Mean glandular dose values used for the mammography screening program in Poland according to the type of image registration system

Between 2007–2014, there have been considerable changes in the use of different types of detector systems at mammography facilities undertaking screening programs in Poland. The use of screen-film systems (termed SF systems) has largely decreased and been replaced by either computed radiography (termed CR systems) or digital radiography systems (termed DR systems); this inevitably affecting mean glandular dose values. The study aim was to evaluate changes of mean glandular dose values for a dose exposure of 4.5 cm (MGD4,5cmPMMA) achieved by using different image detectors. The study consisted of analysing 1499 protocols for quality control tests carried out by medical physicists at 16 Regional Coordination Offices in 2007, 2011, 2012 and 2013. The mean CR system values were higher than for SF systems; by 25% in 2011, by 26% in 2012, and by 28% in 2013. In subsequent years, the MGD4,5cmPMMA mean values for DR systems were higher than for SF systems by respectively 15%, 4% and 5%. Also in the subsequent years, the MGD4,5cmPMMA mean values for CR systems were higher than for DR systems by respectively 13%, 23% and 24%. In all cases, the MGD4,5cmPMMA mean values were within the acceptable level of 2.5 mGy. The MGD4,5cmPMMA mean values were different, depending on the detection system used for mammography screening in Poland

Trendy zmian wartości dawek promieniowania X w mammograficznych badaniach skriningowych w Polsce vs zmiany używanych rejestratorów obrazu

Na przestrzeni lat 2007–2014 znacznie zmieniły się rodzaje rejestratora obrazu w placówkach mammograficznych realizujących program badań przesiewowych w Polsce. Odsetek systemów z detektorem filmowym (zwanych dalej systemami SF — screen-film systems) zmniejszył się w znacznym stopniu. Zostały one zastąpione przez systemy z płytami obrazowymi (zwanymi dalej systemami CR — computed radiography systems) i systemami z pełnopolowym detektorem cyfrowym (zwanymi DR — digital radiography systems), co miało wpływ na dawkę promieniowania X otrzymywaną przez kobiety podczas badań. Celem niniejszej pracy była ocena zmian, jakim podlegają wartości średnich dawek gruczołowych dla ekspozycji 4,5 cm PMMA (MGD4,5cmPMMA) w związku ze zmianą rodzaju rejestratora obrazu. Materiał pracy stanowiło 1499 protokołów z kontroli przeprowadzonych przez fizyków z 16 wojewódzkich ośrodków koordynujących w latach 2007, 2011, 2012 i 2013. Analiza wyników wykazała, że w kolejnych latach, począwszy od roku 2011, wartości średnie MGD4,5cmPMMA dla systemów CR były wyższe niż dla systemów SF: o 25%, 26% i o 28%; dla systemów DR były wyższe niż dla systemów SF: o 15%, 4% i o 5%; dla systemów CR były wyższe niż dla systemów DR o 13%, 23% i o 24%. Jednak we wszystkich przypadkach wartości średnie MGD4,5cmPMMA były na akceptowalnym poziomie 2,5 mGy. Średnie wartości MGD4,5cmPMMA znacznie różnią się w zależności od stosowanego rejestratora obrazu

Average glandular doses reported by mammography units: how reliable are they?

Introduction. Average glandular dose (AGD) values displayed by mammography units are often used to compare doses with diagnostic reference levels, with acceptable and achievable dose levels given with in the European guidelines on breast cancer screening, or between mammography units. The aim of the work was to check the reliability of displayed AGD values by comparing them with independently calculated values. Material and methods. The comparison was performed for five mammography units, for 20 groups of patients (50 patients each), examined in various periods between the years 2015 and 2020. AGD values were calculated independently for the same patients using the results of measurements. Results. Observed differences between displayed and calculated doses affected their comparison with acceptable and achievable dose levels. Conclusions. The displayed AGD values should be used with caution. If reliable information on AGD values is needed, they should be independently calculated using the results of measurements

The impact of studying on the hippocampal volume in medical students and its correlation with the results of the Final Medical Examination : a single-centre, prospective observational cohort study

Purpose: The hippocampus forms part of the limbic system and is involved in the learning process; it is responsible for transferring information from short-term to long-term memory. The aim of our study was to assess the effect of intensive studying on hippocampal volume and whether this correlates with exam results. Material and methods: The analysis included volunteer final-year medical students who underwent 2 volumetric 3D T1 magnetic resonance imaging scans with an interval of 20 weeks: 19 weeks before and one week after the Final Medical Examination. FreeSurfer software was used to compare the volumes of the whole hippocampus and its subfields between the 2 measurements. We assessed correlations between changes in hippocampal volume and the time students spent studying, between changes in hippocampal volume and the results of the exam, and between time spent studying and exam results. Results: Forty participants (25 women and 15 men; mean age 25 years) were included in the analysis. The right hippocampus presubiculum area increased significantly over the study period (p = 0.029), whereas the volume of the left hippocampus remained unchanged. An increase in the volume of the right hippocampus correlated with longer study time (r = 0.371 in percentage and r = 0.397 in mm3) and better LEK exam results (r = 0.441 in percentage and r = 0.456 in mm3). Conclusions: Our research confirms the role of the hippocampus, particularly the subicular complex, in the process of learning and remembering, and suggest that the plastic abilities of the hippocampus depend on the intensity of learning and translate into better skills

Evaluation of imaging parameters of ultrasound scanners : baseline for future testing

Background: Regular quality control is required in Poland only for those methods of medical imaging which involve the use of ionizing radiation but not for ultrasonography. It is known that the quality of ultrasound images may be affected by the wearing down or malfunctioning of equipment. Material/Methods: An evaluation of image quality was carried out for 22 ultrasound scanners equipped with 46 transducers. The CIRS Phantom model 040GSE was used. A set of tests was established which could be carried out with the phantom, including: depth of penetration, dead zone, distance measurement accuracy, resolution, uniformity, and visibility of structures. Results: While the dead zone was 0 mm for 89% of transducers, it was 3 mm for the oldest transducer. The distances measured agreed with the actual distances by 1 mm or less in most cases, with the largest difference of 2.6 mm. The resolution in the axial direction for linear transducers did not exceed 1 mm, but it reached even 5 mm for some of the convex and sector transducers, especially at higher depths and in the lateral direction. For 29% of transducers, some distortions of anechoic structures were observed. Artifacts were detected for several transducers. Conclusions: The results will serve as a baseline for future testing. Several cases of suboptimal image quality were identified along with differences in performance between similar transducers. The results could be used to decide on the applicability of a given scanner or transducer for a particular kind of examination

Assessment of mammography equipment quality in mammography screening facilities in 2007 and 2011 in Poland

Wstęp. Celem pracy było sprawdzenie, czy po czterech latach od wprowadzenia w Polsce systemu kontroli jakości przesiewowych badań mammograficznych nastąpiła poprawa stanu aparatury mammograficznej i czy wzrósł poziom realizacji testów podstawowych i specjalistycznych tej aparatury.Materiał i metody. Materiał stanowiły protokoły pokontrolne sporządzone przez fizyków z 16 Wojewódzkich Ośrodków Koordynujących. Metody przeprowadzonych kontroli były oparte głównie na wymaganiach europejskich. W niniejszej pracy porównano wyniki dotyczące realizacji testów specjalistycznych, podstawowych i w nadzorze dla 293 mammografów w 2007 r. i 396 — w 2011 r.Wyniki. W 2011 r. w porównaniu z rokiem 2007 odnotowano spadek liczby pracowni z systemem analogowym, dla których testy podstawowe były wykonywane nieprawidłowo lub niewykonywane w ogóle. Wzrósł udział pracowni mammograficznych z systemem analogowym, dla których zaakceptowano wyniki testów w nadzorze. W roku 2011 nastąpił spadek maksymalnej oraz średniej wartości średniej dawki gruczołowej (AGD) dla ekspozycji fantomu z PMMA o grubości 4,5 cm. Porównanie wyników kontroli wykonanych w 2011 roku dla trzech grup systemów mammograficznych (analogowych, ucyfrowionych i cyfrowych) pokazuje, że wymagań nie spełniają najczęściej systemy ucyfrowione, charakteryzując się przy tym jednocześnie najwyższą średnią wartością AGD.Wnioski. Po czterech latach od wprowadzenia w Polsce systemu kontroli jakości przesiewowych badań mammograficznych nastąpiła znacząca poprawa stanu aparatury mammograficznej oraz wzrósł poziom realizacji testów podstawowych i specjalistycznych tej aparatury. Konieczne jest jednak jak najszybsze wprowadzenie w Polsce odpowiednich uregulowań prawnych dotyczących kontroli jakości mammograficznych systemów cyfrowych i ucyfrowionych w celu umożliwienia kompleksowej i rzetelnej oceny wszystkich pracowni mammograficznych w Polsce.Introduction. The purpose of this study was to assess whether over the four year period 2007–2011 after the implementation of the quality control program for mammography screening examinations in Poland, the quality of the mammography equipment improved and whether the quality level of basic and advanced tests performed at these facilities increased.Material and methods. The material for this study comprised control protocols from 2007 and 2011, prepared by the physicists from 16 Regional Coordinating Centres. The control methodology was mostly based on European Union recommendations. In this paper, the results of performing advanced, basic and supervising tests for 293 mammography units in 2007 and 396 in 2011 were compared.Results. In 2011, the number of facilities with analogue mammography units for which the basic tests were performed incorrectly or not performed at all, decreased in comparison to 2007. There was an increase in the number of facilities with analogue mammography units for which the results of supervising tests were acceptable. In 2011 the maximum and mean values of average glandular dose (AGD) for 4.5 cm thick PMMA phantom decreased. Comparison of the quality control results performed in 2011 for three types of mammography units (analogue, computed radiography and digital radiography) revealed that the computed radiography units fail the tests most often and yield the highest AGD values.Conclusions. Over the four year period after the implementation of the quality control system for mammography screening in Poland, the quality of the mammography equipment significantly increased, and also the level of basic and advanced tests performed at these polish facilities improved. However, adequate legal regulations for quality control systems for DR and CR units is urgently needed in order to implement a comprehensive and reliable evaluation of all mammography facilities in Poland

Reproducibility of intravoxel incoherent motion of liver on a 3.0T scanner : free-breathing and respiratory-triggered sequences acquired with different numbers of excitations

Purpose: To optimise the intravoxel incoherent motion (IVIM) imaging of the liver on a 3.0T scanner by assessing parameter reproducibility on free-breathing (FB) and respiratory-triggered (RT) sequences acquired with different numbers of signal averages (NSA). Material and methods: In this prospective study 20 subjects (M/F: 10/10; age: 25-62 years, mean: 39 years) underwent IVIM magnetic resonance imaging (MRI) on a 3.0T scanner using an 18-channel phase-arrayed coil and four different echo-planar sequences, each with 10 b values: 0, 10, 30, 50, 75, 100, 150, 200, 500, and 900 s/mm2. Images were acquired with FB and RT with NSA = 1-4 (FBNSA1-4, RTNSA1-4) and with NSA = 3-6 (FBNSA3-6, RTNSA3-6). Subsequently, for the assessment of reproducibility of IVIM-derived parameters (f, D, D*), each subject was scanned again with an identical protocol during the same session. IVIM parameters were calculated. The distribution of IVIM-parameters for each DWI sequence were given as the median value with first and third quartile. Inter-scan reproducibility for each IVIM parameter was evaluated using coefficient of variance and Bland-Altman difference. Differences between FB sequence and RT sequence were tested using non-parametric Wilcoxon signed-rank test. Results: Mean coefficient of variance (%) for f, D, and D* ranged from 60 to 64, from 58 to 84, and from 82 to 99 for FBNSA1-4 sequence; from 50 to 69, from 41 to 97, and from 80 to 82 for RTNSA1-4 sequence; from 22 to 27, 15, and from 70 to 80 for FBNSA3-6 sequence; and from 21 to 32, from 12 to, and from 50 to 80 for RTNSA3-6 sequence, respectively. Conclusions: Increasing the number of signal averages for IVIM acquisitions allows us to improve the reproducibility of IVIM-derived parameters. The sequence acquired during free-breathing with NSA = 3-6 was optimal in terms of reproducibility and acquisition time

Individual doses in screening mammography examinations performed with digital equipment in Poland

Background: The aim of this study was the estimation of individual doses for women participating in the mammography screening program in Poland, examined with digital systems. Material/Methods: Materials for this study included data obtained from 1800 exposures performed with the use of 9 different mammography units with digital systems. Exposure conditions (breast thickness after compression, high voltage, mAs value, the material of the anode and additional filter) were recorded during mammography screening examinations conducted for over one year in Poland. The collected data were used to determine individual doses in accordance with the method, which uses conversion factors for air kerma to the absorbed dose in the glandular tissue. The entrance air kerma for compressed breast exposure was determined on the basis of the measurements of the air kerma for the high-voltage value at which the exposure was performed, assuming a linear air kerma dependence on the tube load. Results: Individual doses established in 9 mammography facilities ranged from 0.40 mGy to 11.48 mGy for CR (computed radiography) systems and from 0.36 mGy to 5.80 mGy for DR (digital radiography) systems. The maximum value of the individual doses for CR systems was about 98% higher than for DR systems. The values of compressed breast thickness ranged from 2.0 cm to 7.6 cm for CR systems and from 2.1 cm to 11.4 cm for DR systems. The glandularity of breasts was from 9% to 100% for CR systems and from 3% to 97% for DR systems. The mean glandularity of breasts was 47% for CR systems and 29% for DR systems. Conclusions: One of the criteria for evaluating the suitability of digital systems in breast cancer screening in Poland should be the systematic evaluation of individual doses. In Poland, it is necessary to implement standardized methods of optimization of the exposure parameters for reducing individual doses to a minimum necessary to maintain the image quality

The threshold contrast thickness evaluated with different CDMAM phantoms and software

The image quality in digital mammography is described by specifying the thickness and diameter of disks with threshold visibility. The European Commission recommends the CDMAM phantom as a tool to evaluate threshold contrast visibility in digital mammography [1, 2]. Inaccuracy of the manufacturing process of CDMAM 3.4 phantoms (Artinis Medical System BV), as well as differences between software used to analyze the images, may lead to discrepancies in the evaluation of threshold contrast visibility. The authors of this work used three CDMAM 3.4 phantoms with serial numbers 1669, 1840, and 1841 and two mammography systems of the same manufacturer with an identical types of detectors. The images were analyzed with EUREF software (version 1.5.5 with CDCOM 1.6. exe file) and Artinis software (version 1.2 with CDCOM 1.6. exe file). The differences between the observed thicknesses of the threshold contrast structures, which were caused by differences between the CDMAM 3.4 phantoms, were not reproduced in the same way on two mammography units of the same type. The thickness reported by the Artinis software (version 1.2 with CDCOM 1.6. exe file) was generally greater than the one determined by the EUREF software (version 1.5.5 with CDCOM 1.6. exe file), but the ratio of the results depended on the phantom and diameter of the structure. It was not possible to establish correction factors, which would allow correction of the differences between the results obtained for different CDMAM 3.4 phantoms, or to correct the differences between software. Great care must be taken when results of the tests performed with different CDMAM 3.4 phantoms and with different software application are interpreted

Radiation dose in CT-guided microwave liver tumor ablation

Introduction.Ablation is one of most important methods of liver tumor treatment. However, radiation is one of disadvantages of CT-guided procedures including ablation. The purpose of this study is to assess the factors that have impact on radiation doses during CT-guided microwave liver tumor ablation. Material and methods.Radiation doses of CT-guided liver tumor ablations were collected in 127 patients. They were then compared in terms of number of lesions, lesion size and depth, use of additional localization needles and hydrodis­section as well as tumor location. Results.The median radiation doses of ablations of multiple tumors (2348 mGy*cm) were significantly higher (p = 0.03) than those of single tumors (1784 mGy*cm). No statistically significant differences were noted when other factors (lesion size, depth, location, use of localization needles and hydrodissection) were taken into consideration. Conclusions.The number of lesions is the most important factor in terms of expected radiation doses in CT-guided microwave liver tumor ablations