IEC 63121:2020适用于用于检测放射性物质非法贩运的车载移动系统（也称为移动系统或移动监测器）；这些仪器还可以用于保护重大公共活动和对大面积进行快速筛查。这些车载移动系统由一个或多个安装在车辆上的辐射探测器组成，例如主要在公共道路上行驶的汽车或面包车。本文件不适用于安装在其他类型车辆上的检测系统，例如飞机、直升机、火车或船只。本文件涵盖的车载检测系统设计用于在车辆行驶时检测放射源。 它们也可以用作扫描静止或移动物体的静止监视器。车载移动系统检测伽马辐射，并且可以包括中子检测和/或发射伽马射线的放射性核素的识别。

IEC 63121:2020 applies to vehicle-mounted mobile systems (also known as mobile systems or mobile monitors) that are used for the detection of illicit trafficking of radioactive materials; these instruments may also be used for protection of major public events and for rapid screening of large areas. These vehicle-mounted mobile systems consist of one or more radiation detectors mounted in a vehicle, e.g., car or van, which travels predominantly on public roads. This document does not apply to detection systems mounted in other types of vehicles, e.g., planes, helicopters, trains, or boats. Vehicle-mounted detection systems covered by this document are designed to detect radioactive sources while the vehicle is in motion. They may also be used as stationary monitors that scan stationary or moving objects. Vehicle-mounted mobile systems detect gamma radiation and may include neutron detection and/or identification of gamma-ray emitting radionuclides.