Evaluation of the performance of digital x-ray systems in pelvis radiography.

The aim of this study was to investigate the performance of eight digital radiography systems and to optimise the dose-image quality relationship for digital pelvis radiography. The study involved eight digital radiography systems used for general examinations at Vilnius University Hospital Santaros Klinikos. An anthropomorphic pelvic phantom (CIRS, US) was used to simulate a patient undergoing clinical pelvis radiography. Dose quantities ESD (entrance surface dose), DAP (dose area product) and exposure parameters (kVp, mA, mAs) were measured and the effects on the images were evaluated, considering physical CNR (contrast to noise ratio) and observer-based evaluations as image quality metrics. Increasing the tube voltage by 5 kVp from standard protocol led to a reduction in radiation dose (DAP) by 12-20% with a slight impact on image quality (CNR decreases by 2-10%). There was an inter-observer variability in image rating across different equipment (kappa value between 0 and 0.3); however, both observers agreed that increasing kVp up to 85-90 kV had no effect on perceived image quality. The results indicate that optimisation strategies should be tailored specifically for each X-ray system since significant performance differences and wide variations in radiation dose exist across various digital radiography systems used in clinical settings. The use of high kVp can be used for dose optimisation in digital pelvis radiography without compromising image diagnostic accuracy.

EFOMP's protocol quality controls in PET/CT and PET/MR.

This article presents the protocol on Quality Controls in PET/CT and PET/MRI published online in May 2022 by the European Federation of Organisations for Medical Physics (EFOMP), which was developed by the Working group for PET/CT and PET/MRI Quality Control (QC) protocol. The main objective of this protocol was to comprehensively provide simple and practical procedures that may be integrated into clinical practice to identify changes in the PET/CT/MRI system's performance and avoid short- and long-term quality deterioration. The protocol describes the quality control procedures on radionuclide calibrators, weighing scales, PET, CT and MRI systems using selected and measurable parameters that are directly linked to clinical images quality. It helps to detect problems before they can impact clinical studies in terms of safety, image quality, quantification accuracy and patient radiation dose. CT and MRI QCs are described only in the context of their use for PET (attenuation correction and anatomical localization) imaging. Detailed step-by-step instructions have been provided, limiting any misinterpretations or interpersonal variations as much as possible. This paper presents the main characteristics of the protocol illustrated together with a brief summary of the content of each chapter. A regular QC based on the proposed protocol would guarantee that PET/CT and PET/MRI systems operate under optimal conditions, resulting in the best performance for routine clinical tasks.

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 with99mTc-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 and99mTc 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 with99mTc, 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 of99mTc 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.

A NATIONAL SURVEY OF TRACEABILITY OF ACTIVITY METERS IN LITHUANIAN HOSPITALS.

The activity of prescribed radiopharmaceuticals, which are administered for diagnostic and therapeutic purposes, strongly depends on the accuracy of the measuring equipment used in nuclear medicine. This study presents the current status of uncertainty measurements of activity meters used in Lithuanian hospitals. During 2016-2021, the Ionizing Radiation Metrology Laboratory of the Center for Physical Sciences and Technology, which is the National Metrology Institute, performed a comparison of activity meters in the nuclear medicine departments of Lithuanian hospitals. Responses of 16 activity meters that were used in the daily hospital practice were compared with the reference standard. In total, around 150 measurements of activity of diagnostic, therapeutic and calibration radionuclides in different sources and geometries were fulfilled. The results of the maximum deviation were determined to be 8.9% for calibration sources, 18.3% for diagnostic radionuclides and 20.1% for radionuclides used for therapeutic purposes.

Occupational exposure in a PET/CT facility using two different automatic infusion systems.

PURPOSE: The aim of this study was to measure the occupational exposure using active personal dosimeters (APD) in the PET/CT department at different stages of the operation chain i.e. radiopharmaceutical arrival, activity preparation, dispensing, injection, patient positioning, discharge and compare the radiation exposure doses received using two automatic injection/infusion systems. This paper also reflects optimization processes that were performed to reduce occupational exposure. METHODS: Measured APD data were analysed for medical physicists, radiology technologists and administrative staff from 2014 till 2018. For dispensing and injecting 18F-FDG, the automatic infusion/injection system IRIDE (Comecer, Italy) or the automatic fractionator ALTHEA (Comecer, Italy) with wireless injection system WIS (Comecer, Italy) were used. Radiation exposure optimization methods were applied during the data collection period (installation of the transport port, patient management, APD alarm threshold and etc.). RESULTS: Radiology technologists who perform injection procedures, regardless of the automatic infusion system, received the highest radiation exposure dose. The average doses to the radiology technologists per one study were 1.72 ± 0.33 µSv and 1.16 ± 0.11 µSv with ALTHEA/WIS and IRIDE system, respectively. The average dose for accompanying the patient to the PET/CT scanner and scan procedure was 0.52 ± 0.07 µSv. For the medical physicists, the average dose was 0.29 ± 0.09 µSv. The measured dose for administrative staff was 0.30 ± 0.15 µSv. CONCLUSIONS: Occupational exposure can be effectively optimized by different means including staff monitoring with APD, implementation of radiation safety culture and the usage of automatic infusion systems.