Development of shielding evaluation and management program for O-ring type linear accelerators.

The shielding parameters can vary depending on the geometrical structure of the linear accelerators (LINAC), treatment techniques, and beam energies. Recently, the introduction of O-ring type linear accelerators is increasing. The objective of this study is to evaluate the shielding parameters of new type of linac using a dedicated program developed by us named ORSE (O-ring type Radiation therapy equipment Shielding Evaluation). The shielding evaluation was conducted for a total of four treatment rooms including Elekta Unity, Varian Halcyon, and Accuray Tomotherapy. The developed program possesses the capability to calculate transmitted dose, maximum treatable patient capacity, and shielding wall thickness based on patient data. The doses were measured for five days using glass dosimeters to compare with the results of program. The IMRT factors and use factors obtained from patient data showed differences of up to 65.0% and 33.8%, respectively, compared to safety management report. The shielding evaluation conducted in each treatment room showed that the transmitted dose at every location was below 1% of the dose limit. The results of program and measurements showed a maximum difference of 0.003 mSv/week in transmitted dose. The ORSE program allows for the shielding evaluation results to the clinical environment of each institution based on patient data.

RFPID: development and 3D-printing of a female physical phantom for whole-body counter.

Whole-body counters (WBC) are used in internal dosimetry forin vivomonitoring in radiation protection. The calibration processes of a WBC set-up include the measurement of a physical phantom filled with a certificate radioactive source that usually is referred to a standard set of individuals determined by the International Commission on Radiological Protection (ICRP). The aim of this study was to develop an anthropomorphic and anthropometric female physical phantom for the calibration of the WBC systems. The reference female computational phantom of the ICRP, now called RFPID (Reference Female Phantom for Internal Dosimetry) was printed using PLA filament and with an empty interior. The goal is to use the RFPID to reduce the uncertainties associated within vivomonitoring system. The images which generated the phantom were manipulated using ImageJ®, Amide®, GIMP®and the 3D Slicer®software. RFPID was split into several parts and printed using a 3D printer in order to print the whole-body phantom. The newly printed physical phantom RFPID was successfully fabricated, and it is suitable to mimic human tissue, anatomically similar to a human body i.e., size, shape, material composition, and density.

Synthesis of the European ALARA network 20th workshop 'ALARA for interventional radiology and nuclear medicine'.

The European as low as reasonably achievable(ALARA) network regularly organises workshops on topical issues in radiation protection (RP). The topic of the 20th workshop was: 'ALARA for interventional radiology (IR) and nuclear medicine (NM)'. The objective was to examine the challenges faced when applying the optimisation principle (ALARA) in IR and NM and to consider how ALARA could be better implemented for patient and staff exposures. This memorandum provides a synthesis of the workshop sessions, and recommendations coming from the working groups discussion. Parallels are drawn with the recommendations arising from the 13th EAN workshop on 'ALARA and the medical sector (2011)' to consider how the optimisation challenges in IR and NM have evolved over the past decade. Current levels of exposure are presented along with operational practice and the challenges and opportunities for improvement, both in monitoring and practice. Whilst RP challenges remain, the application of ALARA appears more established in IR compared with experiences reported in 2011. The application of ALARA to emerging technologies in the NM setting is in need of further development to ensure that RP is considered at all stages in the development process of new radiopharmaceuticals. Besides the obvious technical and operational aspects, the importance of education and training, human factors and broadly the RP 'culture' were deemed fundamental to the success of the application of ALARA and where further emphasis is needed. All concerned parties, medical physics experts (MPEs), radiation protection experts, clinical staff, manufacturers and regulators have a role to play in the application of ALARA and this is discussed in the memorandum. Many of the recommendations from the 13th EAN workshop remain applicable today and overlap with the recommendations arising from the 20th workshop. This should prompt attention given that the use of IR and the development of novel radiopharmaceuticals for NM is only anticipated to increase with time.

Secondary proton buildup in space radiation shielding.

The risk posed by prolonged exposure to space radiation represents a significant obstacle to long-duration human space exploration. Of the ion species present in the galactic cosmic ray spectrum, relativistic protons are the most abundant and as such are a relevant point of interest with regard to the radiation protection of space crews involved in future long-term missions to the Moon, Mars, and beyond. This work compared the shielding effectiveness of a number of standard and composite materials relevant to the design and development of future spacecraft or planetary surface habitats. Absorbed dose was measured using Al2O3:C optically stimulated luminescence dosimeters behind shielding targets of varying composition and depth using the 1 GeV nominal energy proton beam available at the NASA Space Radiation Laboratory at the Brookhaven National Laboratory in New York. Absorbed dose scored from computer simulations performed using the multi-purpose Monte Carlo radiation transport code FLUKA agrees well with measurements obtained via the shielding experiments. All shielding materials tested and modeled in this study were unable to reduce absorbed dose below that measured by the (unshielded) front detector, even after depths as large as 30 g/cm2. These results could be noteworthy given the broad range of proton energies present in the galactic cosmic ray spectrum, and the potential health and safety hazard such space radiation could represent to future human space exploration.

Society and Nuclear Energy: What Is the Role for Radiological Protection?

ABSTRACT: The harm that society expects from ionizing radiation does not match experience. Evidently there is some basic error in this assumption. A reconsideration based on scientific principles shows how simple misunderstandings have exaggerated dangers. The consequences for society are far-reaching. The immediate impact of ionizing radiation on living tissue is destructive. However, this oxidative damage is similar to that produced during normal metabolic activity where the subsequent biological reaction is not only protective but also stimulates enhanced protection. This adaptation means that the response to oxidative damage depends on past experience. Similarly, social reaction to a radiological accident depends on the regulations and attitudes generated by the perception of previous instances. These shape whether nuclear technology and ionizing radiation are viewed as beneficial or as matters to avoid. Evidence of the spurious damage to society caused by such persistent fear in the second half of the 20 th century suggests that these laws and attitudes should be rebased on evidence. The three stages of radiological impact-the initial physical damage, the subsequent biological response, and the personal and social reaction-call on quite different logic and understanding. When these are confused, they lead to regulations and public policy decisions that are often inept, dangerous, and expensive. One example is when the mathematical rigor of physics, appropriate to the immediate impact, is misapplied to the adaptive behavior of biology. Another, the tortured historical reputation of nuclear technology, is misinterpreted as justifying a radiological protection policy of extreme caution.Specialized education and closed groups of experts tend to lock in interdisciplinary misperceptions. In the case of nuclear technology, the resulting lack of independent political confidence endangers the adoption of nuclear power as the replacement for fossil fuels. In the long term, nuclear energy is the only viable source of large-scale primary energy, but this requires a re-working of public understanding.

Replace the Linear No-threshold Model with a Risk-informed Targeted Approach to Radiation Protection.

ABSTRACT: The linear no-threshold (LNT) model may be useful as a simple basis for developing radiation protection regulations and standards, but it bears little resemblance to scientific reality and is probably overly conservative at low doses and low dose rates. This paper is an appeal for a broader view of radiation protection that involves more than just optimization of radiation dose. It is suggested that the LNT model should be replaced with a risk-informed, targeted approach to limitation of overall risks, which include radiation and other types of risks and accidents/incidents. The focus should be on protection of the individual. Limitation of overall risk does not necessarily always equate to minimization of individual or collective doses, but in some cases it might. Instead, risk assessment (hazards analysis) should be performed for each facility/and or specific job or operation (straightforward for specialized work such as radiography), and this should guide how limited resources are used to protect workers and the public. A graded approach could be used to prioritize the most significant risks and identify exposure scenarios that are unlikely or non-existent. The dose limits would then represent an acceptable level of risk, below which no further reduction in dose would be needed. Less resources should be spent on ALARA and tracking small individual and collective doses. Present dose limits are thought to be conservative and should suffice in general. Two exceptions are possibly the need for a lower (lifetime) dose limit for lens of the eye for astronauts and raising the public limit to 5 mSv y -1 from 1 mSv y -1 . This would harmonize the public limit with the current limit for the embryo fetus of the declared pregnant worker. Eight case studies are presented that emphasize how diverse and complex radiation risks can be, and in some cases, chemical and industrial risks outweigh radiation risks. More focus is needed on prevention of accidents and incidents involving a variety of types of risks. A targeted approach is needed, and commitments should be complied with until they are changed or exemptions are granted. No criticism of regulators or nuclear industry personnel is intended here. Protection of workers and the public is everyone's goal. The question is how best to accomplish that.

Science-informed Policy Making for Protecting People and the Environment from Radiation.

ABSTRACT: The process to arrive at the radiation protection practices of today to protect workers, patients, and the public, including sensitive populations, has been a long and deliberative one. This paper presents an overview of the US Environmental Protection Agency's (US EPA) responsibility in protecting human health and the environment from unnecessary exposure to radiation. The origins of this responsibility can be traced back to early efforts, a century ago, to protect workers from x rays and radium. The system of radiation protection we employ today is robust and informed by the latest scientific consensus. It has helped reduce or eliminate unnecessary exposures to workers, patients, and the public while enabling the safe and beneficial uses of radiation and radioactive material in diverse areas such as energy, medicine, research, and space exploration. Periodic reviews and analyses of research on health effects of radiation by scientific bodies such as the National Academy of Sciences, National Council on Radiation Protection and Measurements, United Nations Scientific Committee on the Effects of Atomic Radiation, and the International Commission on Radiological Protection continue to inform radiation protection practices while new scientific information is gathered. As a public health agency, US EPA is keenly interested in research findings that can better elucidate the effects of exposure to low doses and low dose rates of radiation as applicable to protection of diverse populations from various sources of exposure. Professional organizations such as the Health Physics Society can provide radiation protection practitioners with continuing education programs on the state of the science and describe the key underpinnings of the system of radiological protection. Such efforts will help equip and prepare radiation protection professionals to more effectively communicate radiation health information with their stakeholders.

The Impact of the Linear No-threshold Hypothesis on Litigation.

ABSTRACT: As the basis of radiation safety practice and regulations worldwide, the linear no-threshold (LNT) hypothesis exerts enormous influence throughout society. This includes our judicial system, where frivolous lawsuits are filed alleging radiation-induced health effects caused by negligent companies who subject unwitting victims to enormous financial and physical harm. Typically, despite the lack of any supporting scientific basis, these cases result in enormous costs to organizations, insurance companies, and consumers.

A Revised System of Radiological Protection Is Needed.

ABSTRACT: The system of radiological protection has been based on linear no-threshold theory and related dose-response models for health detriment (in part related to cancer induction) by ionizing radiation exposure for almost 70 y. The indicated system unintentionally promotes radiation phobia, which has harmed many in relationship to the Fukushima nuclear accident evacuations and led to some abortions following the Chernobyl nuclear accident. Linear no-threshold model users (mainly epidemiologists) imply that they can reliably assess the cancer excess relative risk (likely none) associated with tens or hundreds of nanogray (nGy) radiation doses to an organ (e.g., bone marrow); for 1,000 nGy, the excess relative risk is 1,000 times larger than that for 1 nGy. They are currently permitted this unscientific view (ignoring evolution-related natural defenses) because of the misinforming procedures used in data analyses of which many radiation experts are not aware. One such procedure is the intentional and unscientific vanishing of the excess relative risk uncertainty as radiation dose decreases toward assigned dose zero (for natural background radiation exposure). The main focus of this forum article is on correcting the serious error of discarding risk uncertainty and the impact of the correction. The result is that the last defense of the current system of radiological protection relying on linear no-threshold theory (i.e., epidemiologic studies implied findings of harm from very low doses) goes away. A revised system is therefore needed.

The teaching of Radiology in other university studies.

After the implementation of the European Space for Higher Education, the contents of the Radiology and Physical Medicine Area that were taught in the Medicine Degree have also been incorporated into the new degrees of Dentistry, Nursing, Physiotherapy, Podiatry, and, to a lesser extent, Pharmacy, Occupational Therapy, Logopedia, and Biomedical Engineering As a whole, the basic concepts of radiology and radiological protection are taught in Murcia in 5 different degrees with a total of 52.5 ECTS credits, participating in the training of 1219 students each academic year. This incorporation in the new degrees has tripled the number of subjects in which undergraduate teaching is taught, and doubled both the number of ECTS credits and the number of undergraduate students to whom it directs its training work. Thus, given the possible creation of new university degrees in the near future (Diagnostic Imaging and Radiotherapy Technicians), it would be necessary to involve a greater number of accredited professionals, from different specialties, and to optimize teaching resources (bibliography, material teacher, clinical cases, etc.,) for its usefulness in the different subjects that share similar contents.

Radiation protection in a cohort of healthcare workers: knowledge, attitude, practices, feelings and IR-exposure in French hospitals.

The number of healthcare workers occupationally exposed to ionizing radiation (IR) is increasing every year. As health effects from exposure to low doses IR have been reported, radiation protection (RP) in the context of occupational activities is a major concern. This study aims to assess the compliance of healthcare workers with RP policies, according to their registered cumulative dose, profession, and perception of radiation self-exposure and associated risk. Every healthcare worker from one of the participating hospitals in France with at least one dosimetric record for each year 2009, 2014, and 2019 in the SISERI registry was included and invited to complete an online questionnaire including information on the worker's occupational exposure, perception of IR-exposure risk and RP general knowledge. Hp(10) doses were provided by the SISERI system. Multivariate logistic regressions were used. Dosimeter wearing and RP practices compliance were strongly associated with 'feeling of being IR-exposed' (OR = 3.69, CI95% 2.04-6.66; OR = 4.60, CI95% 2.28-9.30, respectively). However, none of these factors was associated with RP training courses attendance. The main reason given for non-compliance is unsuitability or insufficient numbers of RP devices. This study provided useful information for RP policies. Making exposed workers aware of their own IR-exposure seems to be a key element to address in RP training courses. This type of questionnaire should be introduced into larger epidemiological studies. Dosimeter wearing and RP practices compliance are associated to feeling being IR-exposed. RP training courses should reinforce workers' awareness of their exposure to IR.

A Review of Recent Low-dose Research and Recommendations for Moving Forward.

ABSTRACT: The linear no-threshold (LNT) model has been the regulatory "law of the land" for decades. Despite the long-standing use of LNT, there is significant ongoing scientific disagreement on the applicability of LNT to low-dose radiation risk. A review of the low-dose risk literature of the last 10 y does not provide a clear answer, but rather the body of literature seems to be split between LNT, non-linear risk functions (e.g., supra- or sub-linear), and hormetic models. Furthermore, recent studies have started to explore whether radiation can play a role in the development of several non-cancer effects, such as heart disease, Parkinson's disease, and diabetes, the mechanisms of which are still being explored. Based on this review, there is insufficient evidence to replace LNT as the regulatory model despite the fact that it contributes to public radiophobia, unpreparedness in radiation emergency response, and extreme cleanup costs both following radiological or nuclear incidents and for routine decommissioning of nuclear power plants. Rather, additional research is needed to further understand the implications of low doses of radiation. The authors present an approach to meaningfully contribute to the science of low-dose research that incorporates machine learning and Edisonian approaches to data analysis.

Alerts to improve occupational protection during Interventional Radiology. More attention is needed for simple but frequent procedures.

Occupational protection could be improved in interventional radiology. The monthly personal dosimetry cannot alert on some occupational doses with anomalous values for certain procedures. Active electronic personal dosimeters linked wireless to a dose management system (DMS), allow for the measurement of occupational doses per procedure, integrating this information with patient dose indicators and with technical and geometrical conditions of the procedures. We analysed around 3100 occupational dose values for individual procedures collected during the last two years, in an interventional radiology laboratory of a University Hospital and two groups, with patient doses higher than 100 Gy.cm2, and lower than 30 Gy.cm2. An unshielded reference dosimeter located at the C-arm registers the ambient dose equivalent (ADE) per procedure to be compared with the personal dose equivalent (PDE) over the apron. The ratio between both values PDE/ADE is a good indication of occupational protection. Alerts for occupational protection optimisation are suggested. For the full sample, 8.4 % of occupational doses measured over the protective apron of the interventionists were higher than 100 µSv and 3.8 % higher than 200 µSv per procedure. Occupational protection for complex procedures (>100 Gy.cm2) had median values of 46 µSv for PDE and 3.3 % for PDE/ADE. However, for simple procedures, (<30 Gy.cm2) the median values were 10 µSv and 28.4 %. This last percentage is 9 times higher than the value for complex procedures. This lack of protection should be corrected and the need to reduce some occupational doses reinforced in radiation protection training programmes for interventionists.

Prospective dose monitoring using a manual dose management system: experience in brain computed tomography from a tertiary hospital in Nigeria.

A manual radiation dose management system was developed to track the radiation dose and scan parameters of patients for brain computed tomography (CT). Radiation dose in volume computed tomography dose index (CTDIvol) and dose length product (DLP) were monitored to identify procedures that may require optimisation using notification values. The data were analysed and compared with national and international diagnostic reference levels (DRLs). A total of 596 brain CTs were monitored and grouped as <1: 36, 1-<5: 38, 5-<10: 25, 10-<15: 31 and adult: 466. The CTDIvol notification value identified the following number of examinations having high CTDIvol in <1 y: 1, 1-<5: 1, 5-<10: 0, 10-<15: 0 and adult (>15): 11. Furthermore, the DLP notification values identified the following examinations with high DLP in <1 y: 1, 1-<5:1, 5-<10:1, 10-<15: 1 and adults (>15): 18. The established local paediatric DLP DRLs were 2-3 times higher than the international paediatric DLP DRLs. This calls for a total protocol review and optimisation considering the local CT practices for paediatric imaging.

Patient perspectives on ionising radiation exposure from computed tomography in Saudi Arabia: a knowledge and perception study.

The objective of this study was to evaluate patient knowledge and understanding of ionising radiation and dosage, as well as the accompanying risks related to computed tomography scans. A total of 412 outpatients who underwent computed tomography (CT) scans were surveyed to assess their understanding of radiation dose and exposure risks. CT was correctly classified as an ionising radiation by 56.8% of the respondents. More than half of the patients reported that a CT scan increases the probability of inducing cancer. Awareness of varying radiation doses in different CT exams was noted in 75.2% of patients, but only 21.4% reported having discussions with their physician about radiation dose. Gender, age and employment were significantly correlated with knowledge levels. The survey findings indicate a limited understanding of the hazards associated with ionising radiation used in CT scans, highlighting a need for increased awareness and education on radiation protection to ensure informed consent.

Potential risk assessment: a model for quality evaluation in fluoroscopy-guided interventional procedures.

This study presented a model applied for potential risk assessment in an interventional radiology setting. The model of potential risk assessment (MARP) consisted of the creation of a scale of indicators ranging from 0 to 5. The radiation levels were categorized according to gender, kind of procedure, value of kerma air product (Pka), and accumulated radiation dose (mGy). The MARP model was applied in 121 institutions over 8 y. A total of 201 656 patient radiation doses (Dose-area product and accumulated kerma) data were launched into the system over time, with an average of 22 406 doses per year. In the context of the workers (cardiologists, radiographers, and nurses) monitored during the MARP application, 8007 cases (with an average of 890 per year) of occupational radiation doses were recorded. This study showed a strategy for quality evaluation in fluoroscopy using a model with a compulsory information system for monitoring safety.