Radiation Protection Concepts Research Articles

RADIOECOLOGY: PAST, PRESENT, FUTURE

The article deals with issues related to the development of radioecology as an independent scientific discipline. The achievements of the past years, the studies that are currently being carried out, as well as promising areas of development in this area are analyzed. A corrected periodization of the stages of development of radioecology is proposed, taking into account the experience accumulated to date in the field of this discipline. At the initial stage (1895-1929:), empirical material was collected; at the first stage (1930-1960), the theoretical foundation was laid and radioecology was formed as an independent discipline; at the second stage (1961-1990), intensive development of radioecology was noted, and at the third stage (1991-2010) - progressive development of radioecology; the forth modern stage of radioecology development falls at the beginning of the twentieth century (2011 - present). For each stage the main scientific achievements and evolution of ideas in the field of radioecology are considered. It is postulated that at present the development of this discipline is associated with the further improvement of world nuclear technologies, the elimination of the consequences of a number of radiation incidents (the accident at the Fukushima nuclear power plant, 2011), the revision of the concept of radiation protection of the environment and a number of other provisions. Particular attention is paid to forest radioecology, one of the most important main directions of this science.

Measurement of Occupational Eye and Thyroid Radiation Doses in Pediatric Interventional Cardiologists at a Tertiary Hospital.

Background Advances in imaging techniques have led to increased utilization of imaging devices in catheterization laboratories. Invasive surgical procedures for cardiac disorders have been largely replaced by fluoroscopic cardiac catheterization. With this increase, concerns and risks associated with exposure to ionizing radiation among interventional cardiologists are growing. This study aims to measure and compare the occupational doses to the eye lens and thyroid of pediatric interventional cardiologists during different procedures in the catheterization laboratory and its significance. Methodology In this study, cardiologists wore bandanas with attached dosimeters to measure the absorbed doses to the eyes and thyroid gland. The dosimeters were collected for reading. The procedure types were also collected. In addition, the total fluoroscopy time and tube voltage of the biplane machine were measured. SPSS version 23 (IBM Corp., Armonk, NY, USA) was used to analyze the data. The characteristics of the study sample were described using simple counts and percentages, whereas means and standard deviations were used for continuous variables.Statistical significance was set at p-values <0.05. Results A total of 93 procedures were evaluated. The mean absorbed doses for all 93 procedures in both eyes and thyroid were 0.09 mGy and 0.08 mGy, respectively. A significant difference was found between the left and right eye measurements (p = 0.034), with higher doses administered to the left eye. However, no significant difference was observed between the right and left thyroid doses (p = 0.281). Significant correlations were found between the eye and thyroid doses and the procedure type (p = 0.02 and p = 0.009, respectively). Conclusions A significant amount of radiation was measured in the measurements of both organs. In addition, radiation dose measurements varied between different types of procedures. Our current results indicate the importance and necessity of applying the radiation protection concept of dose optimization.

Radiation Attitudes and Knowledge Evaluation of Associate Degree Students

The radiation that has existed throughout human history is always present in our environment, in our bodies and in space. Radiation has been used in almost every aspect of medicine, science and industry since it was discovered. Technologies that use radiation make people's lives easier, and people's lives are saved through early detection and treatment of diseases, especially in medical applications. With rapidly evolving technology, medical staff are exposed to more radiation doses due to increased radiation use in medicine. Since life without radiation is unlikely, there needs to be a sufficient level of information about radiation to protect against the harmful effects of radiation. In universities, which constitute an important part of education and training, the better the radiation knowledge of the students in the field of health, which will shape the future, the better the transfer of radiation knowledge level to future generations and at the same time to the people they serve since these students will be the health personnel of the future. Health personnel should be able to protect themselves from the harmful effects of radiation, take the necessary precautions during diagnosis and treatment, and increase their level of knowledge in this regard. In this study, it was aimed to evaluate the level of awareness of health services vocational school students, who will be health personnel in the future, towards the concept of radiation and radiation protection.

An Overview on the Alignment of Radiation Protection in Computed Tomography with Maqasid al-Shari'ah in the Context of al-Dharuriyat.

The increasing utilisation of computed tomography (CT) in the medical field has raised a greater concern regarding the radiation-induced health effects as CT imposes high radiation risks on the exposed individual. Adherence to radiation protection measures in CT as endorsed by regulatory bodies; justification, optimisation and dose limit, is essential to minimise radiation risks. Islam values every human being and Maqasid al-Shari'ah helps to protect human beings through its sacred principles which aim to fulfil human beings' benefits (maslahah) and prevent mischief (mafsadah). Alignment of the concept of radiation protection in CT within the framework of al-Dharuriyat; protection of faith or religion (din), protection of life (nafs), protection of lineage (nasl), protection of intellect ('aql) and protection of property (mal) is essential. This strengthens the concept and practices of radiation protection in CT among radiology personnel, particularly Muslim radiographers. The alignment provides supplementary knowledge towards the integration of knowledge fields between Islamic worldview and radiation protection in medical imaging, particularly in CT. This paper is hoped to set a benchmark for future studies on the integration of knowledge between the Islamic worldview and radiation protection in medical imaging in terms of other classifications of Maqasid al-Shari'ah; al-Hajiyat and al-Tahsiniyat.

A Source-Related Approach for Discussion on Using Radionuclide-Contaminated Materials in Post-accident Rehabilitation

Background: In the process of discussion on the possibility of using radionuclide-contaminated soil and debris generated by radiation disasters, a strategy for the proper management of radiation exposure protection while considering the source of the contaminated materials is necessary.Materials and Methods: The radiological protection criteria that are likely to be applied to the source-related approach based on the International Commission on Radiological Protection recommendations and the International Atomic Energy Agency safety standards are summarized. We proposed five interpretations of radiation protection to contribute to the promotion of discussion on the possibility of using a part of low-level-radionuclide-contaminated soil and debris in the post-accident rehabilitation. Interpretations I to III are based on the idea of “using a reference level to protect the public in post-accident rehabilitation,” whereas IV and V are based on the idea of “using the dose constraint to protect the public in the post-accident rehabilitation when the sources are handled in a planned activity.” The former idea is subdivided into three based on the definition of the source, which is managed by the reference level, and the latter idea is divided into two depending on whether or not additional dose from using contaminated materials is deemed acceptable.Results and Discussion: To confirm the applicability of the five interpretations presented, we suggested the concrete values of protection criteria via two feasible cases. In this case study, we proposed radiation protection by the dose constraint based on the Interpretation IV and chose 1 mSv/yr for the public and 20 mSv/yr for workers dealing with radionuclide-contaminated materials.Conclusion: We concretely and systematically demonstrated how the concept of radiation protection can be applied to the process of discussion on the possibility of using radionuclide-contaminated materials within the framework of an international system of protection. This study’s findings can provide necessary information to discuss the possibility of using radionuclide-contaminated materials as an alternative option for recovery and reconstruction after a radiation disaster from the viewpoint of radiation protection.

AWARENESS OF PAEDIATRIC RADIOLOGICAL PROTECTION AND IMAGING PARAMETERS AMONG GROUP OF SRI LANKAN RADIOGRAPHERS.

The present survey evaluated the level of awareness of radiological protection concepts and imaging parameters among Sri Lankan radiographers for the first time. The data were collected using an electronic questionnaire of 22 questions on demographic data, awareness of radiation protection concepts and imaging parameters. Only 84 out of 122 (68.8%) requested radiographers to return the questionnaire. More than 85% had ≥3 years of experience in the radiography field. The average scores for questions on best practices, imaging parameters and radiation protection were 75, 75.8 and 70.2%, respectively, with an overall score of 73.4%. Significant confusion existed on protective shielding, paediatric consenting capability, use of grids and excess X-ray field during paediatric radiography. Although the overall knowledge and awareness of participants on studied concepts were satisfactory, a continuous professional development credit system and implementation of a code of practice are required to improve the quality of radiography practice.

A Multimedia Strategy to Integrate Introductory Broad-Based Radiation Science Education in US Medical Schools.

US physicians in multiple specialties who order or conduct radiological procedures lack formal radiation science education and thus sometimes order procedures of limited benefit or fail to order what is necessary. To this end, a multidisciplinary expert group proposed an introductory broad-based radiation science educational program for US medical schools. Suggested preclinical elements of the curriculum include foundational education on ionizing and nonionizing radiation (eg, definitions, dose metrics, and risk measures) and short- and long-term radiation-related health effects as well as introduction to radiology, radiation therapy, and radiation protection concepts. Recommended clinical elements of the curriculum would impart knowledge and practical experience in radiology, fluoroscopically guided procedures, nuclear medicine, radiation oncology, and identification of patient subgroups requiring special considerations when selecting specific ionizing or nonionizing diagnostic or therapeutic radiation procedures. Critical components of the clinical program would also include educational material and direct experience with patient-centered communication on benefits of, risks of, and shared decision making about ionizing and nonionizing radiation procedures and on health effects and safety requirements for environmental and occupational exposure to ionizing and nonionizing radiation. Overarching is the introduction to evidence-based guidelines for procedures that maximize clinical benefit while limiting unnecessary risk. The content would be further developed, directed, and integrated within the curriculum by local faculties and would address multiple standard elements of the Liaison Committee on Medical Education and Core Entrustable Professional Activities for Entering Residency of the Association of American Medical Colleges.

Assessment of the awareness of radiation protection and related concepts among nursing staff mainly working in diagnostic imaging units, cath-labs and operation theatres in Sri Lanka: A survey-based study

IntroductionThis study was carried out to evaluate the awareness of radiation protection, radiation types, medical imaging equipment and radiation effects among nurses for the first time in Sri Lanka. Since nurses are involved as direct caregivers in diagnostic and therapeutic radiography and radiation treatment procedures, they need to have a good understanding of the areas mentioned above. MethodsA self-administered questionnaire was used to collect data from 391 nurses working in hospitals, clinics, and other healthcare settings. Forwarded questions gathered the participants' demographic details and assessed their awareness of radiation protection, medical imaging equipment, radiation type and radiation effects. The average score per awareness area for each demographic characteristic was calculated based on the responses. Additionally, the percentage of participants who scored above 50 and 75 was calculated for each awareness area. ResultsThe majority were female participants (81.1%) and possessed a diploma in nursing (66.0%) with 10.8 years of average work experience. 92.3%, 74.7%, 69.8% and 22.3% of the participants scored more than 50 marks for the questions related to radiation protection, medical imaging equipment, radiation type and radiation effects, respectively. The level of nursing education and prior training in radiation protection significantly influenced all awareness areas, whereas participants with a graduate qualification in nursing and with prior radiation protection training scored the highest average marks. ConclusionBased on the scores obtained, the Sri Lankan nurses have satisfactory awareness of the essential concepts related to radiation types, medical imaging equipment and radiation protection. However, there is a significant lacking of awareness of radiation effects. This can be attributed to the fact that most participants did not have any formal training in radiation protection. The results implicate that proper training in radiation protection can significantly influence awareness of radiation protection and related concepts. Therefore, it is a timely requirement to initiate short awareness programs and continuing education programs on radiation protection for nurses working in specialised radiation units. Implications for practiceThe study suggests the necessity of initiating continuous education programs for nursing staff radiation protection to overcome the awareness gaps.

Design of beam optics and radiation protection concept for NA60+ heavy-ion experiment at CERN

NA60+ is a fixed target experiment proposed in the framework of the Physics Beyond Colliders programme at CERN. It aims to precisely measure the hard and electromagnetic probes in nuclear collisions. Initially proposed for the underground cavern ECN3 with very high beam intensities, the experiment now foresees a location in the EHN1 surface hall which was shown to have a limited impact on the physics performance in spite of a significant reduction of beam intensity and detector size. The potential installation and operation of the experiment with the ion beams from the Super Proton Synchrotron (SPS) has been examined regarding detector integration, beam physics, radiation protection and shielding requirements. The integration of the experiment is considered feasible, but would require a significant reconfiguration of the existing hall infrastructure with regards to shielding and layout.

Synthesis of Thulium-yttria Nanoparticles with EPR Response

Approaches to form new materials for radiation dosimetry are essential to enhance quality assurance and quality improvement practices based on radiation protection concept. The present work reports a hydrothermal synthesis based on a relative low temperature and pressure to form thulium-yttria nanoparticles with electron paramagnetic resonance response. Thulium-yttria nanoparticles were prepared and characterized by XRD, SEM, PCS, and EPR. According to results, the hydrothermal method provided thulium-yttria nanoparticles with cubic C-type structure, mean particle size (d50) less than 160nm, and EPR response. The EPR spectra of powders exhibited two resonance peaks p1 and p2 recorded at 350 and 160mT, respectively. The enhancement of the EPR response of yttria by the use of thulium as a dopant provide meaningful parameters to advance in the formation of new rare earth based materials for radiation dosimetry.

Very-Low-Dose Radiation and Clinical Molecular Nuclear Medicine.

Emerging molecular and precision medicine makes nuclear medicine a de facto choice of imaging, especially in the era of target-oriented medical care. Nuclear medicine is minimally invasive, four-dimensional (space and time or dynamic space), and functional imaging using radioactive biochemical tracers in evaluating human diseases on an anatomically configured image. Many radiopharmaceuticals are also used in therapies. However, there have been concerns over the emission of radiation from the radionuclides, resulting in wrongly neglecting the potential benefits against little or any risks at all of imaging to the patients. The sound concepts of radiation and radiation protection are critical for promoting the optimal use of radiopharmaceuticals to patients, and alleviating concerns from caregivers, nuclear medicine staff, medical colleagues, and the public alike.

Islamic Perspective on Eye Protection from Occupational Radiation Exposures in Interventional Fluoroscopy Procedures: A Review Article

The healthcare staff in interventional fluoroscopy room are exposed to the scattered-radiation from the patient during the procedures. Excessive occupational radiation exposures to their eyes are associated with the formation of radiation-induced cataracts. Therefore, recommendations are set-up to reduce the occupation eye exposure but are often overlooked. Thus, there is a need to incorporate additional value into the recommendations. This review is conducted to incorporate the Islamic perspectives into the recommendations on the eye protection from occupational radiation exposures. Common themes were derived from the recommendations as stated in several guidelines and articles. The relevant Islamic perspective were then identified and linked. The main themes are the responsibilities of the staff in protecting their eyes and the responsibilities of the employers to ensure that their staff are protected. There were several subthemes identified for each main theme. The relevant Islamic perspectives which are related to the identified themes, eyes and concept of radiation protection were discussed in this review. The incorporation of Islamic perspective is an effort to motivate the Muslim staff and employers to see additional values and thus follow the recommendations on the eye lens protection.

CLASSIFICATION OF MEDICAL EQUIPMENT FOR ANTI-RADIATION PROTECTION.

Any collection of objects of study needs some arrangement, i. e. classification. The existing numerous classifications of antiradiation agents are built on the basis of their antiradiation effects of an integrated or differentiated nature. The work presents the chronology of the main classifications of chemical compounds that are able to protect against the shortterm and longterm effects of ionizing radiation when they are introduced into the body both before and after exposure. The change of views, trends and paradigms regarding radioprotective compounds is shown. These classifications of antiradiation medicines include radioprotectors, means of stimulating the radioresistance of the body, means of prevention and suppression of the primary reaction to irradiation, means of prevention and treatment of lesions from exposure to incorporated radionuclides, means of treatment of acute bone marrow syndrome, means of treatment of local radiation lesions. It is shown that modern concepts of radiation protection are based on fundamentally different «points of application» of groups of radioprotective agents and depend on the stage of radiation damage.

Radiation on Earth or in Space: What Does It Change?

After having been an instrument of the Cold War, space exploration has become a major technological, scientific and societal challenge for a number of countries. With new projects to return to the Moon and go to Mars, radiobiologists have been called upon to better assess the risks linked to exposure to radiation emitted from space (IRS), one of the major hazards for astronauts. To this aim, a major task is to identify the specificities of the different sources of IRS that concern astronauts. By considering the probabilities of the impact of IRS against spacecraft shielding, three conclusions can be drawn: (1) The impacts of heavy ions are rare and their contribution to radiation dose may be low during low Earth orbit; (2) secondary particles, including neutrons emitted at low energy from the spacecraft shielding, may be common in deep space and may preferentially target surface tissues such as the eyes and skin; (3) a “bath of radiation” composed of residual rays and fast neutrons inside the spacecraft may present a concern for deep tissues such as bones and the cardiovascular system. Hence, skin melanoma, cataracts, loss of bone mass, and aging of the cardiovascular system are possible, dependent on the dose, dose-rate, and individual factors. This suggests that both radiosusceptibility and radiodegeneration may be concerns related to space exploration. In addition, in the particular case of extreme solar events, radiosensitivity reactions—such as those observed in acute radiation syndrome—may occur and affect blood composition, gastrointestinal and neurologic systems. This review summarizes the specificities of space radiobiology and opens the debate as regards refinements of current radiation protection concepts that will be useful for the better estimation of risks.

Locating the Boundaries of the Nuclear North: Arctic Biology, Contaminated Caribou, and the Problem of the Threshold.

This essay is a historical–geographical account of how scientists and public health officials conceptualized and assessed northern radioactive exposures in the late 1950s and 1960s. The detection of radionuclides in caribou bodies in northern Canada both demonstrated the global reach of nuclear fallout and revealed the unevenness of toxic relations and radioactive exposures. Following the documentation of the lichen–caribou–human pathway of exposure, Canadian public health officials became increasingly concerned about the possibility of heightened radioactive exposures among Indigenous northerners. Between 1963 and 1969, scientists and officials with Canada’s Radiation Protection Division (RPD) coordinated an interdepartmental monitoring program through which they sought to determine whether the consumption of contaminated caribou meat had caused radioactive exposure levels in northern communities to exceed the officially recognized “safe limits.” In 1969, the northern monitoring program was suspended after officials determined that radionuclide body burdens had not exceeded the threshold for radioactive exposures. While the RPD emphasized its development of a technoscientific approach to measuring radioactive body burdens, the legitimacy of the monitoring program was linked directly to interdepartmental relations within Canada’s colonial northern administration. I situate the northern monitoring program within broader shifts in public health approaches to radiation protection and use Gabrielle Hecht’s concept of nuclearity to demonstrate how RPD officials employed the logic of the threshold in their assessment of radioactive exposures.

Understanding the Basis of Radiation Protection for Endovascular Procedures: Occupational and Patients

IntroductionSome concepts of radiation protection are not well understood and must be refreshed periodically. The basic knowledge that a vascular surgeon must have about radiation protection for patients and staff is summarised.ReportDiagnostic reference levels are a form of investigation into the medical exposure of patients during diagnostic and endovascular procedures that help to optimise them. Radiological quantities such as dose area product, also known as kerma area product and cumulative dose, are the most relevant to the patient. Equivalent dose, in mSv, determines the dose limits for staff. The effective dose (related to absorbed dose), also in mSv, represents the global risk of cancer and hereditary effects. For patient protection, the most important factors are fluoroscopy time, collimation, magnification, keeping the patient as near as possible to the image detector and as far as possible away from the tube, and trying to work in fluoroscope mode. Regarding occupational protection, distance, shielding, and dosimetry are the most important.DiscussionWith the increased use of endovascular procedures, radiation protection is an issue that has grown in importance. Radiation protection is based on three principles: justification; optimisation; and dose limits. Every action focused on reducing a patient's radiation dose will also reduce the dose to staff. Basic principles such as “the further away the better”, “always use a lead apron, thyroid protector, and lead glasses”, and “do not forget to wear personal dosimeters” must be remembered at all times.

Towards a new promising dosimetric material from formation of thulium-yttria nanoparticles with EPR response

Advances toward new materials for dosimetry application is essential to enhance quality assurance and quality improvement practices based on radiation protection concept. Face to this challenge the present work reports an approach to produce thulium-yttria nanoparticles with electron paramagntic resonance response by an alternative hydrothermal synthesis based on a relative low temperature and pressure. Distinct compositions of thulium-yttria nanoparticles with up to 2 at.%Tm (at.%, atomic percentage) were prepared and characterized by XRD, SEM, PCS, and EPR. The proposed synthesis method followed by thermal treatment of the precursor powder at 1100 °C for 2 h provided thulium-yttria nanoparticles with rounded shape, cubic C-type structure, and mean particle size (d50) less than 160 nm. Among all compositions formed, thulium-yttria nanoparticles prepared with 0.1%Tm presented the most remarkable EPR response. The production of fine thulium-yttria nanoparticles with EPR response supply meaningful parameters to advance in the formation of new dosimetry materials based on rare earths.

Dispersion of thulium-yttria nanoparticles to build up smart structures

The development of new materials for radiation dosimetry is a challenge to assure quality improvement practices related to radiation protection concept. On this context, colloidal stability provides conditions to build up smart structured materials from bottom-up perspective. The present work reports zeta potential characterization of thulium-yttria nanoparticles in aqueous medium. Thulium-yttria nanoparticles formed by a relative low temperature hydrotermal synthesis were characterized by XRD, PCS, and SEM. The stability of particles in aqueous medium was evaluated by electrophoretic mobility measurements, followed by zeta potential calculation. The results revealed that the isoelectric point of thulium-yttria suspensions shifted in accordance with thulium concentration from pH 8.5 (“pure” yttria) to pH 9.2 (2at.%Tm). Besides, most suspensions could be stabilized at pH 10.5, presenting zeta potential values around 30 mV. These results are substantial parameters to advance toward new materials for radiation dosimetry.

Paradigma baru konsep proteksi radiasi dalam pemeriksaan radiologi kedokteran gigi: dari ALARA menjadi ALADAIP

Objectives: This article is aimed to widely share information and discuss further about the emerging transformation theories of the traditional radiation protection concept of ALARA into some more modern proposed concepts, particularly in dentomaxillofacial radiology. &#x0D; Literature Review: The concept of radiation protection in the use of X-ray modalities in the medical field has developed along with the development of science over past decades. The concept of ALARA which has been widely known for a long time and is used as a basic of theory or main reference in radiation protection policies in several countries or at the international level now becomes a traditional, conservative and invalid principle to apply. There are several emerging theories which are considered to be more valid and representative to replace the ALARA principle. &#x0D; Conclusion: Newer concepts of radiation protection that have developed, ALADAIP, are considered to be more precise and specific to be the main principle of radiation protection at this time, especially in the field of dentomaxillofacial radiology.

Radioprotective effects of induced astronaut torpor and advanced propulsion systems during deep space travel

Background. Human metabolic suppression is not a new concept, with 1950s scientific literature and movies demonstrating its potential use for deep space travel (Hock, 1960). An artificially induced state of metabolic suppression in the form of torpor would improve the amount of supplies required and therefore lessen weight and fuel required for missions to Mars and beyond (Choukèr et al., 2019). Transfer habitats for human stasis to Mars have been conceived (Bradford et al., 2018). Evidence suggests that animals, when hibernating, demonstrate relative radioprotection compared to their awake state. Experiments have also demonstrated relative radioprotection in conditions of hypothermia as well as during sleep (Bellesi et al., 2016 and Andersen et al., 2009). Circadian rhythm disrupted cells also appear to be more susceptible to radiation damage compared to those that are under a rhythmic control (Dakup et al., 2018).An induced torpor state for astronauts on deep space missions may provide a biological radioprotective state due to a decreased metabolism and hypothermic conditions. A regular enforced circadian rhythm might further limit DNA damage from radiation.The As Low As Reasonably Achievable (A.L.A.R.A.) radiation protection concept defines time, distance and shielding as ways to decrease radiation exposure. Whilst distance cannot be altered in space and shielding either passively or actively may be beneficial, time of exposure may be drastically decreased with improved propulsion systems. Whilst chemical propulsion systems have superior thrust to other systems, they lack high changes in velocity and fuel efficiency which can be achieved with nuclear or electric based propulsion systems.Radiation toxicity could be limited by reduced transit times, combined with the radioprotective effects of enforced circadian rhythms during a state of torpor or hibernation.Objectives. 1. Investigate how the circadian clock and body temperature may contribute to radioprotection during human torpor on deep space missions.2. Estimate radiation dose received by astronauts during a transit to Mars with varying propulsion systems.Methods. We simulated three types of conditions to investigate the potential radioprotective effect of the circadian clock and decreased temperature on cells being exposed to radiation such that may be the case during astronaut torpor. These conditions were:- Circadian clock strength: strong vs weak.- Light exposure: dark-dark vs light-dark cycle- Body temperature: 37C vs hypothermia vs torpor.We estimated transit times for a mission to Mars from Earth utilizing chemical, nuclear and electrical propulsion systems. Transit times were generated using the General Mission Analysis Tool (GMAT) and Matlab. These times were then input into the National Aeronautics and Space Administration (NASA) Online Tool for the Assessment of Radiation In Space (OLTARIS) computer simulator to estimate doses received by an astronaut for the three propulsion methods.Results. Our simulation demonstrated an increase in radioprotection with decreasing temperature. The greatest degree of radioprotection was shown in cells that maintained a strong circadian clock during torpor. This was in contrast to relatively lower radioprotection in cells with a weak clock during normothermia. We were also able to demonstrate that if torpor weakened the circadian clock, a protective effect could be partially restored by an external drive such as lighting schedules to aid entrainment i.e.: Blue light exposure for periods of awake and no light for rest timesFor the propulsion simulation, estimated transit times from Earth to Mars were 258 days for chemical propulsion with 165.9mSv received, 209 days for nuclear propulsion with 134.4mSv received and 80 days for electrical propulsion with 51.4mSv received.Conclusion. A state of torpor for astronauts on deep space missions may not only improve weight, fuel and storage requirements but also provide a potential biological radiation protection strategy. Moreover, maintaining a controlled circadian rhythm during torpor conditions may aid radioprotection. In the not too distant future, propulsion techniques will be improved to limit transit time and hence decrease radiation dose to astronauts. Limiting exposure time and enhancing physiological radioprotection during transit could provide superior radioprotection benefits compared with active and passive radiation shielding strategies alone.