Diagnostic Reference Levels for Adult Nuclear Medicine Imaging Established from the National Survey in Korea

Diagnostic Reference Levels in PET Imaging at Chulabhorn Hospital, Thailand

Diagnostic reference levels (DRLs) are an important tool for controlling radiation exposure and ensuring safety in medical applications. In Thailand, DRL data have been gathered and established for nuclear medicine diagnostics since 2021. However, there is a lack of information on PET imaging examinations. At the National Cyclotron and PET Scan Centre, Chulabhorn Hospital, radiopharmaceuticals are produced for medical imaging and research, and a wide range of PET/CT and PET/MRI examinations are performed. Our objective was to investigate the administered activity of radiopharmaceuticals in patients undergoing PET imaging, especially the existing data on DRLs in medical diagnostic imaging. Methods: This was a retrospective study on nuclear medicine patients at the National Cyclotron and PET Scan Centre in 2023. Statistical analysis, including the mean and the 75th percentile values, was conducted to determine DRLs according to the International Commission on Radiological Protection guidelines. Results: The center performed 8,711 PET/CT and PET/MRI studies with 13 protocols in 2023. The most commonly administered activity was 18F-FDG in oncology and neurology examinations, with DRLs of 186.11 and 136.16 MBq, respectively. These values were notably almost twice lower than several reports in other countries. Conclusion: There is a lack of comprehensive data on most DRLs for PET imaging at this center because of the nonwidespread use of several radiopharmaceuticals. However, the lower DRLs for 18F-FDG can highlight the need for ongoing investigation toward the establishment of local DRLs, as well as assurance on the safety and efficiency of radiation used in nuclear medicine.

Establishment of National Diagnostic Reference Levels for Administered Activity in Diagnostic Nuclear Medicine in Thailand

The diagnostic reference level (DRL) is a patient-exposure optimization tool used to evaluate radiation doses in medical imaging and provide guidance for protection from them. In Thailand, nuclear medicine DRLs have not been established yet. Therefore, this study surveyed dose levels in routine nuclear medicine procedures to provide national DRLs (NDRLs). Methods: NDRLs in Thailand were established by investigating the administered activity of radiopharmaceuticals in nuclear medicine examination studies. The NDRLs were determined on the basis of the 75th percentile (third quartile) of administered activity distribution as recommended by the International Commission on Radiological Protection. As part of a nationwide survey, datasets for the period between June 1, 2018, and August 31, 2019, were collected from 21 Thailand hospitals with nuclear medicine equipment. All hospitals were asked to report the nuclear medicine imaging devices in use, the standard protocol parameters for selected examinations, the injected activities, and the ages and weights of patients. All data were calculated to determine Thailand NDRLs, which were compared with international NDRLs. Results: The data reported by the 21 hospitals consisted of 4,641 examinations with SPECT or SPECT/CT for general nuclear medicine and 409 examinations with PET. The most widely performed examinations for SPECT were bone, thyroid, oncology, and cardiovascular imaging. The NDRLs for SPECT or SPECT/CT agreed well with published NDRLs for Europe, the United States, Japan, Korea, Kuwait, and Australia. In contrast, the NDRLs for 18F-FDG PET in oncology studies were higher than for Japan, Korea, Kuwait, and Australia but lower than for the United States, the United Kingdom, and the European Union. Conclusion: This study presents NDRL results for adults in Thailand as a way to optimize radiation protection in nuclear medicine imaging. Moreover, the reported injected activity levels were comparable to those of other countries.

National and local diagnostic reference levels for adult18F-FDG and CT in Jordanian PET/CT: findings and implications in practice

This study aims to report the findings of Jordanian national diagnostic reference level (NDRL) survey for fluorodeoxyglucose (18F-FDG) and local diagnostic reference level (LDRL) of computed tomography (CT) used for attenuation correction and anatomical localisation (AC-AL); and AC and diagnostic CT (AC-DX) within the context of whole-body WB and half-body HB adult oncology PET/CT scanning. Two-structured questionnaires were prepared to gather the necessary information: dosimetry data, patient demographics, equipment specification, and acquisition protocols for identified18F-FDG PET/CT procedures. The NDRL and achievable dose were reported based on the 75th and 50th percentiles for18F-FDG administered activity (AA), respectively. The LDRL was reported based on the 50th percentile for (CTDIvol) and (DLP). Data from 562 patients from four Jordanian PET/CT centres were collected. The survey revealed that Jordanian NDRL for AA (303 MBq) was within the acceptable range compared to the published-peer NDRL data (240-590 MBq). However, the18F-FDG AA varied across the participated PET/CT centres. The reported LDRL CTDIvoland DLP of CT used for (AC-AL) was 4.3 mGy and 459.3 mGy.cm for HB CT scan range, and 4.1 mGy and 659.9 mGy.cm for WB CT scans. The reported LDRL for CTDIvoland DLP for HB CT was higher when compared with the United Kingdom (3.2 mGy and 310 mGy.cm). Concurrently, in the context of WB CT, the reported values (i.e. CTDIvol and DLP) were also higher than both Kuwait (3.6 mGy and 659 mGy.cm) and Slovenia (3.6 mGy and 676 mGy.cm). The reported HB CT(AC-DX) was higher than Nordic, New Zealand and Swiss NDRLs and for WB (AC-DX) CT it was higher than Swiss NDRLs. This study reported the first Jordanian NDRL for18F-FDG and LDRL for HB and WB CT associated with18F-FDG PET/CT scans. This data is useful for Jordanian PET/CT centres to compare their LDRL to the suggested DRLs and utilise it in the process of optimising CT radiation doses.

Administered dosage and effective dose estimated from 81Rb-rubidium hydroxide for lung ventilation scintigraphy using 81mKr noble gas

The aim of this study was to estimate the administered dosage of 81mKr noble gas as calculated by the radioactivity of 81Rb-rubidium hydroxide (81RbOH). The administered dosage was regarded as the total amount of 81mKr noble gas. The radioactivity of 81mKr was calculated using the radioactivity of 81RbOH at the examination, the beginning of inhalation, the inhalation duration and the attenuation volume from the generator to the patient for 81mKr noble gas. In addition, we created an Internet survey and asked National University Hospital in Japan to respond to questions regarding the parameters of concern. Survey responses were provided by 38 hospitals (response rate was 90.5%). Twenty-seven hospitals (64.3%) examined lung ventilation scintigraphy using 81mKr noble gas. The mean administered dosage and the effective dose of lung ventilation scintigraphy using 81mKr noble gas were 35.8 ± 22.1 GBq and 0.97 ± 0.60 mSv, respectively.

Enhancing Nuclear Medicine Practice in Saudi Arabia: Advocating for Comprehensive Guidelines and Local Diagnostic Reference Levels

INTRODUCTION

 Diagnostic reference levels (DRLs) were initially introduced by the International Commission on Radiation Protection (ICRP). It refers to the measured quantity of administered activity (MBq) in nuclear medicine imaging studies and is a type of investigation level. DRL is recommended to prevent excessive radiation exposure to patients while maintaining adequate image quality. It should not be implemented as a dose constraint or dose limit. The Saudi Food and Drug Authority (SFDA) is the primary government body responsible for reporting national diagnostic reference levels (NDRLs) for diagnostic medical imaging technologies in Saudi Arabia. Only NDRLs for computed tomography, general X-ray, and mammography have been published and enforced locally. This study aims to establish local DRLs for nuclear medicine imaging procedures at King Abdulaziz University Hospital, Saudi Arabia, preparing for compliance proof once required by local authorities.

METHOD

 Data were collected from all machines, and six common protocols were studied, with data from 50 patients of standard body size for each identified protocol. The study was conducted retrospectively, and the 50th percentile was then calculated for each scan.

RESULTS

Both protocols for renal scans administered the lowest doses to patients (130 MBq and 148 MBq), respectively. The highest dose administered to patients was found to be in bone scans (1110 MBq).

CONCLUSION

The study establishes local DRLs for nuclear medicine imaging in our institution. Median activity dosages in renal, thyroid, and parathyroid imaging were comparable to locally and internationally published DRLs. However, they are higher in cardiac and bone imaging compared to local Saudi DRL and DRL in the European Union and the USA, likely due to the adopted protocols. These highlight the need for modifying the protocols to fulfill optimization efforts. These findings serve as a foundation for compliance with future regulatory requirements, ensuring patient safety and maintaining imaging quality in Saudi healthcare.

The establishment of national diagnostic reference levels for adult SPECT-CT in Saudi Arabia

This study aims to introduce national diagnostic reference levels (NDRLs) for adult hybrid single photon emission computed tomography (SPECT-CT) in nuclear medicine (NM) departments in the Kingdom of Saudi Arabia. The administered activity (AA) of radiopharmaceuticals, volume-weighted computed tomography dose index (CTDIvol) and dose length product (DLP) for ten hybrid SPECT/CT examinations were collected and analysed for one year. The median of AA, CTDIvoland DLP for each dose quantity was derived and the suggested national DRLs were determined based on the 75thpercentile for all identified SPECT-CT examinations. A comparison of the defined adult NDRLs in Saudi Arabia with the published data of other countries was performed. Although there are no significant variations of the proposed NDRL of AA between countries, the proposed NDRLs of the integrated CT metrics exceed the published data in most procedures. NM departments are urged to consider optimisation for both image quality and radiation protection.

National Diagnostic Reference Levels for Nuclear Medicine in Qatar

Nuclear medicine (NM) started in Qatar in the mid-1980s with a 1-head γ-camera in Hamad General Hospital. However, Qatar is expanding, and now Hamad Medical Corp. has 2 NM departments and 1 PET/CT Center for Diagnosis and Research, with several hybrid SPECT/CT and PET/CT cameras. Furthermore, 2 new NM departments will be established in Qatar in the coming 3 y. Therefore, there is a need to optimize radiation protection in NM imaging and establish diagnostic reference levels (DRLs) for the first time in Qatar. This need is not only for the NM part of the examination but also for the CT part, especially in hybrid SPECT/CT and PET/CT. Methods: Data for adult patients were collected from the 3 SPECT/CT machines in the 2 NM facilities and from the 2 PET/CT machines in the PET/CT center. The 75th percentile values (also known as the third quartile) were considered preliminary DRLs and were consistent with the most commonly administered activities. The results for various general NM protocols were described, especially ^99mTc-based radiopharmaceuticals and PET/CT protocols including mainly oncologic applications. Results: The first DRLs for NM imaging in Qatar adults were established. The values agreed with other published DRLs, as was the case, for example, for PET oncology using ¹⁸F-FDG, with DRLs of 258, 230, 370, 400, and 461-710 MBq for Qatar, Kuwait, Korea, the United Kingdom, and the United States, respectively. Similarly, for cardiac stress or rest myocardial perfusion imaging using ^99mTc-methoxyisobutylisonitrile, the DRLs were 926, 976, 1,110, 800, and 945-1,402 MBq for Qatar, Kuwait, Korea, the United Kingdom, and the United States, respectively. Conclusion: The optimization of administered activity that this study will enable for NM procedures in Qatar will be of great value, especially for new departments that adhere to these DRLs.

Radiation Dose Assessment for Myocardial Perfusion Imaging: A Single Institution Survey

OBJECTIVE

This study aims to establish a local diagnostic reference level (LDRL) for single-photon emission tomography/computed tomography (SPECT/CT) and positron emission tomography/CT (PET/CT) with respect to myocardial perfusion imaging (MPI).

MATERIALS AND METHODS

The acquisition protocol and dosimetry data on the MPI procedures of five SPECT/CT scans and one PET/CT scan were collected. Data on technitum-99m sestamibi (^99mTc-sestamibi), ^99mTc-tetrofosmin, thallium-201 (²⁰¹Tl), and rubidium-82 (⁸²RB) were all collected from one centre via questionnaire booklets. Descriptive data analysis was used to analyse all variables, and the 50th percentile was used to analyse each radiation dose quantity.

RESULTS

The reported 50th percentile dose for a one-day stress/rest protocol using ^99mTc-sestamibi (445/1147 MBq) and ^99mTc-tetrofosmin (445/1147 MBq) and for a two-day stress/rest protocol using ^99mTc-sestamibi (1165/1184 MBq) and ^99mTc-tetrofosmin (1221/1184 MBq) are in good agreement with reported national diagnostic reference levels (NDRLs). However, the dose from the study data on a one-day stress/rest protocol using ^99mTc-sestamibi was more than the 50th percentile dose from the Brazilian data (370/1110 MBq) on a similar protocol, and the dose from the study data on a two-day stress/rest protocol using ^99mTc-tetrofosmin was more than the 50th percentile dose (1084/1110 MBq) from the United States data on MPI scans. Regarding the computed tomography (CT) portion of the SPECT/CT framework, the 50th percentile doses were lower than all the identified doses in the data considered in the literature reviewed. However, regarding the CT component of the PET/CT MPI scans, the ⁸²RB dose was more than the recorded doses in the CT data in the published literature.

CONCLUSION

This study determined the LDRL of five SPECT/CT protocols and one PET/CT MPI protocol. The results suggest that there may be opportunities to optimise the patient radiation burden from administered activities in patients undergoing SPECT examinations and the CT components associated with ⁸²RB PET/CT scans without compromising diagnostic image quality.

Nationwide survey on radiation doses received by patients in nuclear medicine imaging procedures

National diagnostic reference levels (DRLs) are essential tools for optimizing protocols and protecting patients from an unjustified radiation exposure. The aim of this study was to conduct a nationwide survey of adult patient doses received from nuclear medicine (NM) procedures and to update national DRL (NDRL) values for most common procedures. Data on the radioactivity administered to standard adult patients were collected from all Lithuanian hospitals using NM applications in practice, between 2017 and 2022. Twelve of the most commonly performed NM diagnostic procedures: myocardial perfusion scintigraphy (two parts), thyroid scintigraphy, lung perfusion scintigraphy, bone scintigraphy, dynamic renal scintigraphy (divided into two procedures), parathyroid scintigraphy, hepatobiliary scintigraphy, lymphoscintigraphy, neuroendocrine tumour scan, and oncology positron emission tomography/computed tomography (PET/CT) imaging were included. The 75th percentile of the dose distribution was estimated for establishing NDRLs. During the data collection period, the NM imaging equipment was upgraded. The procedures were completed with 12 single photon emission computed tomography (SPECT) and SPECT/CT gamma cameras (2 with cadmium zinc telluride (CZT) detectors), 2 cardiac-centred gamma cameras with CZT detectors, and 2 PET/CT scanners. Data were collected on 7979 activities administered to the patients. For each procedure, depending on its frequency, 50-580 administered radiopharmaceutical activities were selected. Based on the collected data, NDRLs were updated in 2021 for three procedures. A large part of the procedures were performed with scanners manufactured between 2008 and 2011. In the past few years, the main Lithuanian hospitals that provide NM services have updated their SPECT/CT systems. In the future, the data collection process should be continued in order to reassess DRLs with respect to new scanning systems (e.g. with CZT detectors and newer PET/CT technology). Variations in the prescribed radiopharmaceutical activities showed that optimization and harmonization procedures may be performed in some hospitals.

Simultaneous effect of gamma and Wi-Fi radiation on gamma-H2Ax expression in peripheral blood of rat: A radio-protection note

INTRODUCTION

Nuclear medicine patients are isolated in a room after the injection of a radiopharmaceutical. They may be active Wi-Fi option of its smartphone mobile or other environmental radiofrequency waves. The hypothesis of this study was the evaluation of increased biological effects of the simultaneous exposure to gamma-ray and the Wi-Fi waves by measuring the level of the increased double strand-breaks DNA in peripheral blood lymphocyte in the rat.

MATERIALS AND METHODS

Fifty male Wistar rats were exposed for 2, 24, and 72 h only by Wi-Fi, 99m Tc, and simultaneously by Wi-Fi and 99m Tc. The power density levels of Wi-Fi emitter at 15 cm was 4.2nW/ c m 2 . An activity of 100 μCi of 99m Tc was injected intraperitoneally. Blood samples were taken by cardiac puncture following general anesthesia. Mononuclear cells are extraction by Ficoll-Hypaque density gradient centrifugation. The number of gamma-H2AX foci per nucleus was counted by flow cytometry. The statistical differences between experimental groups at 2, 24, and 72 h were determined with a repeated measure's analysis of variance. The significant difference between groups at the same time was analyzed with the Kruskal-Wallis Test.

RESULTS

The manner of gamma-H2AX expression was not the same for three groups in time. The number of gamma-H2AX foci between the three groups was a significant difference after 72 h.

CONCLUSION

Simultaneous Wi-Fi and gamma-ray exposures can increase the number of double-strand break DNA in peripheral blood lymphocytes to exposure of gamma-ray to 72 h after technetium injection in the rat.

Diagnostic Reference Levels for nuclear medicine imaging in Austria: A nationwide survey of used dose levels for adult patients

PURPOSE

To assess dose levels in routine nuclear medicine (NUC) procedures in Austria as a prior to a legislative update of the National Diagnostic Reference Levels (NDRL).

METHOD

As part of a nationwide survey of common NUC-examinations between June 2019 and November 2019, data sets were collected from 33 Austrian hospitals with NUC equipment. All hospitals were asked to report the NUC imaging devices in use (model, type, year of manufacture, detector material, collimators), the standard protocol parameters for selected examinations (standard activity, collimator, average acquisition time, reconstruction type, use of time-of-flight) and to report data from 10 representative examinations (e.g. injected activity, weight), incl. the most common NUC-examinations for planar imaging/SPECT and PET. Median/mean values for injected activity were calculated and compared to current Austrian and international NDRL. A Pearson correlation coefficient was computed comparing different variables.

RESULTS

In total, all 33 hospitals (100% response rate) reported data for this study for 60 SPECT devices, 21 PET/CT devices and 23 scintigraphy devices. Fixed activity values for scintigraphy/SPECT and PET were employed by about 90% and 56% of the hospitals, respectively. The most widely performed examinations for scintigraphy/SPECT are bone imaging, thyroid imaging, renal imaging (with MAG3/EC) and lung perfusion imaging (in 88% of the hospitals) and F-18 FDG-PET studies for oncology indications (in 100% of the hospitals). Significant correlations were found for patient weight and injected activity (scintigraphy/SPECT), use of iterative reconstruction and injected activity (PET) as well as size of field-of-view and injected activity (PET).

CONCLUSIONS

The reported injected activity levels were comparable to those in other countries. However, for procedures for which NDRL exist, deviations in injected activities of >20% compared to the NDRL were found. These deviations are assumed to result mainly from advances in technology but also from deviations between NDRL and prescribed activities as given in the information leaflets of the radiopharmaceuticals.

NATIONAL DIAGNOSTIC REFERENCE LEVELS FOR NUCLEAR MEDICINE IN KUWAIT

The diagnostic reference level (DRL) is an optimization tool of patients exposure used to evaluate and provide guidance for radiation doses in medical imaging. In the past few decades, there has been a global increase in the number of diagnostic imaging procedures, including nuclear medicine procedures, and consequently the patient radiation exposure. This has encouraged international and national healthcare organizations to take actions and keep up with such changes to meet the expectations of an increasing use of ionizing radiation in medicine. The DRL in Kuwait was established by investigating the administered activity of radiopharmaceuticals and computed tomography (CT) radiation doses in hybrid imaging systems. The DRL were determined based on the 75th percentile of radiopharmaceuticals administered activity distribution as recommended by the international commission on radiation protection (ICRP). This study presents the establishment process and results of the first national DRLs for nuclear medicine procedures in Kuwait as a way to optimize radiation exposure. The DRLs determined in Kuwait are in good agreement with other published DRLs in Europe, Japan, Korea, Australia and the US.

Establishing Local Diagnostic Reference Level for Bone Scintigraphy in a Nigerian Tertiary Hospital

Background: It is of vital importance to optimize radiation dose to patients undergoing radionuclide bone scintigraphy. This is one of the most common nuclear medicine procedures in many parts of the world, including Nigeria. However, this study was carried out as part of a national survey to establish Diagnostic Reference Levels for common nuclear medicine procedures in Nigeria, to facilitate optimization of medical exposure. It is important to state here that nuclear medicine was recently introduced in the healthcare system in Nigeria with only two centres presently conducting these procedures. Methods: A cross-sectional study was carried out in the Nuclear Medicine department of a tertiary hospital in Southwest Nigeria to determine the preliminary local Diagnostic Reference Level (DRL) for radionuclide bone scintigraphy. One hundred and nine (109) patients who met the study criteria were involved in the study. Data was obtained from June 2017 to March 2019 and analyzed to obtain the 3rd quartile value of the distributed administered activity and achievable dose, the mean ± standard deviation, the anthropometric variables, and radiation dose to bone surface. Results: The result showed that the mean administered activity; achievable dose and DRL were 833.98± 106 MBq, 832.5 MBq and 895.4 MBq respectively. Furthermore, the calculated preliminary local DRL was found to be larger than values reported in studies done in Sudan, United Kingdom, Australia and ICRP. Conclusion: We concluded that the preliminary DRL from the study being the first of its kind in Nigeria is high due to lack of experience from practitioners. However, values obtained are still within international best practice range which when optimize will go a long way to reduce medical exposure without compromising image quality.