Use of Ionizing Radiation in the Health Sector

and consequently producing is widely applied hospitals. In the health area, the use of ABSTRACT Ionizing Radiation (IR) is widely used in different applications. The energy capable of moving electrons in some materials has been used in different human activities, including in the health sector. Technological advances and diversity in the use of IR are expressed in the treatment of tumors, in diagnostic imaging and in the monitoring of invasive procedures. The performance of procedures with application of IR requires structural adequacy and procedures to guarantee the radiological protection of the patient and the source operator. The present work sought to carry out a narrative review of the literature on ionizing radiation, with the inclusion of definitions and concepts and the presentation of theories and evidence that helped to emphasize the topic of interest. International initiatives have been pioneering in the investigation of security and dosimetry parameters, however, there are still technical and conceptual gaps that do not allow the full implementation of international standards. The radioprotection theme needs to be widely discussed so that professionals who are currently exposed, even without operating radioactive sources, have access to adequate care procedures and guarantees. Continuing educational actions represent an important strategy for reducing health problems, including cancer, and improving workers’ quality of life.

has brought many benefits, such as its application in diagnostic tests and in different therapies [2,5], due to the great capacity of penetration in different surfaces.
X-rays can be produced by an artificial source that accelerates electrons, followed by their collision against a lead plate. During the collision, there is a loss of kinetic energy by the electrons, causing heat production (most of the ionization process) and X-rays. From artificial mechanisms for the production of ionizing radiation, X-rays, γ-rays, as well as radioactive particles (isotopes) can be used in health as: (1) Radiotherapy -use of X-rays, γ and beams of electrons to treat tumors by eliminating tumor cells and consequent growth inhibition; (2) Brachytherapy -localized use of radiotherapy for specific types and locations of tumors, in which radioactive sources emitting low and medium energy gamma radiation are used; (3) Medicines containing radioisotopes -use of radioactive particles with guaranteed preferential deposition in target organs and which are administered orally or injectable to patients with tumors, such as the use of iodine isotopes for the treatment of thyroid cancer. Diagnostic exams, such as radiographs (use of X-rays or γ-rays), computed tomography (use of X-rays), mammography (use of low-energy X-ray beam) and mapping with radiopharmaceuticals (use of radioactive markers) are also widely performed in the health field [1].
The use of ionizing radiation in health services applies external and internal sources. While the external source is related to exposure to X-ray equipment [2], for example, the internal sources are related to radiopharmaceutical therapy [1], with the consumption of contaminated water and / or food or even dermal or respiratory contact with radionucleotides. According to the International Agency for Research on Cancer (IARC) all types of ionizing radiation are considered carcinogenic to humans and therefore classified in group I [2]. The absorption of ionizing radiation by the body contributes to the production of free radicals [4]. According to José Alencar Gomes da Silva National Cancer Institute (INCA), the main acute effects on the human species, due to exposure for a short period of time, usually to high doses, are nausea, weakness, hair loss, skin burns or decreased organic function. In general, cancer patients and those treated with radiation often experience these types of side effects to ongoing treatment [6]. However, in cases of accidents, for example, exposure can occur to very high doses of radiation, capable of causing damage so intense that it can contribute to death [4].
Exposure to small doses of radiation, over time, also contribute to human illness. The mechanism of action involved is the production of changes in DNA (initiation step with epigenetic mechanisms participation) that contribute to the development of different neoplasms such as cancer of the salivary gland, esophagus, stomach, colon, lung, bones, breast, bladder, kidney, skin, brain and Central Nervous System (CNS), thyroid and leukemia. These types of cancer are described in the literature due to chronic exposure to X-rays and γ-rays [2,6]. Despite the benefits, ionizing radiation exposes multidisciplinary health teams to the associated risks. In this way, workers from medical institutions and or laboratories who perform their occupational activities operating equipment that emit radiation are exposed to these carcinogenic agents [6]. In Brazil, the National Nuclear Energy Commission limits occupational exposure to an average of 20 millisievert (mSv) over a period of 5 years, but in one year, this exposure cannot exceed 50 mSv [7], with the intention of minimizing risk to workers' health. The risk for the development of cancer depends on the dose, duration of exposure, age at which the exposure took place and tissue sensitivity to the carcinogenic effects of radiation [6].
In Latin America, tests involving ionizing radiation are performed by nurses, doctors and radiology technicians, but only 64% of the 10 largest cardiac intervention centers in Latin America use dosimeters. Of these, only 36% know how to interpret the results [8]. The lack of knowledge about the risks of radiation is also evident in Intensive Care Units (ICU). In situations in which the patient cannot move, the equipment is taken to the bed and the examinations are carried out without the adoption of adequate protection measures [9], putting everyone in the environment at risk. Clinical and epidemiological studies show deleterious effects on human health such as mutations, cancer, congenital abnormalities, cardio and cerebrovascular diseases, cataracts and others, even when exposed to low doses of ionizing radiation [10]. In hospital facilities whose space for hospitalization of patients is reduced, there may be an increase in the exposure of professionals in the sector, in addition to exposure to unqualified professionals and patients. In this respect, the multidisciplinary team that assists patients in inpatient units, specifically those in intensive care, ends up being exposed due to the performance of radiological exams in the patient's bed. Although mobile devices have a configuration for safe operation in inpatient units [7,11], the dimensioning and adaptation of environments can represent risk to the worker and the patient. In this context, epidemiological studies with populations exposed to radiotherapy, show an increased risk for the development of cancer, when the exposure occurs above 100 mSv [4]. Exposures between 50 and 100 mSv also showed a risk for children hospitalized in ICUs for cancer control [4]. With regard to epidemiological studies with workers in the health sector, these are scarce, whether these studies with operators of a source of ionizing radiation, or even with a multidisciplinary health team.
As the application of ionizing radiation in health increases every day, the continuous planning and development of actions to be adopted in different situations of exposure to ionizing radiation is extremely urgent, considering the risks involved in human health, but also in the environment. These measures gain importance when reviewing national experiences, such as the Cesium-137 accident, and international ones, realizing that the technical and logistical capacity of organizations, cities, states and countries may not be sufficient without prior planning [5]. The perception of the need to expand radioprotection measures was the target of international investigations in the search for standardization of acceptable parameters and protection measures. Although the movement in the search for standardization of protection measures has generated training courses and the establishment of collaboration networks, it is believed that it is necessary to expand the discussion and regulation. Hankin & Jones (2020) [12] evaluated the impact of educational intervention on radiation protection in health professionals at different levels and realized that the intervention was effective in increasing knowledge on the topic, but found great variability of knowledge among participants in addition to recognize the absence of studies that assess the impact of this knowledge in the long term [12].
Thus, the efforts made by the European dosimetry group represent an international mobilization to expand knowledge about the risks and environmental parameters to be considered. The group has approximately 600 researchers who work with ionizing radiation dosimetry and develop research projects, educational and training actions, in addition to making interlaboratory comparisons [13]. Noteworthy is the fact that the actions developed need to consider and at the same time enable safety for health workers, regardless of whether they are responsible for operating ionizing radiation sources or if the exposure of health workers occurs in environments shared with multidisciplinary teams, as in the ICU.
Thus, the perception of the importance of continuing educational actions, but involving all possible exposed workers, will enable the adoption of safe practices and the use of equipment that minimizes the exposure of health professionals.

Conclusion
The research on radioprotection and dimensioning of the effects of ionizing radiation in health professionals needs to be expanded and its proportionality inverted. In view of the applications of this type of radiation during work activity, professionals may be exposed to risks not yet dimensioned in Brazil. Educational actions play an important role in prevention; however, there are still no data on changing attitudes after long periods without training. It is believed that international efforts need to be made and directed towards

Conflict of Interest
Thera are any economic or conflict of interest.