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.

Assessment of eye lens doses for workers during interventional radiology procedures.

The assessment of eye lens doses for workers during interventional radiology (IR) procedures was performed using a new eye lens dosemeter. In parallel, the results of routine individual monitoring were analysed and compared with the results obtained from measurements with a new eye lens dosemeter. The eye lens doses were assessed using Hp(3) measured at the level of the eyes and were compared with Hp(10) measured with the whole-body dosemeter above the lead collar. The information about use of protective measures, the number of performed interventional procedures per month and their fluoroscopy time was also collected. The assessment of doses to the lens of the eye was done for 50 IR workers at 9 Lithuanian hospitals for the period of 2012-2013. If the use of lead glasses is not taken into account, the estimated maximum annual dose equivalent to the lens of the eye was 82 mSv.

Patient doses in paediatric CT: feasibility of setting diagnostic reference levels.

Despite the fact that doses to paediatric patients from computed tomography (CT) examinations are of special concern, only few data or studies for setting of paediatric diagnostic reference levels (DRLs) have been published. In this study, doses to children were estimated from chest and head CT, in order to study the feasibility of DRLs for these examinations. It is shown that for the DRLs, patient dose data from different CT scanners should be collected in age or weight groups, possibly for different indications. For practical reasons, the DRLs for paediatric chest CT should be given as a continuous DRL curve as a function of patient weight. For paediatric head CT, DRLs for a few age groups could be given. The users of the DRLs should be aware of the calibration phantom applied in the console calibration for different paediatric scanning protocols. The feasibility of DRLs should be re-evaluated every 2-3 y.

Management of patient doses and diagnostic reference levels in X-ray radiography in Lithuania.

Management of patient doses and determination of national or local diagnostic reference levels (DRLs) are important parts of a quality control program in X-ray diagnostics. In Lithuania, national DRLs for specific radiographic examinations are comparatively higher than those recommended by the European Commission (EC) and the International Atomic Energy Agency (IAEA). A survey of entrance surface doses (ESDs) was performed to investigate the reasons for exceeding the European and the IAEA DRLs. The first measurements showed that the average ESD for standard patients and for all examinations exceeded DRLs at approximately 25 % of the hospitals. The main problems were the use of low kilovolt technique, the lack of automatic exposure control systems or improper adjustment of them as well as inadequate training of the staff. After corrective actions, the ESD measurements were repeated. The results showed that the average patient doses were reduced almost everywhere. An additional patient dose survey for establishing new DRLs in radiography taking into account the advantages of new equipment to indicate directly the kerma area product (KAP) values was done. The ESD values were calculated from the KAP-values. The data were analysed, and the average and third quartile values were calculated. The new DRLs, in terms of ESDs, were reduced significantly in almost all radiography examinations. They are equal or lower than the IAEA and EC DRLs. Especially at thorax spine LAT, lumbar spine LAT, hip joint AP, pelvis AP and abdomen AP they are half the IAEA DRLs.

Results of a patient dose survey on diagnostic radiology in Lithuania.

One of the most effective means towards optimisation of radiation protection for patients undergoing radiodiagnostic examinations are the diagnostic reference levels. In order to ensure the effective use of these levels, they have to be set properly. National characteristics, such as the conditions of the radiological equipments, the training of the staff, the availability of quality assurance systems, etc., have to be taken into account when these levels are established. Measurements under real conditions were considered as the best tools to achieve these reference levels. With an aim to establish the Lithuanian national diagnostic reference levels, the nationwide survey of entrance surface doses received by the patients during the most typical X-ray examinations has been performed. The most common types of examinations, such as chest PA, skull PA and LAT, abdomen AP, lumbar spine AP and LAT, thorax spine AP and LAT, and hip joint AP, were included in the list of procedures under consideration. Hospitals of different size and levels using different X-ray machines were represented in the survey. The standard thermoluminescence dosemeter techniques with pellets attached to the skin of the patient in the centre of radiation field were applied. The data were analysed statistically, and the averages and 75th percentile were calculated. The results show that the Lithuanian diagnostic reference levels might be rather close to the ones promoted by the International Atomic Energy Agency and the European Commission.