Eye dose assessment and management: overview

BRAIN AND EYE AS POTENTIAL TARGETS FOR IONIZING RADIATION IMPACT: PART II - RADIATION CEREBRO/OPHTALMIC EFFECTS IN CHILDREN, PERSONS EXPOSED IN UTERO, ASTRONAUTS AND INTERVENTIONAL RADIOLOGISTS

BACKGROUND

Ionizing radiation (IR) can affect the brain and the visual organ even at low doses, while provoking cognitive, emotional, behavioral, and visual disorders. We proposed to consider the brain and the visual organ as potential targets for the influence of IR with the definition of cerebro-ophthalmic relationships as the «eye-brain axis».

OBJECTIVE

The present work is a narrative review of current experimental, epidemiological and clinical data on radiation cerebro-ophthalmic effects in children, individuals exposed in utero, astronauts and interventional radiologists.

MATERIALS AND METHODS

The review was performed according to PRISMA guidelines by searching the abstract and scientometric databases PubMed/MEDLINE, Scopus, Web of Science, Embase, PsycINFO, Google Scholar, published from 1998 to 2021, as well as the results of manual search of peer-reviewed publications.

RESULTS

Epidemiological data on the effects of low doses of IR on neurodevelopment are quite contradictory, while data on clinical, neuropsychological and neurophysiological on cognitive and cerebral disorders, especially in the left, dominant hemisphere of the brain, are nore consistent. Cataracts (congenital - after in utero irradiation) and retinal angiopathy are more common in prenatally-exposed people and children. Astronauts, who carry out longterm space missions outside the protection of the Earth's magnetosphere, will be exposed to galactic cosmic radiation (heavy ions, protons), which leads to cerebro-ophthalmic disorders, primarily cognitive and behavioral disorders and cataracts. Interventional radiologists are a special risk group for cerebro-ophthalmic pathology - cognitivedeficits, mainly due to dysfunction of the dominant and more radiosensitive left hemisphere of the brain, andcataracts, as well as early atherosclerosis and accelerated aging.

CONCLUSIONS

Results of current studies indicate the high radiosensitivity of the brain and eye in different contingents of irradiated persons. Further research is needed to clarify the nature of cerebro-ophthalmic disorders in different exposure scenarios, to determine the molecular biological mechanisms of these disorders, reliable dosimetric support and taking into account the influence of non-radiation risk factors.

The new radiation protection framework since 2019 - Implementation in Germany and comparison of some aspects in seven European countries

PURPOSE

 The implementation of EU Directive 2013/59 EURATOM (EU-BSS) of 2014 led to a reorganization of radiation protection legislation in Germany in the form of a new radiation protection law Strahlenschutzgesetz (StrlSchG) of 2017 and a new radiation protection ordinance Strahlenschutzverordnung (StrlSchV) of 2018. For application of ionizing radiation in medicine these changes affect radiology, nuclear medicine and radiotherapy. A comparison between the old and the new legal system analyses changes that are relevant for diagnostic and interventional radiology. For the important new regulation of unintended exposures, a comparison is made with the implementation of Art. 63 EU-BSS in 7 European countries.

MATERIAL AND METHODS

 The provisions of the Röntgenverordnung (RöV) and the old Strahlenschutzverordnung (StrlSchV alt), which were valid until 2018, are compared with the new legislation of StrlSchG and StrlSchV for changes in radiation protection for patients, the population and occupational radiation protection of staff members. The occupational dose limit of the eye lens was reduced. The reduction by a factor of 7.5 results in new requirements for radiation protection equipment. New requirements in teleradiology are compared with the previous regulation, as well as the necessary involvement of medical physics experts (MPE) in high dose procedures, such as CT and fluoroscopic interventions. The regulation for unintended exposures of the German StrlSchV are analyzed in terms of their reporting criteria.

RESULTS

 The principles of medical radiation protection in Germany have not changed as a result of the new radiation protection legislation from 2019 onwards. However, there are a number of changes and new requirements that must be considered and implemented. Important points are e. g. new regulations on teleradiology, early detection of diseases in asymptomatic individuals and reporting of unintended exposure of patients. As all new regulations are no longer found in only one single regulation, both knowledge of the StrlSchG and the StrlSchV are necessary.

KEY POINTS

  · The EU Directive 2013/59 EURATOM (EU-BSS) was transposed into the new German radiation protection law 2018. · The basic regulations of the RöV and old StrlSchV remain unchanged. · Newly added regulations must be known and implemented in practice. · Many regulations of the EU-BSS are so vaguely formulated that they allow a wide scope for national implementation.

CITATION FORMAT

· Loose R, Wucherer M, Walz M et al. The new radiation protection framework since 2019 - Implementation in Germany and comparison of some aspects in seven European countries. Fortschr Röntgenstr 2020; 192: 1036 - 1045.

Assessment of the Annual Eye Lens Dose for Cardiologists During Interventional Procedures Using Anthropomorphic Phantoms and mEyeDose_X Tool

OBJECTIVES

In this study, eye lens dose measurements were performed using two anthropomorphic phantoms simulating the cardiologist and patient during interventional procedures.

BACKGROUND

Interventional procedures known as areas with high potential risk and the cardiologists can receive relatively high doses to their eyes.

METHODS

This study was comprised of both phantom and computer simulations. Thermoluminescent dosimeters (TLDs) and mEyeDose_X tool were used to measure and calculate eye lens doses for the cardiologist. 144 TLDs measurements were performed using cardiac protocol for three angiographic projections: anterior-posterior (AP), left anterior oblique 90° (LAO90) and left anterior oblique 45° with cranial 30° (spider) angulations. All cine and fluoroscopy modes including the projections used in this study performed with and without protection tools.

RESULTS

The annual equivalent doses with protective tools using mEyeDose_X were found to be 1.831 and 1.424 mSv/year, whereas the values using phantom were found to be 2.204 and 1.802 mSv/year for the lens of lift and right eye respectively.

CONCLUSION

The annual doses reported in this study are almost comparable to other studies performed on interventional cardiology (IC) procedures. The highest dose rate in the lens was 20.21 ± 0.015 mSv/h without protective tools in cine mode for spider projection. Cardiologists may therefore easily exceed the lens dose limit if protective tools are not used.

SHOULD PERSONNEL OF NUCLEAR MEDICINE DEPARTMENTS USE PERSONAL DOSIMETERS FOR EYE LENS DOSE MONITORING?

Staff at nuclear medicine departments receive doses of ionising radiation higher than the staff of radiotherapy and radiology departments, with the exception of interventional radiologists. Due to the updated lower occupational exposure limit for the lens of the eye, we measured eye exposure in workers of the Nuclear Medicine Department, Pomeranian Medical University in Szczecin, Poland. EYE-D™ dosimeters were used for 3 months by 10 employees working with sources of ionising radiation. Personal dosimeters also measured the exposure of the whole body and hands. The 3-month dose equivalents for the lens of the eye in the employees was 0.20-0.72 mSv. Staff at NMD PMU do not require regular routine eye lens dose monitoring. Eye lens doses were well within the new annual limit of 20 mSv. Doses to the whole body may be used as an indicator of the eye lens doses in the monitored department.

The International Atomic Energy Agency action plan on radiation protection of patients and staff in interventional procedures: Achieving change in practice

INTRODUCTION

The International Atomic Energy Agency (IAEA) organized the 3rd international conference on radiation protection (RP) of patients in December 2017. This paper presents the conclusions on the interventional procedures (IP) session.

MATERIAL AND METHODS

The IAEA conference was conducted as a series of plenary sessions followed by various thematic sessions. "Radiation protection of patients and staff in interventional procedures" session keynote speakers presented information on: 1) Risk management of skin injuries, 2) Occupational radiation risks and 3) RP for paediatric patients. Then, a summary of the session-related papers was presented by a rapporteur, followed by an open question-and-answer discussion.

RESULTS

Sixty-seven percent (67%) of papers came from Europe. Forty-four percent (44%) were patient studies, 44% were occupational and 12% were combined studies. Occupational studies were mostly on eye lens dosimetry. The rest were on scattered radiation measurements and dose tracking. The majority of patient studies related to patient exposure with only one study on paediatric patients. Automatic patient dose reporting is considered as a first step for dose optimization. Despite efforts, paediatric IP radiation dose data are still scarce. The keynote speakers outlined recent achievements but also challenges in the field. Forecasting technology, task-specific targeted education from educators familiar with the clinical situation, more accurate estimation of lens doses and improved identification of high-risk professional groups are some of the areas they focused on.

CONCLUSIONS

Manufacturers play an important role in making patients safer. Low dose technologies are still expensive and manufacturers should make these affordable in less resourced countries. Automatic patient dose reporting and real-time skin dose map are important for dose optimization. Clinical audit and better QA processes together with more studies on the impact of lens opacities in clinical practice and on paediatric patients are needed.

OCULAR ORGAN DOSE ASSESSMENT OF NUCLEAR MEDICINE WORKERS HANDLING DIAGNOSTIC RADIONUCLIDES

The dose distribution in the ocular organs of nuclear medicine workers during the handling of diagnostic radionuclides was assessed via simulation in virtual space. The cornea and lenses received the highest dose, and the dose distribution tended to be proportional to the gamma-ray energy emitted from the radiation source being handled. Moreover, calculations on the dose-reduction effects of eyewear protectors for the eyes of the workers showed that the effects were inversely proportional to the emitted gamma-ray energy, with the dose-reduction effect decreasing in the order of 201Tl, 123I, 99mTc, 67Ga, 111In and 18F. Among the considered sources, the dose-reduction effect was significant for sources that emit relatively less energy, namely 123I, 201Tl and 99mTc, while it was lower for the remaining sources, namely 18F, 111In and 67Ga.

OCCUPATIONAL DOSE ASSESSMENT IN INTERVENTIONAL CARDIOLOGY IN SERBIA

The objective of this work is to assess the occupational dose in interventional cardiology in a large hospital in Belgrade, Serbia. A double-dosimetry method was applied for the estimation of whole-body dose, using thermoluminescent dosemeters, calibrated in terms of the personal dose equivalent Hp(10). Besides the double-dosimetry method, eye dose was also estimated by means of measuring ambient dose equivalent, H*(10), and doses per procedure were reported. Doses were assessed for 13 physicians, 6 nurses and 10 radiographers, for 2 consequent years. The maximum annual effective dose assessed was 4.3, 2.1 and 1.3 mSv for physicians, nurses and radiographers, respectively. The maximum doses recorded by the dosemeter worn at the collar level (over the apron) were 16.8, 11.9 and 4.5 mSv, respectively. This value was used for the eye lens dose assessment. Estimated doses are in accordance with or higher than annual dose limits for the occupational exposure.