Terms Of Hp Research Articles

Dose Response of Personnel OSL Dosimeter to the Cesium-137 and 80 kVp X-ray Exposure

Over the years, several types of dosimeters have been introduced for accurate dose assessment. The OSL dosimeter is one of them. It is used to monitor personnel dose from external exposure. In this paper, dose response of OSL dosimeters in terms of Hp(10) to Cs‑137 gamma and 80 kVp X‑ray radiation will be studied. The dosimeters were irradiated using Cs‑137 gamma and 80 kVp X‑ray to 0.5 mSv, 1 mSv, 3 mSv, 5 mSv, and 10 mSv at a distance of 200 cm, and all of them were subsequently read. Half of the dosimeters that were previously irradiated with a dose of 1 mSv and 5 mSv were read 30 times. The other half of the dosimeters were re-read on day 30 and day 60 from the initial reading. The study shows that relations between measured dose and exposure dose for Cs‑137 gamma and 80 kVp X‑ray irradiation are linear with correlation coefficients (R2) of 0.9997 and 0.9987, respectively. When the OSL dosimeters were read repeatedly, a dose reduction for each reading occured by 0.4 % and 0.5 % on Cs‑137 gamma and 80 kVp X‑ray, respectively. Dose reading on day 60 after Cs‑137 gamma irradiation showed fading of 3.6 % and 2.7 % on OSL dosimeter exposed to 1 mSv and 5 mSv, respectively, whereas fading effect on 80 kVp X‑ray irradiation showed values of 5.9 % and 8.8 % for the two doses.

Evaluation of personal dose equivalents during positron emission tomography and computed tomography imaging

This study aimed to evaluate the annual occupational radiation exposure of technologists during PET/CT imaging in 2020 and 2021. Eleven nuclear medicine technologists were monitored at the PET/CT department. The personal dose equivalents (PDEs) for staff members, measured in terms of Hp (10) and Hp (0.07), were assessed annually, considering both deep and surface doses. PDEs were quantified using a thermoluminescent detector (LiF:Mg:Ti)). The average and range of PDEs and extremity doses (mSv) for the technologists were as follows: 4.5 (0.1–13.4) for Hp (10), 4.63 (0.1–13.9) for Hp (0.07), and 2.5 (0.2–17.5) for extremity, respectively. The results indicated that staff members are exposed to high-energy gamma rays while preparing radiopharmaceuticals, injections, and image acquisition. Therefore, proper handling of radiopharmaceuticals and patient management during the acquisition of parameters are crucial for maintaining the occupational dose within the defined limit.

Characterization of small radiophotoluminescence dosemeter in terms of HP(0.07) for extremity dose monitoring of medical personnel.

An additional extremity monitoring using a ring badge must be appropriately conducted for inhomogeneous exposure around radiation workers' extremity. Commercially available glass dosemeters are characterized in terms of Hp(0.07) for the application of additional extremity monitoring. A series of experiments demonstrated that the response of the model GD-352M radiophotoluminescence dosemeter fully matched the IEC's criteria for an extremity dosemeter for medical personnel. Although the model GD-302M has excellent angular dependence, the material and the shape of energy compensation filter still need to be optimized to improve its energy dependence in the range between 30 and 100keV. The combine use of both types of glass dosemeters for 'paired dosemeter' together with introduction of a simple algorithm may be a promising method to improve the response in the energy range below 20keV.

EURADOS IC2019exteye- a self-funded intercomparison for extremity and eye lens dosemeters organised by EURADOS working group 2.

The European Radiation Dosimetry Group (EURADOS) has been organising regular, self-funding, external dosimetry intercomparisons (ICs) since 2008. IC2019exteye, for extremity and eye lens dosemeters, attracted 113 systems (68 extremity and 45 eye lens) from 60 institutes with participants from 26 countries around the world. Irradiations were carried out in accredited European irradiation facilities in terms of Hp(0.07)/or Hp(3) in the ranges: photon energy: 16-662keV, beta mean energy 250-1000keV, dose: 0.5mSv to 1Sv, maximum angle of incidence: ±60°. This paper describes the IC2019exteye set-up, irradiation plan and coordination with an overview of the main conclusions. Out of the total of 113 systems, 57 reported results for photons only and 56 reported both photon and beta. In general, the participants showed very satisfactory performances with the medians of all Hp(0.07) and Hp(3) response values very close to unity.

Staff occupational exposure and ambient doses resulting from patients undergoing nuclear medicine procedures’

Ultrasound personnel can be occupationally exposed to ionizing radiation from radioisotopes during ultrasonography imaging of patients who received radioactive material. Thus, radiation safety assessment is required to ensure that the ultrasonography physicians practices conform with the international guidelines and that dose limits are not exceeded. This study aimed to measure staff exposure during ultrasound investigations of such patients who received radioactive material in molecular imaging procedures such positron emission tomography (PET) and single photon emission computed tomography (SPECT). Occupational doses, in terms of Hp (10) (deep dose), Hp (0.07) (skin dose) and ambient dose were monstered using calibrated thermos-luminescent dosimeters (TLDs) to ensure occupational doses exposures for the ultrasonographers over 1 year at King Faisal Specialist Hospital and Research Center in Riyadh, Saudi Arabia. The overall mean of Hp(10), Hp(0.07) for an annual occupational dose of 0.4 mSv and ambient dose (mSv) were (M) in ultrasound room, Hp(10) of 1.7 mSv and Hp(0.07) of 1.72 mSv in the Hot Lab, and Hp(10) of 0.4 mSv and Hp(0.07) of 0.02 mSv in the Stress Room. Occupational exposure was below the annual dose limits (20.0 mSv) for all practitioners, as well the extremities dose was below the annual dose limits of 500 mSv. In conclusion, since staff exposure which highly depends on radioisotope characteristics and protection measures can vary significantly for different personnel, continuous serial careful assessment of working conditions is recommended to ensure occupational doses exposures remain below annual limits.

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

BackgroundSince 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.ResultsThe 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.ConclusionsImaging 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.

ESTIMATION OF PERSONAL DOSE EQUIVALENT HP(0.07) USING CASO4:DY TEFLON DISC-BASED EXTREMITY DOSEMETER.

The radiation workers in India use extremity dosemeter in occupational areas where there is likelihood of receiving significant dose to extremities of the body. Algorithm used for the estimation of whole body dose and extremity dose of wrist are same and is based on slab phantom calibration. However, internationally, different phantoms are recommended for calibration of dosemeter used for extremity and whole body. The recommended quantity for estimation of dose to extremity is the personal dose equivalent Hp(0.07) at 0.07mm depth. In light of this, an algorithm was developed for estimation of wrist dose in terms of Hp(0.07) based on calibration performed on ISO recommended pillar phantom. Performance of the dosemeter for the estimation of Hp(0.07) with new algorithm was carried out at different angular exposures of photon beams and mixed field of photon and beta. Comparison of results obtained for two types of ISO phantoms (slab and pillar) is also performed for photon beams to highlight the uncertainty caused due to the use of the slab phantom. In case of beta radiation, it was found that the size and shape of the phantom has very little influence in the response of the dosemeter. Performance of the dosemeter using ISO slab and ISO pillar phantoms for beta radiation using the prevalent algorithm was carried out and found to be within the uncertainty limits laid down by ISO except at angle 60°.

Evaluation of different types of lithium fluoride thermoluminescent detectors for ring dosimetry in nuclear medicine

Nuclear medicine staff is primarily exposed to their fingers during radionuclide manipulation. About 20% of these workers have risk to exceed the hand dose limit. Therefore, monitoring with ring dosimeters in terms of Hp(0.07) is advised. Most ring dosimeters make use of lithium fluoride (LiF) thermoluminescent detectors (TLDs). Different types of LiF TLDs exist, each with their advantages and disadvantages. The goal of this work was to evaluate the performance of three different LiF TLD types (MCP-N, MTS-N and MCP-Ns) for ring dosimetry during manipulation of the more novel radionuclides Lu-177, Ga-68 and I-131 within radionuclide imaging and therapy, and to provide recommendations for the most accurate dosimetric follow-up of the dose to the hands. This was done by combining measurements with TLDs and theoretical modelling of the TLD responses using Monte Carlo radiation transport simulations and microdosimetric modelling of the TLD relative luminescence efficiency. It was concluded that MTS-N TLDs are best suited for measuring doses from Lu-177 and I-131 if more than 1 mm polycarbonate equivalent shielding is provided. However, MCP-N TLDs have less than 20% under-response and are thus also acceptable in case high sensitivity is important. MCP-Ns TLDs were found to be best suited for measuring doses from Ga-68, and from Lu-177 and I-131 if less than 1 mm polycarbonate equivalent shielding is provided. The recommended TLD type strongly depends on both the manipulated radionuclide and the amount of shielding between the radionuclides and the fingers (syringe thickness and potential additional shielding around the syringe). But the approach presented here for the theoretical modelling of the Hp(0.07) response can easily be applied to select the most appropriate TLD type for other radionuclides or other amounts of shielding.

Interlaboratory comparison exercise using OSL personal dosimeters between the LMRI-DEN/UFPE, Brazil, and LCD/LAF-RAM, Nicaragua.

The aim of this paper is to present the results obtained in the intercomparison exercise organized by the Ionizing Radiation Metrology Laboratory at the Federal University of Pernambuco (LMRI-DEN/UFPE) and the Radiation Physics and Metrology Laboratory (LAF-RAM) of the National Autonomous University of Nicaragua, Managua (UNAN-Managua). The comparison aimed to assess the technical capabilities of the Dosimetry Calibration Laboratory (LCD) belonging to LAF-RAM for the irradiation of personal dosimeters in terms of Hp(d) magnitudes with a 137Cs radiation beam. The BeO OSL dosimeters were shipped by LMRI-DEN/UFPE to LAF-RAM for irradiation in March 2020. The evaluation of the Z-Score value obtained in the intercomparison was satisfactory for all irradiations of the dosimeters in the Hp (d) magnitude.

Radiation Eye Dose for Physicians in CT Fluoroscopy-Guided Biopsy.

It is important to evaluate the radiation eye dose (3 mm dose equivalent, Hp (3)) received by physicians during computed tomography fluoroscopy (CTF)-guided biopsy, as physicians are close to the source of scattered radiation. In this study, we measured the radiation eye dose in Hp (3) received by one physician during CTF in a timeframe of 18 months using a direct eye dosimeter, the DOSIRISTM. The physician placed eye dosimeters above and under their lead (Pb) eyeglasses. We recorded the occupational radiation dose received using a neck dosimeter, gathered CT dose-related parameters (e.g., CT-fluoroscopic acquisition number, CT-fluoroscopic time, and CT-fluoroscopic mAs), and performed a total of 95 procedures during CTF-guided biopsies. We also estimated the eye dose (Hp (3)) received using neck personal dosimeters and CT dose-related parameters. The physician eye doses (right and left side) received in terms of Hp (3) without the use of Pb eyeglasses for 18 months were 2.25 and 2.06 mSv, respectively. The protective effect of the Pb eyeglasses (0.5 mm Pb) on the right and left sides during CTF procedures was 27.8 and 37.5%, respectively. This study proved the existence of significant correlations between the eye and neck dose measurement (right and left sides, R2 = 0.82 and R2 = 0.55, respectively) in physicians. In addition, we found significant correlations between CT-related parameters, such as CT-fluoroscopy mAs, and radiation eye doses (right and left sides, R2 = 0.50 and R2 = 0.52, respectively). The eye dose of Hp (3) received in CTF was underestimated when evaluated using neck dosimeters. Therefore, we suggest that the physician involved in CTF use a direct eye dosimeter such as the DOSIRIS for the accurate evaluation of their eye lens dose.

Assessment of eye doses to staff involved in interventional cardiology procedures in Kuwait.

In this study, which is the first of its kind in the gulf region, eye doses of interventional cardiologists and nurses were measured using active dosimeters for left and right eyes, in 60 percutaneous coronary interventions in three main hospitals in Kuwait. The dose given in terms of Hp(0.07) per procedure when ceiling suspended screens were used by main operators ranged from 18.5 to 30.3 µSv for the left eye and from 12.6 to 23.6 µSv for the right eye. Taking into account typical staff workload, the results show that the dose limit of 20 mSv/year to the eyes can be exceeded for interventional cardiologists in some situations, which demonstrates the need of using additional effective radiation protection tools, e.g. protective eye spectacles, in addition to the regular and proper use of ceiling suspended screens. With indications of increase in workload, the need for availability of a dedicated active dosimeter for the regular monitoring of eye doses is emphasized.

THE POTENTIAL TO USE TLD MEASUREMENTS TO VALIDATE THE OCCUPATIONAL RADIATION PROTECTION AT THE DEPARTMENT OF NUCLEAR MEDICINE.

Diagnostic examinations in nuclear medicine increase. This can cause a higher radiation burden to the personnel. The aim of this study was to create and apply a method to validate the occupational radiation protection at the Department of Nuclear Medicine using thermoluminescence dosemeters (TLD). Occupational doses in- and outside of the department and the dose rate distribution around the positron emission tomography/computed tomography (PET/CT) were validated in terms of Hp(10) using TLD-100. Backscatter correction factors were estimated to implement the TLD measurements on different materials. After correction for backscatter, the result indicates that doses in- and outside of the department are below recommended values and dose limits. The highest and the lowest dose rate were measured beside the 18F-autoinjector and the PET/CT gantry, respectively. The method of using TLD gives a good estimate of how the occupational radiation protection performs at the Department of Nuclear Medicine and can thus help in the optimization of radiation protection.

Design and validation of a Monte Carlo Simulation model for estimation of Skin dose Hp( 0.07), Deep dose Hp(10) and Eye dose Hp(3) in Nuclear Medicine and PET/CT

Survey meters used in nuclear medicine facilities are most often calibrated in terms of Hp(10), the Deep Dose equivalent at 10 mm in tissue. Skin dose Hp(0.07) and Eye dose Hp(3) are not routinely monitored in real time. The purpose of this study was to determine dose rate constants for Hp(10), Hp(3) and Hp(0.07) for a range of commonly used radionuclides using Monte Carlo Simulation.

Occupational doses to the eye lens in pediatric and adult noncardiac interventional radiology procedures.

To assess occupational lens exposure in a mixed interventional radiology department, comparing pediatric and adult procedures. To analyze the correlation between the lens dose and the doses measured at the chest and collar level and the kerma-area product (PKA ). For 17months, three radiologists performing both pediatric and adult interventions were monitored by means of 14 dosimeters per worker: 12 single-point optically stimulated luminescent (OSL) dosimeters calibrated in terms of Hp (0.07) were placed on the inside and outside of two pairs of lead glasses, one for pediatric procedures and one for adult interventions; another whole-body OSL dosimeter calibrated in terms of Hp (10) was placed over the thyroid shield; finally, an additional active solid-state dosimeter, also calibrated for Hp (10), was worn on the chest, over the apron. Furthermore, a database was created to register the demographic and dosimetric data of the procedures, as well as the name of the radiologist acting as first operator. For the three radiologists, who performed 276-338 procedures/year (20% pediatric), cumulative annual doses to the left bare eye exceeded 20mSv (21-61mSv). Considering the glasses' protection, annual doses exceeded 6mSv (13-48mSv) for both eyes. No important differences were observed in lens dose per procedure between pediatric and adult interventions (0.16 vs 0.18, 0.12 vs 0.09, and 0.07 vs 0.07mSv), although lens dose per PKA was 4.1-4.5 times higher in pediatrics (5.8 vs 1.3, 3.3 vs 0.8, and 2.6 vs 0.6µSv/Gy·cm2 ) despite a similar use of the ceiling-suspended screen. Lens doses were highly correlated with collar readings (with Pearson coefficients [r] ranging from 0.86 to 0.98) and with chest readings (with r ranging from 0.75 to 0.93). However, slopes of the linear regressions varied greatly among radiologists. There is real risk of exceeding the occupational dose limit to the eye lens in mixed interventional radiology rooms if radiation protection tools are not used properly. Regular monitoring of the lens dose is recommended, given lens exposure might easily exceed 6mSv/yr. Using a collar dosimeter for this purpose might be suitable if it is preceded by an individualized regression analysis. The same radiation protection measures should be applied to interventional radiologists regardless of whether they are treating pediatric or adult patients.

Standardization of the absorbed dose at 3 mm depth in tissue in a 90Sr/90Y beta radiation field

The reduction of the dose limit for the eye lenses of occupational exposed workers drew the attention of authorities to review the monitoring, the calibration method and the performance of the individual dosimeters. Calibration laboratories are expected to perform dosimeter calibrations and tests in standardized and reliable conditions. In this work, the 90Sr/90Y beta radiation beam of the Beta Secondary Standard system was characterized. Beam standardization was achieved by measuring the absorbed dose rate at 3 mm in tissue, ?T(3). A reliable procedure for calibrating eye lens dosimeters in terms of Hp(3) in the 90Sr/90Y beta radiation field was established.

BeOSL dosemeters and new ICRU operational quantities: Response of existing dosemeters and modification options

The energy response for angles of incidence of 0° and 60° of current BeOSL Hp(10)-, Hp(3)-, Hp(0,07)- and H*(10) dosemeters for photon radiation has been expressed in terms of the new operational quantities Hp, Dlens, Dlocal skin, and H* proposed by ICRU. Results show the Hp(3)- and Hp(0,07) dosemeters can be used for Dlensand Dlocal skin with minor modifications to the system calibration. The whole body Hp(10) and area H*(10) dosemeters, however, show a pronounced over response in terms of the new quantities Hp and H* in the energy range below 40 keV. For the whole body dosemeter, we have investigated, by means of Monte Carlo simulations, how the use of different filter materials with higher Zeff and higher density could improve the response of the single element dosemeter in terms of Hp and identified filters that could achieve an IEC 62387 compliant response down to approximately 20 keV photon energy, assuming current IEC limits. In an alternative approach, a two-element algorithm, making use of the reading of the Hp(0,07) element of the dosemeter has been developed, which delivers a Hp-response fulfilling current IEC limits down to 15 keV, albeit with increased measurement uncertainty.

Staff radiation dose and estimated risk in an interventional radiology department

In interventional radiology attendant staff can be exposed to significant doses from the radiation scattered from the patient, giving rise to heterogeneous energy distribution, exposure occurring over extended periods of time. Protection of staff is a prime concern, also including reducing the risk of carcinogenesis. With only limited published studies available, as in for instance in regard to lens opacifications, further evaluation of staff exposures and assessment of radiation protection techniques and measures are crucial. Present study has sought to evaluate staff radiation exposure in a radiology department that performs interventional procedures. Annual occupational exposures were obtained for 32 personnel (6 females and 26 males) in a radiology department at a tertiary hospital. Personal dose equivalent Hp (d) was measured in terms of Hp (0.07) (shallow dose) and Hp (10) (deep dose). The measurements were made over a period of two consecutive years, 2017 and 2018, use being made of TLD-100 thermoluminescent dosimeters. In units of mSv, the corresponding average annual dose equivalent and range for Hp (10) and Hp (0.07) were 4.6 ± 7.0 (0.1–25.5) and 5.1 ± 7.3 (0.1–25.5). Notably, 16% of staff received doses that were greater than the annual dose limit. Since Hp (10) offers a conservative evaluation of effective dose, evaluation of the working environment is necessary in seeking to ensure dose values remain below annual dose limits.

CONVERSION FACTOR FROM DOSEMETER READING TO AIR KERMA FOR NUCLEAR WORKER USING ANTHROPOMORPHIC PHANTOM FOR FURTHER CONVERSION FROM AIR KERMA TO ORGAN-ABSORBED DOSE.

Estimation of cancer risk based on the organ-absorbed dose is underway for the Japanese Epidemiological Study on Low-Dose Radiation Effects (J-EPISODE). The reconstruction method for the organ-absorbed dose follows the approach adopted in the IARC 15-Country Collaborative Study, which examined the dosemeter response to photon exposure for the old film badge (FB) type, a multi-element FB and a thermoluminescence dosemeter. Until 2000, the dosemeters used in Japan were almost the same in the IARC study, so IARC study data could be used as they were. However, since 2000, the type of dosemeter has been replaced with active personal dosemeters (hereafter called electronic personal dosemeters), radio-photoluminescent glass dosemeters (Glass badge) and optically stimulated luminescence dosemeters (Luminess badge). Hence, it was necessary to collect these data again. A dosemeter response experiment was conducted using a device that irradiated an anthropomorphic phantom in the Japan Atomic Energy Agency calibration laboratories. The aim of the paper is to provide a conversion factor from reading in terms of Hp(10) to air kerma for realistic conditions for further conversion from air kerma to organ-absorbed dose. The obtained dosemeter responses for the dosemeter types currently used in Japan were consistent with those in the IARC study. These data will be utilized for J-EPISODE in reconstructing the organ-absorbed dose.

Results of the EURADOS 2017 intercomparison for whole body neutron dosemeters (IC2017n)

The European Radiation Dosimetry Group (EURADOS) has set up intercomparison exercises for personal dosemeters on a regular basis. In 2017, the second EURADOS intercomparison for neutron dosemeters (IC2017n) took place. The intercomparison concerned the performance of neutron dosemeters provided by individual monitoring services to measure neutron personal dose equivalent, Hp(10). The irradiations, which included exposures to neutrons and mixed fields of neutrons and photons as commonly encountered in workplaces, were performed in accredited irradiation facilities in terms of Hp(10). The range of energies used in the intercomparison extended from thermal to several MeV, with different dose values and angles used. The paper reports on the results of this intercomparison for whole body neutron dosemeters.

Individual monitoring with BeOSL dosemeters: New dosemeters for extremity and area dosimetry

To extend the applications of BeOSL technology beyond whole body dosimetry, three new dosemeters were developed: an eye lens dosemeter and a finger ring dosemeter using a single BeOSL detector element and a two-element area dosemeter for work place monitoring. This work describes the new dosemeters, provides data from the radiological characterization of the dosemeters according to IEC 62387 and addresses the issue of measurement uncertainty and detection limits achievable with the BeOSL systems. The response of the new extremity dosemeters in terms of Hp(3) and Hp(0,07) with respect to photon energy and angle of incidence fulfills the IEC 62387 requirements. The area dosemeter fulfills the IEC requirements for workplace monitoring but not the more stringent requirements for environmental dosimetry, due to an under-response for angles of incidence larger than 60°. The results of an uncertainty analysis for the dose evaluation of single element dosemeters show that detection limits in the range of 26 μSv–43 μSv can be achieved if dedicated background dosemeters are used.