Proposed DRLs for Mammography in Switzerland

OBJECTIVES

The aim of this study is to propose Diagnostic Reference Levels (DRLs) values for mammography in Switzerland. Methods: For the data collection, a survey was conducted among a sufficient number of centres, including 5 University hospitals, several cantonal hospitals, and large private clinics, covering all linguistic regions of Switzerland to be representative of the clinical practice. The data gathered contained the mean glandular dose (MGD), the compressed breast thickness (CBT), the mammography model and the examination parameters for each acquisition. The data collected was sorted into the following categories: 2D or digital breast tomosynthesis (DBT) examination, craniocaudal (CC) or mediolateral oblique (MLO) projection, and 8 categories of compressed breast thickness (CBT) ranging from 20mm to 100mm in 10mm intervals. Results: 24762 acquisitions acquired in 31 centres on 36 mammography units from 6 different manufacturers were collected. The analysis showed that the data reflects the practice in Switzerland.The results revealed that the MGD is larger for DBT than for 2D acquisitions for the same CBT. From 20-30mm to 90-100mm of CBT, the 75th percentile of the MGD values obtained increased from 0.81mGy to 2.55mGy for 2D CC acquisitions, from 0.83mGy to 2.96mGy for 2D MLO acquisitions, from 1.22mGy to 3.66mGy for DBT CC acquisitions and from 1.33mGy to 4.04mGy for DBT MLO acquisitions. Conclusion: The results of the survey allow us to propose Swiss DRLs for mammography according to the examination type (2D/DBT), projection (CC/MLO) and CBT. The proposed values are very satisfactory in comparison with other studies. .

Interventional Imaging Systems in Radiology, Cardiology, and Urology: Energy Consumption, Carbon Emissions, and Electricity Costs

Background: The energy demand of interventional imaging systems has historically been estimated using manufacturer-provided specifications rather than directly measured. Objective: To investigate the energy consumption of interventional imaging systems and estimate potential savings in such systems' carbon emissions and electricity costs through hypothetical operational adjustments. Methods: An interventional radiology suite, neurointerventional suite, radiology fluoroscopy unit, two cardiology laboratories, and two urology fluoroscopy units were equipped with power sensors. Power measurements logs were extracted for a single 4-week period for each radiology and cardiology system (all between June 1, 2022 and November 28, 2022) and for the 2-week period from July 31, 2023 to August 13, 2023 for each urology system. Power statuses, procedure timestamps, and fluoroscopy times were extracted from various sources. System activity was divided into off, idle (no patient in room), active (patient in room for procedure), and net-imaging (active fluoroscopic image acquisition) states. Projected annual energy consumption was calculated. Potential annual savings in carbon emissions and electricity costs through hypothetical operational adjustments were estimated using published values for Switzerland. Results: Across the seven systems, the mean power draw was 0.3-1.1 kW, 0.7-7.4 kW, 0.9-7.6 kW, and 1.9-12.5 kW in the off, idle, active, and net-imaging states, respectively. Across systems, the off state, in comparison with the idle state, exhibited a decrease in mean power draw of 0.2-6.9 kW (relative decrease, 22.2-93.2%). The systems had a combined projected annual energy consumption of 115,684 kWh (range, 3646-26,576 kWh per system). The systems' combined projected energy consumption occurring outside of the net-imaging state accounted for 93.0% (107,978/115,684 kWh) of projected total energy consumption (range, 89.2-99.4% per system). A hypothetical operational adjustment whereby all systems would be switched from the idle to off state overnight and on weekends (vs operated in idle mode 24/7) would yield potential annual savings in energy consumption of 144,640 kWh, carbon emissions of 18.6 MtCO2eq, and electricity costs of $37,896. Conclusion: Interventional imaging systems are energy intensive, with high consumption outside of image acquisition periods. Clinical Impact: Strategic operational adjustments (e.g., powering down idle systems) can substantially decrease interventional imaging systems' carbon emissions and electricity costs.

Endovascular Treatment and Peri-interventional Management of Ruptured Cerebrovascular Lesions During Pregnancy : Case Series and Case-based Systematic Review

PURPOSE

Hemorrhagic stroke, particularly occurring from ruptured cerebrovascular malformations, is responsible for 5-12% of all maternal deaths during pregnancy and the puerperium. Whether endovascular treatment is feasible and safe for both the mother and the fetus, is still a matter of debate. The main objective of this case series and systematic review was to share our multi-institutional experience and to assess the feasibility and safety of endovascular treatment during pregnancy, as well as the corresponding maternal and fetal outcomes based on currently available evidence.

METHODS

We report a case series of 12 pregnant women presenting with hemorrhagic stroke from ruptured cerebrovascular arteriovenous malformations or aneurysms who underwent endovascular treatment prior to delivery. A systematic literature review of pregnant patients with endovascular treated cerebrovascular malformations, published between 1995 and 2022, was performed. Clinical patient information, detailed treatment strategies, maternal and fetal outcomes as well as information on the delivery were collected and assessed.

RESULTS

In most patients the course was uneventful and an excellent outcome without significant neurological deficits (mRS ≤ 1) was achieved. Furthermore, the maternal outcome was not worse compared to the general population who underwent endovascular treatment of ruptured vascular brain lesions. Also, in most cases a healthy fetus was born.

CONCLUSION

Endovascular treatment of ruptured cerebrovascular malformations during pregnancy is safe and feasible regarding both aspects, the maternal and fetal outcomes. Still, a stronger knowledge base is needed to correctly approach future cases of intracranial hemorrhage in the pregnant population.

3D-printed iodine-ink CT phantom for radiomics feature extraction - advantages and challenges

BACKGROUND

To test and validate novel CT techniques, such as texture analysis in radiomics, repeat measurements are required. Current anthropomorphic phantoms lack fine texture and true anatomic representation. 3D-printing of iodinated ink on paper is a promising phantom manufacturing technique. Previously acquired or artificially created CT data can be used to generate realistic phantoms.

PURPOSE

To present the design process of an anthropomorphic 3D-printed iodine ink phantom, highlighting the different advantages and pitfalls in its use. To analyze the phantom's X-ray attenuation properties, and the influences of the printing process on the imaging characteristics, by comparing it to the original input dataset.

METHODS

Two patient CT scans and artificially generated test patterns were combined in a single dataset for phantom printing and cropped to a size of 26 × 19 × 30 cm3 . This DICOM dataset was printed on paper using iodinated ink. The phantom was CT-scanned and compared to the original image dataset used for printing the phantom. The water-equivalent diameter of the phantom was compared to that of a patient cohort (N = 104). Iodine concentrations in the phantom were measured using dual-energy CT. 86 radiomics features were extracted from 10 repeat phantom scans and the input dataset. Features were compared using a histogram analysis and a PCA individually and overall, respectively. The frequency content was compared using the normalized spectrum modulus.

RESULTS

Low density structures are depicted incorrectly, while soft tissue structures show excellent visual accordance with the input dataset. Maximum deviations of around 30 HU between the original dataset and phantom HU values were observed. The phantom has X-ray attenuation properties comparable to a lightweight adult patient (∼54 kg, BMI 19 kg/m2 ). Iodine concentrations in the phantom varied between 0 and 50 mg/ml. PCA of radiomics features shows different tissue types separate in similar areas of PCA representation in the phantom scans as in the input dataset. Individual feature analysis revealed systematic shift of first order radiomics features compared to the original dataset, while some higher order radiomics features did not. The normalized frequency modulus |f(ω)| of the phantom data agrees well with the original data. However, all frequencies systematically occur more frequently in the phantom compared to the maximum of the spectrum modulus than in the original data set, especially for mid-frequencies (e.g., for ω = 0.3942 mm-1 , |f(ω)|original  = 0.09 * |fmax |original and |f(ω)|phantom  = 0.12 * |fmax |phantom ).

CONCLUSIONS

3D-iodine-ink-printing technology can be used to print anthropomorphic phantoms with a water-equivalent diameter of a lightweight adult patient. Challenges include small residual air enclosures and the fidelity of HU values. For soft tissue, there is a good agreement between the HU values of the phantom and input data set. Radiomics texture features of the phantom scans are similar to the input data set, but systematic shifts of radiomics features in first order features, due to differences in HU values, need to be considered. The paper substrate influences the spatial frequency distribution of the phantom scans. This phantom type is of very limited use for dual-energy CT analyses.

The Discriminative Power and Stability of Radiomics Features With Computed Tomography Variations: Task-Based Analysis in an Anthropomorphic 3D-Printed CT Phantom

OBJECTIVES

The aims of this study were to determine the stability of radiomics features against computed tomography (CT) parameter variations and to study their discriminative power concerning tissue classification using a 3D-printed CT phantom based on real patient data.

MATERIALS AND METHODS

A radiopaque 3D phantom was developed using real patient data and a potassium iodide solution paper-printing technique. Normal liver tissue and 3 lesion types (benign cyst, hemangioma, and metastasis) were manually annotated in the phantom. The stability and discriminative power of 86 radiomics features were assessed in measurements taken from 240 CT series with 8 parameter variations of reconstruction algorithms, reconstruction kernels, slice thickness, and slice spacing. Pairwise parameter group and pairwise tissue class comparisons were performed using Wilcoxon signed rank tests.

RESULTS

In total, 19,264 feature stability tests and 8256 discriminative power tests were performed. The 8 CT parameter variation pairwise group comparisons had statistically significant differences on average in 78/86 radiomics features. On the other hand, 84% of the univariate radiomics feature tests had a successful and statistically significant differentiation of the 4 classes of liver tissue. The 86 radiomics features were ranked according to the cumulative sum of successful stability and discriminative power tests.

CONCLUSIONS

The differences in radiomics feature values obtained from different types of liver tissue are generally greater than the intraclass differences resulting from CT parameter variations.

Characterization of a computed radiography system for external radiotherapy beam dosimetry

A commercial computed radiography (CR) system was studied as an option for quantitative dosimetry quality assurance of external radiotherapy beams. Following the examination of influencing quantities, practical measurement procedures are discussed. Corrections were derived for image fading, an observed long-term response drift and the image length scale, which was found to be off by up to 2-3%. It is known that energy dependence is important for CR measurements. Therefore, signal-to-dose calibration curves and the energy dependence of the response were studied extensively using multiple photon and electron beam qualities. Doses which yield the same signal vary by up to tens of percent for different beam qualities. Results on the directional response of the plates are presented. It was found that rotations of up to 30° to 40° relative to perpendicular irradiation yield no significant change in response. Finally, the homogeneity of the response over the measurement region was studied for electrons and photons and a correction method is described. In summary, relative dose measurements with uncertainties of a few percent are feasible in regions of constant beam energy.

Optical properties of quantum-dot-doped liquid scintillators

Semiconductor nanoparticles (quantum dots) were studied in the context of liquid scintillator development for upcoming neutrino experiments. The unique optical and chemical properties of quantum dots are particularly promising for the use in neutrinoless double-beta decay experiments. Liquid scintillators for large scale neutrino detectors have to meet specific requirements which are reviewed, highlighting the peculiarities of quantum-dot-doping. In this paper, we report results on laboratory-scale measurements of the attenuation length and the fluorescence properties of three commercial quantum dot samples. The results include absorbance and emission stability measurements, improvement in transparency due to filtering of the quantum dot samples, precipitation tests to isolate the quantum dots from solution and energy transfer studies with quantum dots and the fluorophore PPO.

Indication of reactor ν(e) disappearance in the Double Chooz experiment

The Double Chooz experiment presents an indication of reactor electron antineutrino disappearance consistent with neutrino oscillations. An observed-to-predicted ratio of events of 0.944±0.016(stat)±0.040(syst) was obtained in 101 days of running at the Chooz nuclear power plant in France, with two 4.25 GW(th) reactors. The results were obtained from a single 10 m(3) fiducial volume detector located 1050 m from the two reactor cores. The reactor antineutrino flux prediction used the Bugey4 flux measurement after correction for differences in core composition. The deficit can be interpreted as an indication of a nonzero value of the still unmeasured neutrino mixing parameter sin(2)2θ(13). Analyzing both the rate of the prompt positrons and their energy spectrum, we find sin(2)2θ(13)=0.086±0.041(stat)±0.030(syst), or, at 90% C.L., 0.017<sin(2)2θ(13)<0.16.

Coupled molecular switches: a redox-responsive ligand and the redox-switched complexation of metal ions

1,1'-(OC2H4OTos)2-ferrocene was treated with various diaza-[n]-crown-m (n/m = 12/4, 15/5, 18/6) to give three ferrocene cryptands (n/m = 12/4 (FcCrypt), 15/5, 18/6). The complexation of Group 1 and 2 metal ions by FcCrypt leads to large shifts in the redox potentials (up to +500 mV relative to FcCrypt) and consequently to a drastic decrease in the binding strength (up to 10(8)) in the ferrocene cryptands. The redox potential of Fcpda (1,1'-N,N'-bis-(dipicol-2-ylamino)-3.3',4,4'-tetraphenylferrocene) can be modified reversibly by complexation of Zn2 (E(Fcdpa) = -0.13 V, E(Fcdpa-2Zn+) = +0.66 V and E(Fcdpa-Zn2+) = +0.72 V). The X-ray crystal structure of FcCrypt-Ca-(ClO4)2 . H2O was determined; Ca2+ is coordinated by six oxygen (Ca2+-O 238.7, 239.1, 239.5, 242.6, 243.6, 247.7 pm) and two nitrogen donors (Ca2+-N 256.1, 259.2 pm) and displays a short Fe-Ca2+ contact (402.7 pm). The stability constants of FcCrypt-Na+ (IgK=8.32 in CH3CN) and FcCrypt-K+ (IgK = 4.54 in CH3CN) were determined. The precise adjustment of complex stability and redox potentials of Fcdpa, Fcdpa-Zn2+, FcCrypt (+0.12 V), and FcCrypt-Na+ (+0.395 V) allows coupling of the redox-switchable ferrocene cryptand and the redox-responsive aminoferrocene. In a cyclic process starting from a mixture of Fcdpa+PF6- and FcCrypt-Na+ the addition of Zn(CF3SO3)2 raises the redox potential of Fcdpa+ to that of Fcdpa+-Zn2+. This complex oxidizes FcCrypt-Na+, while the oxidized crypt- and displays a drastically reduced affinity towards Na+, so that a mixture containing FcCrypt+, Fcdpa-Zn2+, and uncoordinated Na+ results. The alkali metal ion is recomplexed after cyclam-assisted removal of Zn2+ from the Fcdpa-Zn2+ complex, since Fcdpa is oxidized by FcCrypt+ with reformation of FcCrypt-Na+. Thus two independent chemical processes--the complexation/ decomplexation of Zn2+ and of Na+--are linked indirectly with mediation by electron-transfer reactions.

Ferrocene-cyclam: a redox-active macrocycle for the complexation of transition metal ions and a study on the influence of the relative permittivity on the coulombic interaction between metal cations

The reaction of 1,1'-ferrocene-bis(methylenepyridinium) salt with 1,4,8,11-tetraazacyclotetradecane-5,12-dione, followed by LiAlH4 reduction results in the formation of FcCyclam. Metal complexes of FcCyclam with M2+ = Co2+, Ni2+, Cu2+, and Zn2+ were synthesized from FcCyclam and the respective metal triflates. The complexation of Cu2+ and FcCyclam in CH3CN is preceeded by a rapid electron transfer, followed by a slower complex formation reaction and a reverse electron transfer. The protonation constants of FcCyclam and the stability constants for the Cu2+ complex of FcCyclam (logK = 9.26(4) for the formation of the [Cu(FcCyclam)]2+ complex) were determined in 1,4-dioxane/water 70:30 v/v, 0.1 moldm(-3), KNO3, 25 degrees C. By using FcCyclam one can selectively sense the presence of Cu2+ ions in the presence of Ni2+, Zn2+, Cd2+, Hg2+, and Pb2+ with a very large deltaE approximately 200 mV, depending on pH. The X-ray crystal structures of FcCyclam and of complexes with Co2+, Ni2+, Cu2+, and Zn2+ were determined and Fe-M2+ distances obtained: Fe-Co2+ 395.9, Fe-Ni2+ 385.4, Fe-Cu2+ 377.7, and Fe-Zn2+ 369.0 pm. The redox potential of FcCyclam is influenced in a characteristic manner by the complexation of M2+. A linear correlation of 1/r approximately/= deltaE [r = distance Fe-M2+ from crystal data, deltaE=-E1/2([M(FcCyclam)]2+) - E1/2(FcCyclam)] was found; this is indicative of a mainly Coulomb type interaction between the two metal centers. The nature of the Fe...M2+ interaction was also investigated by determining deltaE in several solvents (mixtures) of different dielectric constants epsilon. The expected relation of deltaE approximately/= 1/epsilon was only found at very high values of epsilon. At epsilon < 40 increased ion-pairing appears to reduce the effective positive charge at M2+ leading to progessively smaller values of deltaE with lowered epsilon. The dependence of deltaE and epsilon can be calculated semiquantitatively by combining the Fuoss ion-pairing theory with the Coulomb model.