# State-of-the-Art Mobile Radiation Detection Systems for Different Scenarios
## 4 Mobile Radiation Detection Systems
### Radiation Detection and Gamma Spectrometry
#### 4.2.2 Airborne Survey
They studied the effects of the flight parameters, such as the height, inclination of the detection system relative to the soil, and the detection time in the detection efficiency and minimum detectable activity (MDA). [PERSON] et al. [169] proposed a small ducted fan UAV (AVID EDF-8) to carry a lightweight radiation sensor (Teviso RD3024--PIN Diode) for radiation detection (gamma and beta) and mapping in a nuclear emergency scenario. It was highlighted that, for critical time tasks, a path planning algorithm should be developed, which could change the search for minimum or maximum dose values (instead of an exhaustive search pattern), e.g., to find a safe path for rescues or to find hotspots. Figure 8: Examples of detectors coupled to air-based platforms: (**a**) Multi-rotor UAV with a Cadmium Zinc Telluride (CZT) and a single-point light detection and ranging (LiDAR) mounted in a gimbal. Reproduced, with permission, from Reference [159]; published by Elsevier, 2016, under the terms of the [[https://creativecommons.org/licenses/by/4.0/CC](https://creativecommons.org/licenses/by/4.0/CC)]([https://creativecommons.org/licenses/by/4.0/CC](https://creativecommons.org/licenses/by/4.0/CC)) BY 4.0 license. (**b**) Multi-rotor UAV with a SIGMA-50 CsI(Tl) detector and a single-point laser rangefinder. Reproduced, with permission, from Reference [164]; published by Elsevier, 2018, under the terms of the [[https://creativecommons.org/licenses/by/4.0/CC](https://creativecommons.org/licenses/by/4.0/CC)]([https://creativecommons.org/licenses/by/4.0/CC](https://creativecommons.org/licenses/by/4.0/CC)) BY 4.0 license. (**c**) Multi-rotor UAV with two Bismuth Germanate (BGO) detectors. Reproduced, with permission, from Reference [166]; copyright Elsevier (2018). [PERSON] et al. [166] showed the possibility of using a multi-rotor to carry a relatively large volume detection system to environmental monitoring, particularly uranium anomalies near the village of Trebsko, Czech Republic. The detection system is composed by two 103 cm\({}^{3}\) BGO gamma-ray spectrometers (Figure 8c), with a total weight of 4 kg (batteries included), and is characterized by an energy resolution of 13.6% at 662 keV. The combined detectors have a total sensitivity of 160% compared to the standard 350 cm\({}^{3}\) NaI(Tl) crystal and each BGO has about 300 times more sensitivity than a 1 cm\({}^{3}\) CZT detector. With a speed of 1 m/s and heights between 5-40 m, it was possible to collect the same number of counts per unit distance as a standard airborne survey (manned aircraft). However, limitations, like the flight autonomy of only 16 min (related to the payload weight) and speed, make the mini-airborne gamma-ray spectrometry impracticable to regional surveys. The authors also argue that, despite their good energy resolution, the Labr\({}_{3}\)(Ce) scintillation detector and the semiconductors CZT or CdTe described above are not appropriate to measure low radiation fields (comparable to background values), the first one because of the crystal intrinsic activity by \({}^{138}\)La and the other two due to their small sensitivity (small volume sensors). [PERSON] et al. [8] also proposed a detection system coupled to a multi-rotor for dose rate measurements, air sampling, and radiation mapping. One GM (0.5 kg) and an air sampler module for aerosol collection (<1.5 kg) were used. The devices main features are: Modularity (detector and air sampler in modules), customized control software, hibernate capability (system activates when necessary), easy to clean (if contamination occur), easy to integrate on different UAVs, possible parallel operation of UAVs to improve map efficiency, and online radiation map functionality (data available in real-time). One way to overcome the flight time limitations (range) and the low speed of multi-rotors, as well as the lack of spatial resolution on the data collected by detection systems coupled to manned aircraft (e.g., flight altitude regulatory restrictions), is by the use of an unmanned fixed-wing as the transport platform.