Radiation is one of the forms of energy. The study of ionizing radiation and its interaction with matter, focusing on the energy absorbed, is known as radiological physics. Radiation dosimetry quantifies that energy.
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As the detection and measurement of radiation are based on detecting and measuring its effects in a medium, the history of radiation detectors is closely linked to the discovery of radiation and its effects.
Wilhelm Rontgen discovered X-rays, Henri Becquerel discovered radioactivity, and the Curies discovered radium in the 1890s, marking the beginning of radiological physics. Radium and X-rays both quickly rose to prominence in medical instruments.
Radiation is divided into particle radiation (electrons, alpha particles, neutrons, etc.) and electromagnetic radiation (X-rays and γ-rays) based on physical characteristics.
Why Is It Important to Monitor Radiation?
Ionizing radiation exposure causes cell death and mutagenesis, and the clinical effects vary depending on the dose and the affected body part. Therefore, carcinogenesis must be reduced in patients receiving radiotherapy, those exposed to diagnostic radiation, and members of specific professional groups.
By escalating therapies, early and late effects of radiotherapy could be prevented or treated, enhancing the quality of life and increasing the likelihood that cancer can be cured.
In a research published in The British Journal of Radiology, the researcher divided the effects of ionizing radiation exposure into five main categories:
- Type I: Early radiation effects: Cellular death and tissue depletion followed by stem cell proliferation.
- Type II: Early radiation effects/reactive gene activation: Inflammation from radiation is caused by early radiation effects/reactive gene activation, including cellular and tissue dysfunction, increased vascular permeability, tissue edema, growth factors and cytokines production by white blood cells, as well as endothelial cells and fibroblasts.
- Type III: Tissue disorganization and late radiation damage: The early Type II effects can progress to permanent tissue disorganization and dysfunction, with the proliferation of fibroblasts and vessels. Clinical signs of edema, fibrosis, and telangiectasia are then seen if the radiation damage to fibroblasts and vessels (or other cells of connective origin) is serious enough. Necrosis may result from severe vascular component destruction.
- Type IV: stochastic effects: If mutations accumulate in the somatic cell genome following radiation exposure, they may be passed to progeny. This could happen to all epithelial or connective tissue cells, resulting in solid tumors, or it could happen to blood cells, causing hematological malignancies.
- Type V: Effects radiation on bystanders: Although this effect has been known for a long time, it has only recently become the focus of a significant amount of research to determine its molecular processes. This effect results from radiation harming cells in an organ or the entire body that have not been exposed to radiation directly.
Where Are Radiation Sensors Used?
Radiation sensors are important in almost every aspect of life as even UV radiation from sun exposure can cause skin irritation, burns, and may even lead to skin cancer. However, in some sectors, such as medicine and defense, using sensors is crucial, and negligence can result in severe consequences. For example, X-rays produced during medical imaging and α, β, and γ radiations produced in a nuclear plant must be detected and controlled.
Proper protective gear needs to be worn in such facilities. Radiation exposure in space also needs to be detected, and health effects on astronauts must be considered.
How Can Sensors Be Used to Monitor Radiation?
Radiation sensors or detectors transform a portion of the energy lost by incident radiation into an electrical signal that can be measured. In other terms, a radiation detector is a gadget that can detect a specific kind of radiation.
It is important to note that no detector is radiation-sensitive to all radiation types. Instead, the energy range in which the detector is intended to operate determines which sensors are best for a specific application. However, certain radiation detectors are called nucleonic detectors since they can detect both nuclear particles and electromagnetic radiation.
A radiation dosimeter experiences a change in its properties after being subjected to radiation with enough energy, which can be expressed visually, electrically, thermally, mechanically, or physiologically. Ionization occurs due to their interactions with the radiation, which affects the dosimeter's properties.
Dosimetry is concerned with the techniques for calculating the radiation dosage that material has absorbed or bodily components. Personnel with the potential of being exposed to hazardous radiation wears wearable dosimeters on their skin or clothing.
Commercial Examples of Radiation Sensors
Vendors including Veridose (Cardinal Health Management Services, USA), Isorad (Sun Nuclear, USA), T60010 (PTW, Germany), and EDP (Scanditronix Wellhofer, Sweden) provide a variety of diode dosimeters for sale. In addition, to detect X and Gamma radiation doses, BARC has created another gadget, DIGIDOSE - a digital pocket radiation dosimeter. It is based on a Silicon (Si) rectifier diode that is widely available and operates at a modest reverse bias of approximately 4 V.
There is also a commercially available TLD-based ring-style dosimeter by ISRN Dosimetry Lab that may be worn on the finger. Here, the film (lithium fluoride) creates luminescence dependent on its exposure to ionizing radiation, the number of trapped electrons and the dose that the dosimeter received to determine the luminescence.
Additionally, Mirion provides a range of dosimeters for wearable and individual monitoring. The Android (phone) platform receives information from the Dosime device about the ionizing radiation around a user through Bluetooth or WiFi.
Future Outlook of Radiation Sensors to Detect Radiation
Future research and applications in UV wearables have a lot of potential for various user types and population groups. Therefore, it is crucial to provide precise outputs during outdoor exercise relevant to personal variables, for instance, skin type and prior skin cancer.
Furthermore, these sensors have enormous potential to close measurement gaps for co-occurring activities at various body sites, UV exposures and skin damage, and behavior linkages such as sun-protective behaviors.
The most highly recommended electronic sensors for human research investigations are the Scienterra and Shade sensors, and they have previously been employed in many research studies.
References and Further Reading
Koukourakis, M I, (2014). Radiation damage and radioprotectants: new concepts in the era of molecular medicine. The British Journal of Radiology. Available at: https://doi.org/10.1259/bjr/16386034
Dhanekar, S., Rangra, K., (2021) Wearable Dosimeters for Medical and Defence Applications: A State of the Art Review. Adv. Mater. Technol. 6, 2000895.Available at: https://doi.org/10.1002/admt.202000895
Mirzaei, A., Huh, JS., Kim, S.S. et al. (2018) Room Temperature Hard Radiation Detectors Based on Solid State Compound Semiconductors: An Overview. Electron. Mater. Lett. 14, 261–287.Available at: https://doi.org/10.1007/s13391-018-0033-2
K.A. Pradeep Kumar, G.A. Shanmugha Sundaram, B.K. Sharma, S. Venkatesh, R. Thiruvengadathan, (2020). Advances in gamma radiation detection systems for emergency radiation monitoring. Journal of Nuclear Engineering and Technology, 52, 2151-2161, Available at: https://doi.org/10.1016/j.net.2020.03.014
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