Unsealed Radioactive Sources Research Articles

Extremity dosimetry for exposed workers in positron emission tomography in Bosnia and Herzegovina.

Occupational exposure in Bosnia and Herzegovina is regulated by the national regulation on radiation protection for occupational and public exposure. All radiation workers are required to be monitored using whole body passive thermoluminescent dosemeters and, in case of non-uniform external exposures, by dosemeters that would indicate dose to the most affected body parts. Exposed workers are almost exclusively employed in the medical field, and some of them work in nuclear medicine departments where they handle unsealed radioactive sources. Introduction of the positron emission tomography-computed tomography (PET-CT) in two largest clinical centers in the country was expected to cause the increase of equivalent doses to hands received by staff handling the positron emitting radionuclides. Hence, routine monitoring of finger doses became a necessity. The purpose of this study was to evaluate the available data on monitoring with ring dosemeters during PET-CT procedure in two hospitals in Bosnia and Herzegovina and compare them with other practices in the nuclear medicine department, as well as with the results of monitoring in other countries. In general, results confirm that effective doses, as well as equivalent doses to hands, are well below annual dose limits. Finger dosemeters have been proven to be an invaluable asset in the incidental situations that sometimes occur in nuclear medicine departments. Different number of patients and differences in injection methodologies are identified as a possible source of differences between doses in two hospitals. Overall, routine evaluation of doses to hands provides a sound basis for possible optimization processes, as well as confirmation of good practices.

Effectiveness of polymeric gloves in radioprotection against contamination in nuclear medicine

When handling unsealed radioactive sources, radiological protection attention must be taken to avoid unnecessary exposure and radioactive contaminations, and an important and necessary practice to prevent such contaminations is the use of gloves when handling these sources. The present work aimed to determine the effectiveness of contamination protection provided by different types of disposable polymeric gloves used in Nuclear Medicine Service in Clinic Hospital of Porto Alegre, testing the main radiopharmaceuticals used at this site: [99mTc]sodium pertechnetate, [18F]FDG and [131I]sodium iodide. The analysis was performed using the wipe test inside gloves intentionally contaminated on the outside with these radiopharmaceuticals. The radiation detector used to measure the contamination was a NaI(Tl) scintillator well-type counter. The results indicate that three types of gloves analyzed protect the user from [99mTc]sodium pertechnetate and [18F]FDG contamination, for permanence times with the glove after contamination for up to 15 min (interval tested). For [131I]sodium iodide, gloves are completely effective in protection as long as they are used for a time interval after contamination of the external surface of up to: Latex – 5 min; Vinyl – 5 min; Nitrile – 10 min. Among them, the nitrile glove are the most effective, since contamination was not observed on the inner face for times equal to or less than 10 min; and, for an interval of 15 min, the percentage of permeation obtained was lower than the other two types: 3.3 times lower than vinyl glove permeation and 1.3 times lower of the latex glove permeation. It was also possible to estimate the skin dose rate due to contamination caused by iodine permeation for each glove case and time tested.

Extremity exposure of nuclear medicine workers: results from an EANM and EURADOS survey.

Extremity exposure during the handling of unsealed radioactive sources is a matter of concern for nuclear medicine workers. Next to 99mTc and 18F, other radiopharmaceuticals have seen an increase in their use over the last decade. However, limited information on their impact on extremity dose is available. This study aimed to gain insight into the status of extremity exposure and dose monitoring in Europe. A survey was conducted at the end of 2020 among the European Association of Nuclear Medicine community. It contained 24 questions considering department characteristics, worker tasks, dosimeter use, typical worker extremity dose, department workload for selected radionuclides (99mTc, 18F, 68Ga, 177Lu, 90Y) and protective measures. A total of 106 replies were received, 92% of which were from Europe. About half of the respondents were from academic hospitals. Ninety-nine departments implement extremity dose monitoring for a total of 1335 workers. Most workers (95%) wear a ring dosimeter, generally on the non-dominant hand, and 44% on the index finger. Monthly doses were generally low (median values at different ring position: 0.4-1.8 mSv), although higher doses were reported (20.8-38.8 mSv). About 1/3 of workers performed the full task range (preparation, dispensing, and administration). Administration is associated with significantly lower extremity doses. Interestingly, no correlation between department workload and collective dose was found. The adoption of vial and syringe shielding, as well as distance tools, was common. The workers dispensing 99mTc without syringe shielding or PET nuclides without automated system received a significantly higher dose. Handling 68Ga, 177Lu and 90Y did not appear to have an impact on the reported doses. Protective measures play a significant role in lowering extremity doses, while department workload and more recently introduced radionuclides seem not to be major dose determinants.

Root Cause Analysis of Na131I Contamination.

Establishing a cause-and-effect relationship for an adverse event is one of the key steps in preventing them and involves multiple people, resources, and steps, thus requiring a root cause analysis. Here, we describe a root cause analysis performed in the nuclear medicine department for an event involving Na131I contamination. Oral administration of Na131I in a capsule minimizes the risk of contamination and spills. However, the patient must be able to swallow a capsule. Na131I in capsule form is currently in widespread use for treatment of hyperthyroidism and thyroid cancer. Na131I in liquid form is rarely available immediately on demand and must be ordered at least 24-48 h in advance of the planned administration. The events leading to the incident, immediate remedial steps taken, and subsequent root cause analysis are described. The corrective actions taken after the root cause analysis, as well as the subsequent effectiveness of these actions, are mentioned. There may be one or multiple causes for an adverse event. It is important to identify the root cause. Corrective actions derived from the root cause can help prevent similar adverse events in the future. Therapeutic procedures in nuclear medicine involve unsealed radioactive sources, further adding a separate layer of immediate steps and reporting to the root cause analysis itself.

Development of a model for registration and notification of accidents and incidents in nuclear medicine

Nuclear medicine (NM) is a medical speciality that uses unsealed radioactive sources involving several handling procedures with some critical points before, during, and after the examination and therapies performed, requiring special attention to the occurrence of a possible accident or incident over the course of the clinical routine. The accidents and incidents in NM can involve actors such as workers, patients, the public or caregivers, and even the environment. Although expected, the number of occurrences and their nature are not well understood due to the absence of a Brazilian reporting tool for incidents or accidents. This paper aims to develop a web-based NM incident and accident notification system named SINMED (NM Notification System). Specific forms were developed in an offline system in html5 language with an online system interface according to the Google Forms platform. The developed forms were based on existing international notification templates from the the perspective of NM services in operation applying Brazilian regulations.

Individual Monitoring of Internal Exposure for Nuclear Medicine Workers in NINMAS through In-Vitro Bioassay Techniques

Internal radiation monitoring of occupational radiation workers is essential for protecting them against the risks of incorporated radionuclides. More than 400 workers in Bangladesh are working with unsealed radioactive sources and most of them are employed at different nuclear facilities. Among the 18 Nuclear Medicine Centers in the country, the National Institute of Nuclear Medicine and Allied Science (NINMAS), Dhaka was selected for this study where workers get internal radiation exposure while processing and labeling of the liquid sources. The aim of this study was to estimate the activity concentration and committed effective doses from bioassay sample, namely urine samples of Nuclear Medicine (NM) workers due to handling of radioactive Iodine (131I), Technetium (99mTc) and Fluorine (F-18). Total 86 urine samples were collected from 17 occupational workers of NINMAS during the year 2017 and analyzed using High Purity Germanium (HPGe) detector. The radioactivity of 131I and (99mTc) was found 2.21±0.44 BqL-1 to 444 ± 39.91 BqL-1 and 5.53±1.12 BqL-1 to 603 ± 72.36 BqL-1 respectively. Due to low activity of the unsealed F-18 sources and for appropriate shielding, radioactivity of F-18 was found below the minimum detection level in the urine samples of the workers who handled it. The effective doses of occupational workers have also been calculated using the radioactivity concentration and the dose coefficients given in ICRP publication 78. The highest and lowest effective doses due to handling of the unsealed source of (99mTc) were 28.2 and 0.0258μSv for working with 780 and 36mCi of radionuclide respectively. On the other hand, the highest and lowest effective doses due to handling of 131I were 8.73and 0.045μSv, for working with 1425 and 55 mCi respectively. Both the doses are found to comply with ICRP annual dose limit of 20 mSv.
 Bangladesh J. Nuclear Med. 22(2): 125-129, Jul 2019

Preliminary Dose Assessment for Emergency Response Exercise Using Unsealed Radioactive Contamination.

A preliminary dose assessment for an emergency response exercise using unsealed radioactive sources was performed based on conservative calculation methods. The assessment was broken into four parts: activation, distribution, exercise participation, and post-exercise monitoring. The computer code MicroShield was used to determine external exposure from the source during and after distribution. Internal exposure via inhalation and ingestion was estimated by assuming fractional intakes of activity and converting to dose using annual limits on intake and dose coefficients. It was determined from the dose assessment that a radionuclide-dependent range of 37 MBq to 1.5 GBq can be used to achieve detectable dose rates during the exercise without exceeding assumed administrative dose limits. Of the identified radionuclides, Tc results in the lowest dose and is recommended from a radiological safety standpoint. However, the choice of which radionuclide and what activity to use for an exercise should be made based on budget and the logistics of the actual exercise.

Design and operation of a therapeutic unit with unsealed radioactive sources

A radioisotope therapeutic unit (RTU) for the treatment of patients with radiopharmaceuticals was designed and set in operation by the Ioannina University Hospital Medical Physics and Nuclear Medicine Departments. A number of parameters and procedures have been taken into account during the design stage to combine high quality medical services with minimum unjustified radiation exposures. Two pre-existing wards were modified to therapy / isolation wards by the addition of structural shielding made of concrete or/and iron and lead plates. Similar modifications were carried out in some of the remaining rooms of the RTU, such as the corresponding hot-lab and the storage-to-decay rooms. A network of GM detectors was installed for continuous monitoring of radiation levels at various locations. Among the first one hundred patients treated at the Unit, 80 had differentiated cancer and 14 had hyperthyroidism and were treated with 131I of activity ranging between 0.74 and 7.4 GBq. The maximum H*(10) rate at 1.0 m distance from the patient’s body was one of the criteria for patient release and was set on patient-specific terms. The adequacy of the RTU design and the employed operational policies were verified in practice. In conclusion, the RTU meets successfully the predicted needs.

Quality control to manage unsealed radioactive sources in nuclear medicine

Quality control to manage unsealed radioactive sources in nuclear medicine

Use of IAEA Radiation Dose Criteria to Assess the Need for Internal Radiation Dosimetry in Nuclear Medicine Practices

<p>The IAEA Safety Guide RS-G-1.2 recommends that occupational radiation monitoring should be implemented whenever it is likely that committed effective doses from annual intakes of radionuclides would exceed1mSv. This study presents the analysis of IAEA methodology for the evaluation of the need for the implementation of an internal monitoring program; considering that it should be carried out whenever the potential internal exposure of incorporation leads to a value of annual committed effective dose equal or higher than 1 m Sv. The IAEA criteria applied to commonly used radionuclides in nuclear medicine, taking into consideration usual manipulated unsealed radioactive sources and handling conditions. It is concluded that the handling of unsealed radioactive sources presents the risk of internal radiation exposure to the workers, requiring the implementation of an internal dosimetry program by the concerned Nuclear Medicine Institutes/Centers. </p><p>Bangladesh J. Nuclear Med. 20(1): 51-55, January 2017 </p>

Radionuclide Selection for Emergency Response Exercise at Disaster City® Using Unsealed Radioactive Contamination.

The Department of Nuclear Engineering at Texas A&M University currently supports exercises at Disaster City, a mock community used for emergency response training that features full-scale, collapsible structures designed to simulate various levels of disaster and wreckage. Emergency response exercises can be enhanced by using unsealed radioactive sources to simulate a more realistic response environment following an incident involving the dispersion of radioactive material. Limited exercises are performed worldwide using unsealed radioactive sources, and most of that information is not publicly available. This research compiles the publicly available information along with additional information acquired through discussion with experts and presents the process for selection of a short-lived radionuclide for use at Disaster City. The historically-used radionuclides were F, Tc, Br, and La. These radionuclides were considered for the Disaster City exercise, as well as other short-lived radionuclides commonly used or capable of being produced at Texas A&M. The selection process described in this paper identified seven radionuclides that could be used in an unsealed contamination exercise at Disaster City. Radiopharmaceuticals Tc and F are suitable and available for purchase from nearby vendors. In addition, the Texas A&M Nuclear Science Center TRIGA reactor could be used to produce Na, Mn, Cu, Br, and La via thermal neutron activation.

NCRP Program Area Committee 2: Operational Radiation Safety.

Program Area Committee 2 of the National Council on Radiation Protection and Measurements provides guidance for radiation safety in occupational settings in a variety of industries and activities. The Committee completed three reports in recent years covering recommendations for the development and administration of radiation safety programs for smaller educational institutions, requirements for self-assessment programs that improve radiation safety and identify and correct deficiencies, and a comprehensive process for effective investigation of radiological incidents. Ongoing work includes a report on sealed radioactive source controls and oversight of a report on radioactive nanomaterials focusing on gaps within current radiation safety programs. Future efforts may deal with operational radiation safety programs in fields such as the safe use of handheld and portable x-ray fluorescence analyzers, occupational airborne radioactive contamination, unsealed radioactive sources, or industrial accelerators.

MO‐A‐103‐01: Nuclear Medicine: Regulatory Guidelines and Computational Methods for Safe Release of Radioactive Patients

Radiation therapy using radioactive materials within the patient, i.e., permanently implanted sealed brachytherapy seeds and unsealed targeted radiopharmaceuticals, is routinely used to treat cancer patients. Radioactive patients may safely be released from radiation safety restrictions when the most exposed person is unlikely to receive more than 5 mSv (500 mrem) according to the United States Nuclear Regulatory Commission. NUREG 1556 Volume 9 Appendix U Revision 2 presents regulatory guidance that may be used to assure compliance with this limit. This risk‐based approach is a big step forward from the prior activity‐based release criteria. This session will introduce commonly used radiation therapies using internal sealed and unsealed radioactive sources and discuss the criteria and computational methods for the safe release of radioactive patients. Essential components of NRC Part 35 Medical Use of Byproduct Material will also be presented.Learning Objectives:1. Introduce commonly used radiation therapies involving internally administered radioactive materials2. Present NRC guidelines and perform the calculations in the regulatory guidance documents3. Understand the implications and limitation of the release criteria calculation

Internal Radiation Monitoring of Occupational Staff in Nuclear Medicine Facility

Unsealed radioactive sources used in Nuclear Medicine Centers, to diagnose and treat patients, pose significant risks of internal exposure to the occupational staff. This work intends to evaluate the potential risks of internal contamination of occupational staff in Nuclear Medicine facilities. 49 urine samples of 19 occupational staff working in the two busiest nuclear medicine centres, namely Institute of Nuclear Medicine and Ultrasound (INMU) and Centre of Nuclear Medicine and Ultrasound (CNMU) Dhaka, were collected to perform this study. The concentrations of 99mTc and 131I in urine samples were measured using a High Purity Germanium (HPGe) detector. The radioactivity of 99mTc and 131I were found to be 8.58±0.03 Bql-1 to 314±1.92 Bql-1 and from 6.47±0.03 Bql-1 to 283±0.27 Bql-1 respectively. The effective doses of occupational staff have also been calculated using the radioactivity concentration and the dose coefficients. Due to the highest (314 Bql-1) and the lowest (8.58Bql-1) concentration of 99mTc, the effective doses were 14.7 ?Sv and 0.402?Sv, on the other hand for the highest (283 Bql-1) and the lowest (6.47 Bql-1) concentration of 131I, the effective doses were 5.58 ?Sv and 0.12 ?Sv. These values are within limits, however to avoid inhalation and contamination of 131I and 99mTc proper working environment should be established with suitable ventilation system, fume hood, mask, etc. DOI: http://dx.doi.org/10.3329/bjmp.v5i1.14670 Bangladesh Journal of Medical Physics Vol.5 No.1 2012 63-70

Principles of Nuclear Medicine Imaging: Planar, SPECT, PET, Multi-modality, and Autoradiography Systems

The underlying principles of nuclear medicine imaging involve the use of unsealed sources of radioactivity in the form of radiopharmaceuticals. The ionizing radiations that accompany the decay of the administered radioactivity can be quantitatively detected, measured, and imaged in vivo with instruments such as gamma cameras. This paper reviews the design and operating principles, as well as the capabilities and limitations, of instruments used clinically and preclinically for in vivo radionuclide imaging. These include gamma cameras, single-photon emission computed tomography (SPECT) scanners, and positron emission tomography (PET) scanners. The technical basis of autoradiography is reviewed as well.

Molecular radiotherapy — the radionuclide raffle?

Molecular radiotherapy — the radionuclide raffle?

Syllabus for postgraduate specialisation in Nuclear Medicine

Nuclear Medicine (NM) became an independent medical specialty in the European Directives in 1988. The minimum duration of the postgraduate specialized training in the European Union is 4 years, but may be extended beyond this period according to the requirements of training in other clinical disciplines. Candidates for specialized training should have a good general background in internal medicine. More detailed knowledge has to be acquired of those conditions which may need to be investigated or treated by NM techniques, as well as of some complementary methods as far as they relate to NM procedures. Training in basic sciences is required, such as pharmacokinetics, radiochemistry, instrumentation, computer science and quality control. The quality of training has to be objectively assessed, using final examination on a national basis covering basic sciences and clinical skills, after satisfactory completion of a minimum number of courses and/or workshops and a formally organized and controlled practical training. Each training programme should contain a standard against which the progress of the trainee can be assessed for each element of the syllabus. The assessment may take the form of an interview, a written paper, an essay, a set of multiple-choice questions, or an oral examination of displayed images of various NM techniques in clinical practice. Continuous assessment is another alternative. Each end of year assessment should carry a score that indicates how the candidate has progressed against the set target. Successful trainees are awarded with a final certificate, degree or diploma that is recognized by the government, local health authority and hospital as an assurance of specialist competence in NM. The clinical training of physicians specializing in NM should include: 1) a minimal theoretical foundation of the general principles of NM with active participation in clinical presentations, seminars and meetings and 2) in vivo diagnostic procedures. Personal responsibility (including indication, performance and interpretation) must be taken for at least 3.000 in vivo NM diagnostic procedures, with a broad-spectrum of the most currently used procedures. The list of the procedures published in the syllabus will be subject to revision. It is recommended that a period of training be spent away from the main department in at least one other recognized centre. In addition the training should cover therapy with unsealed radioactive sources. The trainee must have taken part in a sufficient number of Eur J Nucl Med Mol Imaging DOI 10.1007/s00259-006-0334-9

Traceability in nuclear medicine

Accurate, reproducible measurement of radioactivity in nuclear medicine applications is vital to ensure the safety and effectiveness of disease diagnosis and treatment using unsealed radioactive sources. The need to maintain a high degree of confidence in those measurements requires that they be carried out so as to be traceable to national and international standards. In addition, measurement traceability for radioactivity in medicine helps ensure international consistency in measurement at all levels of practice (national measurement laboratories, research institutions, isotope producers, radiopharmaceutical manufacturers and clinics). This paper explores the importance of radioactivity measurement in nuclear medicine and demonstrates how traceability can be extended from international standards to the quantity of the drug administered to the patient.

EXTREMITY DOSIMETRY FOR RADIATION WORKERS HANDLING UNSEALED RADIONUCLIDES IN NUCLEAR MEDICINE DEPARTMENTS IN INDIA

In India, for the past five decades, whole body radiation dose of radiation workers has been monitored by means of film and thermoluminescent dosimeter (TLD) badges worn on the body. However, there are no provision/regulatory requirements to monitor doses received at the extremities, i.e., to fingers. Finger dose monitoring is essential for controlling the extremity dose limits for occupational personnel handling unsealed radioactive sources. In order to estimate the doses received in various types of procedures using unsealed sources, finger dose monitoring was carried out in 54 major institutions in the country using a specially designed plastic finger ring embedded with a TLD. The maximum finger dose of occupational workers involved in handling Tc in such activities as extraction and radiopharmacy work is 0.35 mSv GBq; during injection of radiopharmaceuticals and scintigraphy, the doses were observed to be 1 and 0.95 mSv GBq, respectively. Similarly, while handling F-FDG, the maximum doses received during dispensing, injection, and scintigraphy were 0.098, 0.324, and 0.56 mSv GBq, respectively. The maximum radiation dose received during Re/Re balloon angioplasty and while handling Sm was 3.92 and 6.5 mSv GBq, respectively. All the doses recorded were well within the prescribed limit. However, monitoring of these doses periodically would help in compiling the feedback regarding the work practices followed in institutions handling radioisotopes in the country and would also help in maintaining a record of safe work procedures while handling radioisotopes.

Design of radiolabelled ligands for the imaging and treatment of cancer

The specialised medical field of Nuclear Medicine is concerned with the use of unsealed sources of radioactivity either to diagnose or treat a range of diseases. In this regard it can be distinguished from the field of Radiotherapy which uses sealed radioactive sources for treatment. The range of diseases in which Nuclear Medicine plays a role is wide and includes, among others, the fields of microbiology, endocrinology, neurology, oncology and cardiovascular medicine. However, cancer probably represents the most important and growing area of application for this modality. Nuclear Medicine employs radiopharmaceuticals. These are radiolabelled ligands that have the ability to interact with molecular targets that are relevant in the aetiology or treatment of cancer and in many respects Nuclear Medicine can be considered the archetype for the application of 'Molecular Medicine'. An example of a Nuclear Medicine Positron Emission Tomography (PET) scan is shown in Fig. 2. There is great interest in developing new radioligands that allow us to image the expression of the ever increasing range of biological pathways being discovered in the post-genomic area. Designing effective radiopharmaceuticals, however, requires an understanding of a number of radiopharmaceutical sciences including aspects of chemistry, physics, cell and molecular biology, and physiology.