National survey to set diagnostic reference levels in nuclear medicine single photon emission imaging in Croatia

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.

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.

National reference levels of CT procedures dedicated for treatment planning in radiation oncology

OBJECTIVE

To present results of the first national survey on reference levels of CT imaging performed for the treatment planning purposes in radiation oncology in Croatia.

METHODS

Data for CT protocols of five anatomical regions including head, head and neck, pelvis, breast, and thorax were collected at eight radiation oncology departments in Croatia. Data included volume CT dose index (CTDI_vol), dose-length product (DLP), scan length and set of acquisition and reconstruction parameters. Data on a total of 600 patients were collected. Median values of scan length, DLP and CTDI_vol were calculated for each acquisition protocol. Third quartiles of the median CTDI_vol and DLP values were proposed as the national radiotherapy planning reference levels (RPRL).

RESULTS

The largest CoV were assessed for RT Breast (63.8% for CTDI_vol), RT Thorax (79.7% for DLP) and RT H&N (21.2% for scan length). RT Head had the lowest CoV for CTDI_vol (1,9%) and DLP (17,2%), while RT Breast had the lowest coefficient of variation for scan length (12.8%). Proposed national RPRLs are: for RT Head CTDI_vol16cm = 62 mGy and DLP_16cm = 1738 mGy.cm; for RT H&N CTDI_vol16cm = 35 mGy and DLP_16cm = 1444 mGy.cm; for RT Breast CTDI_vol32cm = 16 mGy and DLP_32cm = 731 mGy.cm; for RT Thorax CTDI_vol32cm = 17 mGy and DLP_32cm = 865 mGy.cm; for RT Pelvis CTDI_vol32cm = 20 mGy and DLP_32cm = 1133 mGy.cm.

CONCLUSIONS

Results of this study show variations in CT imaging for treatment planning practice at the national level which call for optimization of procedures.

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.