Intercomparison of TL dosimetry (DIMOND programme)

During DIMOND CA, a thermoluminescence dosimetry intercomparison has been performed, in order to ensure that all participants measure the same dose. After the calibrating and annealing procedures, 50 TLD pellets (in groups of five) of each participating country were sent to the coordinator to be irradiated with 'unknown' radiations (blind test). The irradiation conditions (8 different set-ups, one for each group of pellets per participant) were (i) one gamma irradiation (60Co), at air kerma in the range of 0.3 to 50.0 mGy, (ii) seven X ray irradiations, at air kerma in the range of 0.3 to 50.0 mGy, with tube potential in the range of 40 to 150 kV and a variety of filter combinations. Ten pellets (two groups) were used for background and transport dose evaluation. After measuring the TLDs, the participants sent the results to the coordinator for intercomparison. Irradiating set-up conditions, evaluated doses, as well as comparison of mean values with the 'true' nominal doses are presented and discussed

Application of European Commission reference dose levels in CT examinations in Crete, Greece

The purpose of this study was to apply European Commission reference dose levels (EC RDLs) to routine CT examinations. The dosimetric quantities proposed in the European Guidelines (EG) for CT are weighted computed tomography dose index (CTDIw) for a single slice and dose-length product (DLP) for a complete examination. Patient-related data as well as technical parameters for brain, chest, abdomen and pelvis examinations were collected for four CT scanners in the Euromedica Medical Center. Computed tomography dose index (CTDI) measurements were performed on each scanner and CTDIw, DLP and effective dose E were estimated for each type of examination for a random sample of 10 typical patients. Mean values of CTDIw had a range of 27.0-52.0 mGy for brain and 13.9-26.9 mGy for chest, abdomen and pelvis examinations. Mean values of DLP had a range of 430-758 mGy em for brain, 348-807 mGy cm for chest, 278-582 mGy cm for abdomen and 306-592 mGy cm for pelvis examinations. Mean values of E were 1.4 mSv for brain, 10.9 mSv for chest, 7.1 mSv for abdomen and 9.3 mSv for pelvis examinations. Results confirm that the Euromedica Medical Center meets EC RDLs for brain, abdomen and pelvis examinations, in terms of radiation dose and examination technique. As far as chest examination is concerned, although CTDIw of each scanner is within proposed values, the DLP is consistently exceeded, probably because of the large irradiation volume length L. It is anticipated that a reduction of L, or product mAs, or their combination, will reduce DLP without affecting image quality

High patient doses in interventional cardiology due to physicians' negligence: How can they be prevented?

Interventional cardiology procedures are usually associated with high patient doses and even deterministic radiation effects may occur. Expensive digital flat panels are preferably used to lower doses, and Athens General Hospital has recently installed one. However, this study shows that it is the cardiologists' practice that lowers patients' doses. Doses delivered to patients during two time periods (pre and after radiation protection training) on a total of 1196 coronary angiographies and 506 percutaneous transluminal coronary angioplasties were measured and analysed per cardiologist. Local reference levels (LRLs) were assessed and compared with the preliminary RLs provided by the European Research Program DIMOND. Results showed that although after the training patients' dose area product, fluoroscopy time, cumulative dose and number of images acquired were lowered, the situation remained unchanged for the cardiologist who delivered the highest doses. The question to answer next is how this bad practice can be prevented since no dose constraints apply to diagnostic or therapeutic procedures using ionising radiation. © The Author 2008. Published by Oxford University Press. All rights reserved

Radiation dose measurements to the interventional cardiologist using an electronic personal dosemeter

The aim of this study was to investigate the use of an electronic personal dosemeter (EPD) worn by a senior cardiologist in an Interventional Cardiology (IC) Laboratory of a busy cardiac centre and how the results could help in the evaluation of radiation protection equipment used. Patient samples consist of 28 patients (10 coronary angiographies (CAs) and 18 percutaneous transluminal coronary angioplasties (PTCAs)). Patient dose was measured with a dose-area product (DAP) meter. Cardiologist radiation dose value written on the EPD as well as the protective equipment used was collected. Between patient and cardiologist dose, a significant correlation was found in CA and a moderate correlation in PTCA. Mean cardiologist effective dose E per procedure was found to be 0.2 μSv in CA and 0.3 μSv in PTCA. EPD proved to be an easy, direct and straightforward way to measure the radiation dose that the cardiologist receives in an IC laboratory. © Oxford University Press 2004; All rights reserved

Radiation doses in paediatric interventional cardiology procedures

The objective was to investigate paediatric doses in coronary angiography (CA) and percutaneous transluminal coronary angioplasty (PTCA) in the largest cardiac hospital in Greece. Forty procedures were carried out by two board-certified senior interventional cardiologists. Data collected were: patient weight, height, age, fluoroscopy time (FT), total number of images (N) and kerma-area product (KAP). Median (range) age was 7.5 y (17 d to 17 y). Median FT, N and KAP were 4 min, 655, 2.1 Gy cm2 for CA and 12.1 min, 1296, 14.7 Gy cm2 for PTCA (corresponding adult diagnostic reference levels (DRLs) are: 6.5 min, 700, 45 Gy cm2 for CA and 15.5 min, 1000 and 85 Gy cm2 for PTCA). The highest percentage of cine dose was in newborns (0-1 y) (CA: 92% and PTCA: 100%). As age increased, cine dose percentage decreased, whereas total radiation dose increased. Median paediatric FT and N recorded reached or even exceeded adult DRL and should be optimised. Paediatric DRL should be set. © The Author 2009. Published by Oxford University Press. All rights reserved

Greek dose reference levels in pediatric pelvis computed tomography examinations

The fact that children do undergo computed tomography (CT) examinations similar to those for adults adults has been a research issue, especially since the former are exposed to greater risk levels (developing stochastic late effects, such as cancer) due to their increased radiosensitivity compared to the latter. In a previous research paper (Yakoumakis et al. 2009), the values of dose levels were recorded, analyzed, and compared with the reference values for groups of 0, 1, 5 and 10 y-old children for the regions of head, chest, and abdomen. In this paper, the same age group has been considered for measuring dose levels of the pelvic region. Scanning the pelvic region has been one of the most important CT examination procedures, in which unfortunately part of the lower abdomen region is included without adapting any pediatric protocols. Furthermore, the study determines whether the adjustment of the scanning parameters results in any possible reduction in the radiation dose levels to which the patient is being exposed during the examination. The present work also includes the Greek reference levels for the pelvic CT examination for the 5- and 10-y-old children that have been used for comparison against the European ones. Copyright © 2013 Health Physics Society

Comparison of a CCD and a flat-panel digital system in an Interventional Cardiology Laboratory

We evaluated the performances of angiographic units equipped with a flat-panel (FP) detector and image intensifier (II) charge-coupled device (CCD) in the Interventional Cardiology (IC) Department. Entrance dose rate and dose per image, along with the dose at the II level were measured using 2 mm copper sheets to simulate a patient. Image quality (IQ) was evaluated using a phantom. Doses increased with fluoroscopy level changing from low to high. FP presented higher doses than CCD. Periodic measurements showed differences of up to 35%. Low mode IQ did not significantly differ from normal and high mode for both systems. Low fluoroscopy mode was decided to be used routinely. Both X-ray systems performed within international recommendations for conventional systems with the exception of higher cine radiation doses and II dose rates, stressing the fact that more studies are required to investigate whether dose levels should be adjusted. © 2006 Oxford University Press

Quality control measurements for fluoroscopy systems in eight countries participating in the SENTINEL EU coordination action

Quality control (QC) is becoming increasingly important in relation to the introduction of digital medical imaging systems using X rays. It was, therefore, decided to organise and perform a trial on image quality and physical measurements. The SENTINEL toolkit for QC measurements of fluoroscopy systems containing equipment and instructions for their use in the assessment of dose and image quality circulated among participants in the trial. The participants reported on their results. In the present contribution, the impact of the trial on the selected protocols is presented. The Medical Physics and Bioengineering protocol appeared to be useful for QC, and also for digital systems. The protocol needs an additional section, or an addition to each section, to state compliance with the requirements. The circular cross-sections of the Leeds test objects need adaptation for rectangular flat panel detector (FPD) systems. Only one participant was able to perform the monitor test using MoniQA. This is due to the fact that assistance is required from the suppliers of the X-ray systems. This problem needs to be solved to apply MoniQA in practice. © The Author 2008. Published by Oxford University Press. All rights reserved

Cone beam ct in dental implant planning: How close are patient dosimetry results with data from phantom studies found in literature?

Advantages of Cone Beam Computed Tomography (CBCT) include high-quality 3D imaging and reduced radiation exposure with relatively low cost. In this study, patient radiation exposure in CBCT implant planning dentistry was measured in terms of Kerma Area Product (KAP). Data were obtained from 217 CBCT scans on 168 individuals using a CS9300 Carestream system. Scans were made using 80-90 kVp, 4-5 mA, 8 and 13.3 s exposure time (depending on voxel size) and a fixed field of view (FOV) of 10 × 10 cm2 (medium). Mean KAP was estimated using two voxel sizes 180 × 180 × 180 μm3 and 200 × 200 × 200 μm3 and found to be 399 and 314 mGycm2, respectively. Corresponding KAP values found in literature ranged between 210 and 2140 mGycm2. Mean E was estimated using conversion coefficient factors found in literature, according to FOV size and tube voltage value and found to range between 24 and 161 μSv. © The Author(s) 2019. Published by Oxford University Press. All rights reserved