visual, and vibration) to ensure immediate user protection.