Hand exposure in diagnostic nuclear medicine with 18F- and 99mTc-labelled radiopharmaceuticals - Results of the ORAMED project

Development of the occupational exposure during the production and application of radiopharmaceuticals in Germany

An increasing number of radiopharmaceuticals and proteins are available for diagnosing and treating various diseases. The demand for existing and newly developed pharmaceutical radionuclides and proteins is steadily increasing. The radiation exposure levels of workers in the radiopharmaceutical industry and nuclear medicine field are closely monitored, specifically their effective dose and equivalent dose, leading to the question, of whether the dawn of radiopharmaceuticals affects the occupational exposure level. This development is analyzed and evaluated with data from the German National Dose Register. Data shows that the effective dose in the work categories production and distribution of radioisotopes as well as nuclear medicine slightly decreased from 1997 to 2021. Over the same period, the hand equivalent dose in nuclear medicine increases steadily, with no discernible trend in production and distribution of radioisotopes. Over the past few decades, intentional efforts and measures have been taken to ensure radiation protection. Instruments for monitoring and dose reduction must be continuously applied. Given the low effective dose, the focus in future shall be on dose reduction following theaslowasreasonablyachievable principle. The development of the hand equivalent dose should be carefully observed in the upcoming years.

Radiation exposure assessment of nuclear medicine staff administering [177Lu]Lu-DOTA-TATE with active and passive dosimetry

BACKGROUND

The use of lutetium-177 (177Lu)-based radiopharmaceuticals in peptide receptor nuclear therapy is increasing, but so is the number of nuclear medicine workers exposed to higher levels of radiation. In recent years, [177Lu]Lu-DOTA-TATE has begun to be widely used for the treatment of neuroendocrine tumours. However, there are few studies evaluating the occupational radiation exposure during its administration, and there are still some challenges that can result in higher doses to the staff, such as a lack of trained personnel or fully standardised procedures. In response, this study aims to provide a comprehensive analysis of occupational doses to the staff involved in the administration of [177Lu]Lu-DOTA-TATE.

RESULTS

A total of 32 administrations of [177Lu]Lu-DOTA-TATE (7.4 GBq/session) carried out by a physician and a nurse, were studied. In total, two physicians and four nurses were independently monitored with cumulative (passive) and/or real-time (active) dosemeters. Extremity, eye lens and whole-body doses were evaluated in terms of the dosimetric quantities Hp(0.07), Hp(3) and Hp(10), respectively. It was obtained that lead aprons reduced dose rates and whole-body doses by 71% and 69% for the physicians, respectively, and by 56% and 68% for the nurses. On average, normalised Hp(10) values of 0.65 ± 0.18 µSv/GBq were obtained with active dosimetry, which is generally consistent with passive dosemeters. For physicians, the median of the maximum normalised Hp(0.07) values was 41.5 µSv/GBq on the non-dominant hand and 45.2 µSv/GBq on the dominant hand. For nurses 15.4 µSv/GBq on the non-dominant and 13.9 µSv/GBq on the dominant hand. The ratio or correction factor between the maximum dose measured on the hand and the dose measured on the base of the middle/ring finger of the non-dominant hand resulted in a factor of 5/6 for the physicians and 3/4 for the nurses. Finally, maximum normalised Hp(3) doses resulted in 2.02 µSv/GBq for physicians and 1.76 µSv/GBq for nurses.

CONCLUSIONS

If appropriate safety measures are taken, the administration of [177Lu]Lu-DOTA-TATE is a safe procedure for workers. However, regular monitoring is recommended to ensure that the annual dose limits are not exceeded.

Personal dose equivalent Hp(0.07) during 68Ga-DOTA-TATE production procedures

This work presents the exposure of hands of the personnel of a nuclear medicine department who prepare and administer ⁶⁸Ga-DOTA-TATE. Dosimetry measurements were performed during three 1-week sessions, for nine production procedures. A total of 360 measurements were made by using high-sensitivity MCP-N thermoluminescent detectors. Annealed detectors were and vacuum-packed in foil and then placed on each fingertip of both hands of five radiochemists and four nurses (one detector for one fingertip). The greatest exposure to ionizing radiation was found on the non-dominant left hand of radiochemists and nurses. A maximum H_p(0.07)/A value of 49.36 ± 4.95 mSv/GBq was registered for radiochemists during the ⁶⁸ Ga-DOTA-DATE activity dispensing procedure. For nurses performing the radiopharmaceutical injection procedure, a corresponding maximum value of 1.28 ± 0.13 mSv/GBq was measured, while the mean value for all the nurses was 0.38 mSv/GBq. The dispensing procedure accounted for approximately 60% of the total exposure of radiochemists' fingertips. Based on the results obtained it is recommended that a ring dosimeter should be routinely placed on the middle finger of the non-dominant hand of radiochemists and nurses. Furthermore, it is proposed to systematically train workers in handling open sources of ionizing radiation, with the aim of reducing the required handling time.

Occupational radiation exposure assessment during the management of [68Ga]Ga-DOTA-TOC

Background

Since it was first approved in Europe in 2016, the gallium-68 (⁶⁸Ga) radiopharmaceutical [⁶⁸Ga]Ga-DOTA-TOC has been widely used for imaging of somatostatin receptor (SSTR) positive tumours using positron emission tomography–computed tomography (PET/CT). Significant patient benefits have been reported, so its use is rapidly increasing. However, few studies have been published regarding occupational doses to nuclear medicine personnel handling this radiopharmaceutical, despite its manual usage at low distances from the skin and the beta-emission decay scheme, which may result in an increased absorbed dose to their hands. In this context, this study aims to analyse the occupational exposure during the administration of [⁶⁸Ga]Ga-DOTA-TOC for PET/CT imaging. For this purpose, extremity, eye lens and whole-body dosimetry in terms of Hp(0.07), Hp(3) and Hp(10), respectively, was conducted on six workers with both thermoluminescent dosimeters, and personal electronic dosimeters.

Results

The non-dominant hand is more exposed to radiation than the dominant hand, with the thumb and the index fingertip being the most exposed sites on this hand. Qualitative analysis showed that when no shielding is used during injection, doses increase significantly more in the dominant than in the non-dominant hand, so the use of shielding is strongly recommended. While wrist dosimeters may significantly underestimate doses to the hands, placing a ring dosimeter at the base of the ring or middle finger of the non-dominant hand may give a valuable estimation of maximum doses to the hands if at least a correction factor of 5 is applied. Personal equivalent doses for the eyes did not result in measurable values (i.e., above the lowest detection limit) for almost all workers. The extrapolated annual dose estimations showed that there is compliance with the annual dose limits during management of [⁶⁸Ga]Ga-DOTA-TOC for diagnostics with PET in the hospital included in this study.

Conclusions

Imaging with [⁶⁸Ga]Ga-DOTA-TOC is a safe process for the workers performing the administration of the radiopharmaceutical, including intravenous injection to the patient and the pre- and post-activity control, as it is highly unlikely that annual dose limits will be exceeded if good working practices and shielding are used.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40658-022-00505-8.

Radiation exposure to extremities in medical applications and its implications for the radiation protection of workers in the Philippines

In medical applications, non-homogeneous radiation exposure conditions may be encountered and whole-body monitoring alone may not be an adequate assessment of doses received by workers. This paper investigated the exposure to extremities in medical applications in the Philippines in terms of personal dose equivalent H_p(0.07). Profiles of monitored workers, dose levels, implications on optimization of occupational exposures, and factors affecting the extremity monitoring implementation were studied. The results show that <3% of workers are monitored for extremities, and there is no monitoring of eye lens dose. There is no extremity monitoring in diagnostic radiology, particularly interventional radiology. Dose levels to extremities were higher and more varied than whole-body doses. In nuclear medicine, the median annual extremity dose is 1.2 mSv, the interquartile range (IQR) is 7.6 mSv (Q1 = 0.5 mSv, Q3 = 8.1 mSv), and the maximum dose is 35 mSv. These median and IQR dose values are four and eight times higher, respectively, compared to the whole-body dose. In radiopharmaceutical distribution, the extremity median annual dose is five times higher than the whole-body dose, and the IQR value is 12 times higher where IQR is 12.1 mSv (Q1 = 0.1 mSv, Q3 = 12.2 mSv). Most notable is in cyclotron operations where <40% of workers were monitored on their extremities; however, the median dose is 100 times higher than the whole-body dose, with a maximum dose of 148 mSv. The results imply that there may be an underassessment of occupational exposure of workers in medical applications. As monitoring results are used for the establishment of a radiation protection program, lack of consideration of extremity doses can lead to inadequate measures in the optimization of worker protection. This study thus shows the need to enhance the implementation of extremity and eye lens dose monitoring in the Philippines to further strengthen the radiation protection of workers in medical applications.

Assessment of extremity exposure to technologists working manually with99mTc-labelled radiopharmaceuticals and with an automatic injection system for18F-FDG

The hands of nuclear medicine (NM) personnel involved in radiopharmaceutical preparation and administration can receive significant radiation doses. The dose distribution across the hand is nonuniform and the Hp(0.07) doses obtained by an individual passive ring dosimeter do not always present a real situation. The aim of this study was to assess the extremity exposure of NM workers working with^99mTc-labelled radiopharmaceuticals and with an automatic IRIDE (COMECER, Italy)¹⁸F-FDG injection system. Hp(0.07) doses were measured using calibrated thermoluminescent dosimeters-100 (TLD-100) and were read by a RIALTO TLD (NE Technology) reader. It was found that the most exposed parts of the hand during work with¹⁸F and^99mTc radionuclides are the fingertips of the thumb, index finger and middle finger. The maximum fingertip doses were 1.3-2.4 times higher compared with the doses from the typical monitoring position (base of the middle finger of the dominant hand). When working with^99mTc, the average hand doses were relatively high, i.e. 0.17 ± 0.04 and 0.37 ± 0.13 mSv Gbq^-1for the left and the right hand, respectively, during preparation, and 58 ± 20 and 53 ± 13µSv GBq^-1for the left and the right hand, respectively, during administration of^99mTc labelled radiopharmaceuticals. Meanwhile, the lowest doses were found for hands during administration of¹⁸F-FDG (average hand dose 28 ± 13µSv GBq^-1for the left hand and 28 ± 7µSv GBq^-1for the right hand), which shows the advantages of automated injection/infusion systems, thus implementation of automatic infusion/injection in hospitals could be an expedient way to optimize Hp(0.07) doses to NM workers.

Radiation Safety and Accidental Radiation Exposures in Nuclear Medicine

Medical radiation accidents and unintended events may lead to accidental or unintended medical exposure of patients and exposure of staff or the public. Most unintended exposures in nuclear medicine will lead to a small increase in risk; nevertheless, these require investigation and a clinical and dosimetric assessment. Nuclear medicine staff are exposed to radiation emitted directly by radiopharmaceuticals and by patients after administration of radiopharmaceuticals. This is particularly relevant in PET, due to the penetrating 511 keV γ-rays. Dose constraints should be set for planning the exposure of individuals. Staff body doses of 1-25 µSv/GBq are reported for PET imaging, the largest component being from the injection. The preparation and administration of radiopharmaceuticals can lead to high doses to the hands, challenging dose limits for radionuclides such as ⁹⁰Y and even ¹⁸F. The risks of contamination can be minimized by basic precautions, such as carrying out manipulations in purpose-built facilities, wearing protective clothing, especially gloves, and removing contaminated gloves or any skin contamination as quickly as possible. Airborne contamination is a potential problem when handling radioisotopes of iodine or administering radioaerosols. Manipulating radiopharmaceuticals in laminar air flow cabinets, and appropriate premises ventilation are necessary to improve safety levels. Ensuring patient safety and minimizing the risk of incidents require efficient overall quality management. Critical aspects include: the booking process, particularly if qualified medical supervision is not present; administration of radiopharmaceuticals to patients, with the risk of misadministration or extravasation; management of patients' data and images by information technology systems, considering the possibility of misalignment between patient personal data and clinical information. Prevention of possible mistakes in patient identification or in the management of patients with similar names requires particular attention. Appropriate management of pregnant or breast-feeding patients is another important aspect of radiation safety. In radiopharmacy activities, strict quality assurance should be implemented at all operational levels, in addition to adherence to national and international regulations and guidelines. This includes not only administrative aspects, like checking the request/prescription, patient's data and the details of the requested procedure, but also quantitative tests according to national/international pharmacopoeias, and measuring the dispensed activity with a calibrated activity meter prior to administration. In therapy with radionuclides, skin tissue reactions can occur following extravasation, which can result in localized doses of tens of Grays. Other relevant incidents include confusion of products for patients administered at the same time or malfunction of administration devices. Furthermore, errors in internal radiation dosimetry calculations for treatment planning may lead to under or over-treatment. According to literature, proper instructions are fundamental to keep effective dose to caregivers and family members after patient discharge below the Dose constraints. The IAEA Basic Safety Standards require measures to minimize the likelihood of any unintended or accidental medical exposures and reporting any radiation incident. The relative complexity of nuclear medicine practice presents many possibilities for errors. It is therefore important that all activities are performed according to well established procedures, and that all actions are supported by regular quality assurance/QC procedures.

Review of extremity dosimetry in nuclear medicine

The exposure of the fingers is one of the major radiation protection concerns in nuclear medicine (NM). The purpose of this paper is to provide an overview of the exposure, dosimetry and protection of the extremities in NM. A wide range of reported finger doses were found in the literature. Historically, the highest finger doses are found at the fingertip in the preparation and dispensing of¹⁸F for diagnostic procedures and⁹⁰Y for therapeutic procedures. Doses can be significantly reduced by following recommendations on source shielding, increasing distance and training. Additionally, important trends contributing to a lower dose to the fingers are the use of automated procedures (especially for positron emission tomography (PET)) and the use of prefilled syringes. On the other hand, the workload of PET procedures has substantially increased during the last ten years. In many cases, the accuracy of dose assessment is limited by the location of the dosimeter at the base of the finger and the maximum dose at the fingertip is underestimated (typical dose ratios between 1.4 and 7). It should also be noted that not all dosimeters are sensitive to low-energy beta particles and there is a risk for underestimation of the finger dose when the detector or its filter is too thick. While substantial information has been published on the most common procedures (using^99mTc,¹⁸F and⁹⁰Y), less information is available for more recent applications, such as the use of⁶⁸Ga for PET imaging. Also, there is a need for continuous awareness with respect to contamination of the fingers, as this factor can contribute substantially to the finger dose.

Need for harmonisation of extremity dose monitoring in nuclear medicine: results of a survey amongst national dose registries in Europe

Staff handling radiopharmaceuticals in nuclear medicine (NM) may receive significant extremity doses. Over the last decade in particular there has been an increase in NM procedures and new radiopharmaceuticals have been introduced. However, literature provides limited recent data on the exposure of the extremities. In addition, proper assessment of the equivalent dose to the skin can be difficult when applied to the fingertips. In order to gain insight in the actual exposure and to find out how European countries are dealing with monitoring of the extremities, a survey was performed amongst European regulatory authorities. The questions covered general aspects of the national dose registries (NDRs), the measured extremity doses and the practice of the monitoring of workers. The survey shows that extremity dosimetry is performed for about 25%-50% of the monitored workers in NM. Also, the recorded extremity doses in the NDRs are low (mean values 5-29 mSv yr^-1) compared to the dose limit. Despite the recommendations that have been published in the last 10 years, few countries provide guidance on the wearing position of extremity dosemeters and the correction factor to estimate the maximum equivalent skin dose from the measured dose. This may lead to an underestimation of the maximum skin dose. Thermoluminescence ring dosemeters are widely used, but wrist dosemeters are also very common, even though the correlation of the measurement with the maximum skin dose is worse than for ring dosemeters. Furthermore, not all countries had a central registration of the extremity dose at the time the survey was performed.

ANALYSIS OF HAND EXPOSURE AMONG NUCLEAR MEDICINE TECHNOLOGISTS IN SAUDI ARABIA

The increase in the amount of radioactive materials administered to patients as well as the number of procedures performed has focused attention on the issue of radiation exposure to the hands of workers in nuclear medicine departments worldwide. The study aims to estimate the equivalent doses to the hands of individuals in nuclear medicine departments in Saudi. A cross-sectional analysis was conducted for 404 annual dose records in 16 nuclear medicine departments from 2016 to 2019. The monitoring of individual doses to the hands was performed using a Harshaw ring dosemeters. During the study period, the average annual equivalent doses per handled activity ranged from 0.21 to 0.41 μSv/GBq. The estimated annual activities of radiopharmaceuticals ranged from 2 to 930 MBq per exam. The hand dose averaged over the 4-year study period was determined to be 1.81 ± 0.25 mSv. The collective annual hand dose increased by 265% from 2016 to 2019.

Ambient and personnel occupational dose assessment in a Hospital's PET/CT center

This study used thermoluminescent dosimeters (TLDs) to measure cumulative radiation doses in a PET/CT center. It covered 18 areas and four personnel groups. Because the isolated lead shielding separated the patients from the nurses, wearing protective clothing when injecting radiopharmaceuticals was unnecessary. Fingertip doses of the dispensing and nurse groups were below the occupational limit. Current radiopharmaceutical transportation and injection operations in this PET/CT center provide considerable radiation protection to medical personnel.

Using Monte Carlo methods for Hp(0.07) values assessment during the handling of 18F-FDG

The dose limit for the skin of the hand is typically converted to a surface of 1 cm², which means that one needs to measure point doses in different places on the hand. However, the commonly used method of measuring doses on the hand, i.e., using a dosimetric ring including one or several thermoluminescent detectors worn at the base of a finger, is not adequate for manual procedures such as labeling or radiopharmaceutical injection. Consequently, the purpose of this study was to create and conduct a series of computer simulations that, by recreating the actual working conditions, would provide information on the values of ionizing radiation doses received by the most exposed parts of the hands of employees of radiopharmaceutical production facilities, as well as those of nurses during the injection of radiopharmaceuticals. The simulations were carried out using Monte Carlo radiation transport calculations. The H_p(0.07) personal dose equivalent values obtained for the fingertips of the index and middle fingers of nursing staff and chemists were within the range limited by the minimum and maximum H_p(0.07) values obtained as a result of dosimetric measurements carried out in diagnostic and production centers. Only in the case of the nurse's fingertip, the simulated value of H_p(0.07 slightly exceeded the measured maximum H_p(0.07) value. The comparison of measured and simulated dose values showed that the largest differences in H_p(0.07) values occurred at the thumb tip, and for ring finger and middle finger of some of the nurses investigated.

A new mobile self-dispensing and administering system for 18F-FDG: evaluation of operator dose reduction

PURPOSE

Recently new mobile systems for dispensing positron emitters have been produced, designed to guarantee dispensing cycles in an aseptic environment. The aim of the present work was to assess the advantage of one of these systems in radiation protection of operators in clinical settings.

METHODS

Recently, in our centre the new self-dispensing system named KARL₁₀₀ by Tema Sinergie was adopted for ¹⁸F-FDG radiopharmaceuticals. The system is associated with an automatic Rad-inject infuser. The system that was previously used was a fixed isolator NMC DSI (Tema Sinergie), equipped with a μDDS-An activity fractioning system, together with a pneumatic post for the syringe delivery. The dosimetric evaluations on both systems were carried out through environmental measurements with an ionisation chamber and with the use of personal dosimeters.

RESULTS

The operations of preparation and administration of ¹⁸F-FDG dose to the patient, with the use of Karl₁₀₀ + RadInject, involve exposures much lower than those obtained by the fixed isolator. The average body exposure of the technician was reduced by 31%, and for the physician by 77%. On the extremities, the equivalent dose to the hands of the technician was reduced by 78%, and for the physician by 96%. Also the additional dosimeters worn by the technician confirmed the estimated environmental assessments.

CONCLUSIONS

The exposures of the working personnel were significantly reduced with the introduction of the new KARL₁₀₀ system.

THE STRUCTURE OF Hp(0.07) VALUES OBTAINED BY THE NUCLEAR MEDICINE PERSONNEL DURING 18F-FDG PRODUCTION AND INJECTION

The production of 18F-FDG is a multi-stage process, which includes not only obtaining the marker and labelling the radiopharmaceutical but also carrying out the quality control of the obtained compound. The staff can be exposed to ionizing radiation at any stage of production. This article presents the results of hands exposure of staff members employed in a facility, where 18F-FDG is produced and injected into patients. High-sensitivity thermoluminescent detectors (MCP-N) were used for measurements. The measurements were conducted with regard to the occupational structure the employees and the performed procedures. The obtained results showed that the highest risk of radiation exposure for personnel was associated with the quality control of the radiopharmaceutical. The daily doses registered by MCP-N detectors on fingertips reached 4.5 mSv, which may result in exceeding the annual radiation limit of 500 mSv.

Wrist dosimeter in nuclear medicine - An alternative for the ring dosimeter?

PURPOSE

Individual dosimetry is undoubtedly one of the best methods of assessing the exposure of personnel to ionizing radiation, however in case of nuclear medicine, the method applied to measure the dose does not always present a picture of the worker's actual exposure. The highly non-homogeneous dose distribution on the hand means that the ring dosimeter, routinely used to measure the Hp(0.07), provides only approximate dose values received by fingertips, the body part most exposed to ionizing radiation. This paper is an attempt to answer the question whether the wrist dosimeter used as a replacement for the ring dosimeter is able to provide information on doses for the most exposed fragments of the hand of an employee during handling procedures with the use of radiopharmaceuticals.

MATERIALS

Throughout measurements performed in five nuclear medicine facilities, high-sensitivity thermoluminescent detectors were used.

RESULTS

Correction coefficients have been determined, which constitute an amendment to be made to move from the dose recorded by the wrist dosimeter to the doses received by the most exposed hand fragments. The fingertips received on average 25 times higher doses, compared to the values recorded by the wrist dosimeter.

CONCLUSIONS

A wrist dosimeter can be used to measure the Hp(0.07) in nuclear medicine, including as a gauge of the most exposed parts of the hand - the fingertips. However, the applicability of correction coefficients makes it necessary to ensure a stable position of the wrist dosimeter during routine procedures.

The effect of work system on the hand exposure of workers in 18F-FDG production centres

The production of the 18F isotope-the marker of deoxyglucose (18F-FDG)-the radiopharmaceutical most commonly used in the oncological diagnostic technique of positron emission tomography, requires a cyclotron device. At present, there are nine facilities working in Poland that are equipped with cyclotrons used for producing the short-lived isotopes. The aim of the paper is to determine the hand exposure of workers employed in the two 18F-FDG production centres taking in to account the production procedures and work system in those facilities. Measurements, which included all professional workers exposed to ionizing radiation that were employed in two facilities, were performed by using high-sensitivity thermoluminescent detectors during the routine activities of the personnel. The work system used at the production centre has an impact on the level of the recorded doses. Among the production procedures performed by the staff, the highest ionizing radiation doses have been received by the staff during the 18F-FDG quality control. The maximum estimated annual Hp(0.07) for chemists from the quality control department can exceed the annual skin limit dose (500 mSv). The source of lowest doses on the hands are the cyclotron operating procedure and the 18F-FDG production, provided that these procedures can't be combined with other production procedures.

Evaluation of Radiation Exposure to Staff and Environment Dose from [18F]-FDG in PET/CT and Cyclotron Center using Thermoluminescent Dosimetry

BACKGROUND

PET/CT imaging using [18F]-FDG is utilized in clinical oncology for tumor detecting, staging and responding to therapy procedures. Essential consideration must be taken for radiation staff due to high gamma radiation in PET/CT and cyclotron center. The aim of this study was to assess the staff exposure regarding whole body and organ dose and to evaluate environment dose in PET/CT and cyclotron center.

MATERIALS AND METHODS

80 patients participated in this study. Thermoluminescence, electronic personal dosimeter and Geiger-Muller dosimeter were also utilized for measurement purpose.

RESULTS

The mean annual equivalent organ dose for scanning operator with regard to lens of eyes, thyroid, breast and finger according to mean±SD value, were 0.262±0.044, 0.256±0.046, 0.257±0.040 and 0.316±0.118, respectively. The maximum and minimum estimated annual whole body doses were observed for injector and the chemist group with values of (3.98±0.021) mSv/yr and (1.64±0.014) mSv/yr, respectively. The observed dose rates were 5.67 µSv/h in uptake room at the distance of 0.5 meter from the patient whereas the value 4.94 and 3.08 µSv/h were recorded close to patient's head in PET/CT room and 3.5 meter from the reception desk.

CONCLUSION

In this study, the injector staff and scanning operator received the first high level and second high level of radiation. This study confirmed that low levels of radiation dose were received by all radiation staff during PET/CT procedure using 18F-FDG due to efficient shielding and using trained radiation staff in PET/CT and cyclotron center of Masih Daneshvari hospital.

Hand exposure of workers in 18F-FDG production centre

¹⁸F-FDG is the most popular radiopharmaceutical used, among others, in oncological diagnostics by PET technique. The production of ¹⁸F-FDG is a multistep process that begins by obtaining the radioisotope ¹⁸F, and subsequently labelling the radiopharmaceutical, as well as quality control of the resulting compound. In each of these stages, the employee has contact with ionizing radiation. The production of ¹⁸F requires the use of a cyclotron device. Currently in Poland, there are 9 centres equipped with a cyclotron for the production of positron-emitting radioisotopes. The monitoring of the occupational exposure to ionizing radiation in these centres is performed by measuring the effective and equivalent dose. Neither of these forms fully reflects the exposure of the worker, which is largely associated with handling procedures. The ¹⁸F radiopharmaceutical preparation process runs automatically, which partially reduces the level of staff exposure, but the quality control step of the pharmaceutical requires handling procedures with a vial containing an activity of a radiopharmaceutical ranging from 4 GBq to 10 GBq. In the work presented, measurements were performed of hand exposure, in units the equivalent dose (H _p (0.07)), of the staff who are involved in the procedures of ¹⁸F-FDG production in one of the national production centres. The high-sensitivity thermoluminescent detectors (MCP) were used to measure the doses. The measurements were performed for three groups of workers: operators of the cyclotron, those who produce the ¹⁸F-FDG, and quality control staff. Detectors were placed on the fingertips of the left and right hand, as well as in a standard ring dosemeter location. The results indicate that the largest exposure happens among the group of workers involved in the radiopharmaceutical's quality control. The doses recorded by the MCP detectors placed on the fingertips during one working day reach a value up to 2 mSv, which may result in exceeding the annual dose limit (500 mSv).

ASSESSMENT OF THE LOCAL EXPOSURE OF SKIN ON HANDS OF NUCLEAR MEDICINE WORKERS HANDLING 18F-LABELLED RADIOPHARMACEUTICALS: PRELIMINARY CZECH STUDY

The article summarises some preliminary results of the assessment of the exposure of hands of workers manipulating ¹⁸F-labelled radiopharmaceuticals based on personal monitoring at two nuclear medicine clinics in the Czech Republic. The measurements were carried out using special thermoluminescence dosemeters the readings of which could be interpreted in terms of the personal dose equivalent H_p(0.07) approximating the equivalent dose to the skin at various locations on the surface of both hands. The results have shown that out of 21 workers monitored, ∼43 % (preparation and applications of radiopharmaceuticals) may reach an exposure equal to three-tenth of the annual dose limit to the skin. At the same time, it can also be concluded that in ∼10 % cases of workers, the relevant dose limit may be exceeded.

EYE LENS DOSES IN NUCLEAR MEDICINE: A MULTICENTRIC STUDY IN BELGIUM AND POLAND

This study aimed to investigate the level of the eye lens (EL) doses in nuclear medicine in the light of the new International Commission on Radiological Protection limit. In 7 Belgian and 1 Polish hospitals, 45 staff members were monitored for EL (Hp(3)) and whole-body (WB) (Hp(10)) doses using dedicated dosemeters. Weekly measurements were carried out and used to estimate annual doses. Mostly diagnostic procedures involving radionuclides such as (99m)Tc and (18)F were monitored; measurements were also performed for therapeutic procedures. The cumulative doses showed important variation across the participants. The weekly EL and WB doses ranged from 0.02 to 0.27 and 0.03 to 0.17 mSv, respectively; the annual EL and WB doses ranged from 0.6 to 9.3 and 0.9 to 8.0 mSv, respectively. Some correlation was found between the EL and the WB doses. No significant correlation with the manipulated activities was found.

HAND DOSE EVALUATION OF OCCUPATIONALLY EXPOSED STAFF IN NUCLEAR MEDICINE

Manipulation of unsealed radiation sources in nuclear medicine (NM) departments involves non-uniform exposure to staff and high skin doses to the upper extremities from direct and scattered radiations. Conducted studies have shown that the annual dose limits could be exceeded and the continuous dose monitoring of NM worker's hands is needed. The aim of this article is to show results of hand dose monitoring in terms of operational quantity Hp(0.07) for occupationally exposed NM workers to beta and gamma radiations in the largest NM centre in Serbia. Dose assessment was done by means of thermoluminescent ring dosemeters DXT-RAD (LiF:Mg,Ti). Monthly and annual doses were evaluated for a 5-y period (2010-14). Monitored NM staff was categorised according to the type of work, as nurses, radiographers, laboratory technicians and radiochemists. Performed evaluation showed that annual hand doses were within the annual limit for all staff categories, but further optimisation of working practice is needed.

Strategies for assessment of doses to the tips of the fingers in nuclear medicine

Staff manipulating radiopharmaceuticals in radiopharmacies and nuclear medicine departments can receive significant radiation doses to the tips of their fingers. However, dosemeters for monitoring the fingers are frequently attached to a ring worn at the base of the finger and the doses recorded are significantly lower. Therefore a correction factor is required to estimate the dose to the finger tip from that recorded by a ring dosemeter. A survey of practices in UK nuclear medicine departments has been undertaken via a questionnaire, results of studies in the literature reporting ratios of doses to the tip and base of the finger reviewed, and patterns of finger exposure studied using an electronic dosemeter. The survey indicates that UK staff use vial and syringe shields for the majority of manipulations. Ratios between doses to the tip and base of the index finger reported in the literature vary between 2 and 6. Higher ratios appear to be associated with poor protection practices including not using syringe shields and use of a finger to support a syringe needle. Staff are recommended to wear dosemeters on the palmar side of the index finger of each hand. Dosemeters worn at the finger tips are ideal, but doses to the tips can be estimated from ring dosemeters worn on the index fingers, and factors that can be used for this are proposed. For staff who always use vial and syringe shields and never touch the syringe needle or vial a factor of 3 is appropriate. For staff who mostly use syringe shields and may occasionally support a needle during an injection, a factor of 4 can be used, while for others a factor of 6 should be applied.

Effect of dosimeter's position on occupational radiation extremity dose measurement for nuclear medicine workers during (18)F-FDG preparation for PET/CT

Background

The recent spread of positron emission tomography-computed tomography (PET/CT) poses extremity dosimetry challenges. The question arose whether the radiation dose measured by the ring thermoluminescent dosimeter usually worn on the proximal phalanx (P1) of the index finger measures doses that are representative of the true doses received by the upper extremities of the operators. A prospective individual dosimetry study was performed in which the personal equivalent dose Hp (0.07) received during a specific 2-[¹⁸F]fluoro-2-deoxy-d-glucose (¹⁸F-FDG) manual dose-dispensing procedure was measured in a paired design by two operational personal electronic dosimeters fitted on the palm side of the index finger, namely in the P1 and distal phalanx (P3) positions. The study participants were ten nuclear medicine technologists working in two nuclear medicine departments. The personal equivalent radiation doses received by the palm side of the proximal phalanx of the index finger [Hp (0.07)_P1] and that received by the distal phalanx [Hp (0.07)_P3] were compared.

Results

The median Hp (0.07)_P3/Hp (0.07)_P1 ratio per participant varied between 1.0 and 2.5 (based on 23 to 31 measurements per participant). The 271 paired measurements revealed a crude Hp (0.07)_P3/Hp (0.07)_P1 ratio of 1.67, significantly different from 1 (p = 0.0004, 95 % CI [1.35–2.07]). When adjusted on participant’s gender and mother vial activity, the ratio was similar (1.53, p = 0.003, 95 % CI [1.22–1.92]).

Conclusions

The study demonstrated a significant disparity that may exist between the radiation doses measured in the P1 and P3 positions of operators during ¹⁸F-FDG manipulation. These findings emphasize the importance of performing workplace dosimetry studies adapted to each radiopharmaceutical and manipulation thereof, aiming to guarantee optimal workers’ dosimetry monitoring schemes.

Trial registration

Hospital Nursing and Paramedical Research Program (PHRIP, 2011–2013) from the French Ministry of Health (DGOS), http://social-sante.gouv.fr/IMG/pdf/Resultats_PHRIP_2011.pdf

Radiation exposure to nuclear medicine staff involved in PET/CT practice in Serbia

The purpose of this work is to evaluate the radiation exposure to nuclear medicine (NM) staff in the two positron emission tomography-computed tomography centres in Serbia and to investigate the possibilities for dose reduction. Dose levels in terms of Hp(10) for whole body and Hp(0.07) for hands of NM staff were assessed using thermoluminescence and electronic personal dosemeters. The assessed doses per procedure in terms of Hp(10) were 4.2-7 and 5-6 μSv, in two centres, respectively, whereas the extremity doses in terms of Hp(0.07) in one of the centres was 34-126 μSv procedure(-1). The whole-body doses per unit activity were 17-19 and 21-26 μSv GBq(-1) in two centres, respectively, and the normalised finger dose in one centre was 170-680 μSv GBq(-1). The maximal estimated annual whole-body doses in two centres were 3.4 and 2.0 mSv, while the corresponding extremity dose in the later one was 45 mSv. Improvements as introduction of automatic dispensing system and injection and optimisation of working practice resulted in dose reduction ranging from 12 up to 67 %.

Extremity and eye lens dosimetry for medical staff performing vertebroplasty and kyphoplasty procedures

Measurements of doses to hands, legs and eyes are reported for operators in four different hospitals performing vertebroplasty or kyphoplasty. The results confirm that occupational doses can be high for interventional spine procedures. Extremity and eye lens doses were measured with thermoluminescent dosimeters positioned on the ring fingers, wrists, legs and near the eyes of interventional radiologists and neurosurgeons, over a period of 15 months. Doses were generally larger on the left side for all positions monitored. The median dose to the left finger was 225 μSv per procedure, although a maximum of 7.3 mSv was found. The median dose to the right finger was 118 μSv, but with an even higher maximum of 7.7 mSv. A median left eye dose of 34 μSv (maximum 836 μSv) was found, while the legs received the lowest doses with a median of 13 μSv (maximum 332 μSv) to the left leg. Annual dose to the hand assessed by the cumulated doses almost reached the annual dose limit of 500 mSv, while annual dose to the eyes exceeded the eye lens dose limit of 20 mSv yr(-1). Different x-ray systems and radiation protection measures were tested, like the use of lead gloves and glasses, tweezers, cement delivery systems and a magnetic navigation system. These measurements showed that doses can be significantly reduced. The use of lead glasses is strongly recommended for protection of the eyes.

Skin dose rate conversion factors after contamination with radiopharmaceuticals: influence of contamination area, epidermal thickness and percutaneous absorption

Skin contamination with radiopharmaceuticals can occur during biomedical research and daily nuclear medicine practice as a result of accidental spills, after contact with bodily fluids of patients or by inattentively touching contaminated materials. Skin dose assessment should be carried out by repeated quantification to map the course of the contamination together with the use of appropriate skin dose rate conversion factors. Contamination is generally characterised by local spots on the palmar surface of the hand and complete decontamination is difficult as a result of percutaneous absorption. This specific issue requires special consideration as to the skin dose rate conversion factors as a measure for the absorbed dose rate to the basal layer of the epidermis. In this work we used Monte Carlo simulations to study the influence of the contamination area, the epidermal thickness and the percutaneous absorption on the absorbed skin dose rate conversion factors for a set of 39 medical radionuclides. The results show that the absorbed dose to the basal layer of the epidermis can differ by up to two orders of magnitude from the operational quantity Hp(0.07) when using an appropriate epidermal thickness in combination with the effect of percutaneous absorption.