Pathways towards sustainable concrete Coffetti, D.; Crotti, E.; Gazzaniga, G. ...
Cement and concrete research,
April 2022, 2022-04-00, 20220401, Letnik:
154
Journal Article
Recenzirano
This paper covers a wide range of alternative strategies to improve the sustainability of concrete. It firstly considers the relatively easy application of the latest technologies to manufacture ...traditional Portland cement, including carbon capture, utilization and storage technologies, and the use supplementary cementitious materials as Portland cement replacement. It then focuses on more complex processes such as the substitution of traditional constituents with alternative binders (both non-Portland clinker or alkali-activated materials), recycled aggregates and non-drinking water, up to the description of high-durability/high performance mixtures. This review also underlines the significant need to upgrade the existing standards, and the relevance of thriving the education of designers, researchers and contractors for the development and the diffusion, also thanks to good practice, of new concrete technologies. This research also proposes a new sustainability index for mortars and concretes, also manufactured with negative carbon footprint materials, modifying the Empathetic Added Sustainability Index (EASI).
Purpose:
This paper presents initial experimental results from a prototype of high dose rate (HDR) BrachyView, a novel in‐body source tracking system for HDR brachytherapy based on a multipinhole ...tungsten collimator and a high resolution pixellated silicon detector array. The probe and its associated position estimation algorithms are validated and a comprehensive evaluation of the accuracy of its position estimation capabilities is presented.
Methods:
The HDR brachytherapy source is moved through a sequence of positions in a prostate phantom, for various displacements in x, y, and z. For each position, multiple image acquisitions are performed, and source positions are reconstructed. Error estimates in each dimension are calculated at each source position and combined to calculate overall positioning errors. Gafchromic film is used to validate the accuracy of source placement within the phantom.
Results:
More than 90% of evaluated source positions were estimated with an error of less than one millimeter, with the worst‐case error being 1.3 mm. Experimental results were in close agreement with previously published Monte Carlo simulation results.
Conclusions:
The prototype of HDR BrachyView demonstrates a satisfactory level of accuracy in its source position estimation, and additional improvements are achievable with further refinement of HDR BrachyView's image processing algorithms.
The aim of this study was to optimize the dosimetric approach and to review the absorbed doses delivered, taking into account radiobiology, in order to identify the optimal methodology for an ...individualized treatment planning strategy based on (99m)Tc-macroaggregated albumin (MAA) single photon emission computed tomography (SPECT) images.
We performed retrospective dosimetry of the standard TheraSphere® treatment on 52 intermediate (n = 17) and advanced (i.e. portal vein thrombosis, n = 35) hepatocarcinoma patients with tumour burden < 50% and without obstruction of the main portal vein trunk. Response was monitored with the densitometric radiological criterion (European Association for the Study of the Liver) and treatment-related liver decompensation was defined ad hoc with a time cut-off of 6 months. Adverse events clearly attributable to disease progression or other causes were not attributed to treatment. Voxel dosimetry was performed with the local deposition method on (99m)Tc-MAA SPECT images. The reconstruction protocol was optimized. Concordance of (99m)Tc-MAA and (90)Y bremsstrahlung microsphere biodistributions was studied in 35 sequential patients. Two segmentation methods were used, based on SPECT alone (home-made code) or on coregistered SPECT/CT images (IMALYTICS™ by Philips). STRATOS™ absorbed dose calculation was validated for (90)Y with a single time point. Radiobiology was used introducing other dosimetric variables besides the mean absorbed dose D: equivalent uniform dose (EUD), biologically effective dose averaged over voxel values (BEDave) and equivalent uniform biologically effective dose (EUBED). Two sets of radiobiological parameters, the first derived from microsphere irradiation and the second from external beam radiotherapy (EBRT), were used. A total of 16 possible methodologies were compared. Tumour control probability (TCP) and normal tissue complication probability (NTCP) were derived. The area under the curve (AUC) of the receiver-operating characteristic (ROC) curve was used as a figure of merit to identify the methodology which gave the best separation in terms of dosimetry between responding and non-responding lesions and liver decompensated vs non-decompensated liver treatment.
MAA and (90)Y biodistributions were not different (71% of cases), different in 23% and uncertain in 6%. Response correlated with absorbed dose (Spearman's r from 0.48 to 0.69). Responding vs non-responding lesion absorbed doses were well separated, regardless of the methodology adopted (p = 0.0001, AUC from 0.75 to 0.87). EUBED gave significantly better separation with respect to mean dose (AUC = 0.87 vs 0.80, z = 2.07). Segmentation on SPECT gave better separation than on SPECT/CT. TCP(50%) was at 250 Gy for small lesion volumes (<10 cc) and higher than 1,000 Gy for large lesions (>10 cc). Apparent radiosensitivity values from TCP were around 0.003/Gy, a factor of 3-5 lower than in EBRT, as found by other authors. The dose-rate effect was negligible: a purely linear model can be applied. Toxicity incidence was significantly larger for Child B7 patients (89 vs 14%, p < 0.0001), who were therefore excluded from dose-toxicity analysis. Child A toxic vs non-toxic treatments were significantly separated in terms of dose averaged on whole non-tumoural parenchyma (including non-irradiated regions) with AUC from 0.73 to 0.94. TD50 was ≈ 100 Gy. No methodology was superior to parenchyma mean dose, which therefore can be used for planning, with a limit of TD15 ≈ 75 Gy.
A dosimetric treatment planning criterion for Child A patients without complete obstruction of the portal vein was developed.
The need of a fs-scale pulsed, high repetition rate, X-ray source for time-resolved fine analysis of matter (spectroscopy and photon scattering) in the linear response regime is addressed by the ...conceptual design of a facility called MariX (Multi-disciplinary Advanced Research Infrastructure for the generation and application of X-rays) outperforming current X-ray sources for the declared scope. MariX is based on the original design of a two-pass two-way superconducting linear electron accelerator, equipped with an arc compressor, to be operated in CW mode (1 MHz). MariX provides FEL emission in the range 0.2–8 keV with 108 photons per pulse ideally suited for photoelectric effect and inelastic X-ray scattering experiments. The accelerator complex includes an early stage that supports an advanced inverse Compton source of very high-flux hard X-rays of energies up to 180 keV that is well adapted for large area radiological imaging, realizing a broad science programme and serving a multidisciplinary user community, covering fundamental science of matter and application to life sciences, including health at preclinical and clinical level.
•3 MOSkins were assembled over a common rectal probe to perform in vivo dosimetry.•Mean discrepancy between measured and calculated doses was 2.2±6.9%.•89.2% of the measurements resulted in dose ...discrepancies within ±10%.•Discrepancy between planned and measured doses increases with planning time.
Three MOSkins dosimeters were assembled over a rectal probe and used to perform in vivo dosimetry during HDR brachytherapy treatments of vaginal cancer. The purpose of this study was to verify the applicability of the developed tool to evaluate discrepancies between planned and measured doses to the rectal wall.
MOSkin dosimeters from the Centre for Medical Radiation Physics are particularly suitable for brachytherapy procedures for their ability to be easily incorporated into treatment instrumentation. In this study, 26 treatment sessions of HDR vaginal brachytherapy were monitored using three MOSkin mounted on a rectal probe. A total of 78 measurements were collected and compared to doses determined by the treatment planning system.
Mean dose discrepancy was determined as 2.2±6.9%, with 44.6% of the measurements within ±5%, 89.2% within ±10% and 10.8% higher than ±10%. When dose discrepancies were grouped according to the time elapsed between imaging and treatment (i.e., group 1: ≤90min; group 2: >90min), mean discrepancies resulted in 4.7±3.6% and 7.1±5.0% for groups 1 and 2, respectively. Furthermore, the position of the dosimeter on the rectal catheter was found to affect uncertainty, where highest uncertainties were observed for the dosimeter furthest inside the rectum.
This study has verified MOSkin applicability to in-patient dose monitoring in gynecological brachytherapy procedures, demonstrating the dosimetric rectal probe setup as an accurate and convenient IVD instrument for rectal wall dose verification. Furthermore, the study demonstrates that the delivered dose discrepancy may be affected by the duration of treatment planning.
Measurements aimed at investigating the quenching of sensitivity of Gafchromic EBT3 films irradiated with charged particles at radiotherapy energy levels have been carried out. Films have been ...irradiated with beams of protons and carbon ions of interest for Hadron Therapy. The broadening of pencil beams in water phantom as a function of initial energy has been studied and the quenching of EBT3 film sensitivity has been quantified. A procedure for correcting the dose images obtained by means of EBT3 films has been improved and its application to an irradiation test has show the validity of the proposed methodology.
•Study of spread out of protons and carbon ions PBs in water.•Study of the sensitivity quenching of Gafchromic EBT3 films for high LET radiation.•Study of algorithms for the correction of sensitivity quenching effects.•Verification of the proposed correction method applied to a measured dose image.
PRDM proteins are tissue-specific transcription factors often deregulated in diseases, particularly in cancer where different members have been found to act as oncogenes or tumor suppressors. PRDM5 ...is a poorly characterized member of the PRDM family for which several studies have reported a high frequency of promoter hypermethylation in cancer types of gastrointestinal origin. We report here the characterization of Prdm5 knockout mice in the context of intestinal carcinogenesis. We demonstrate that loss of Prdm5 increases the number of adenomas throughout the murine small intestine on an Apc(Min) background. By using the genome-wide ChIP-seq (chromatin immunoprecipitation (ChIP) followed by DNA sequencing) and transcriptome analyses we identify loci encoding proteins involved in metabolic processes as prominent PRDM5 targets and characterize monoacylglycerol lipase (Mgll) as a direct PRDM5 target in human colon cancer cells and in Prdm5 mutant mouse intestines. Moreover, we report the downregulation of PRDM5 protein expression in human colon neoplastic lesions. In summary, our data provide the first causal link between Prdm5 loss and intestinal carcinogenesis, and uncover an extensive and novel PRDM5 target repertoire likely facilitating the tumor-suppressive functions of PRDM5.
Beat-to-beat time series of systolic, diastolic, mean arterial pressure (SAP, DAP, MAP, respectively) and heart period (HP, a surrogate for RR intervals) were analyzed in time (mean, standard ...deviation) and frequency domain (power in low frequency band (LF, 0.004-0.15 Hz), total power (TP) and normalized LF power (LF% = LF/(TP-VLF), VLF are the very low frequencies 0-0.004 Hz)). Conclusions: Both the groups reached the target mean MAP of 65 mmHg, but the difference in the therapy response is evident: an activation of the sympathetic vasomotor control was shown only in R patients even if they received lower dosages of vasopressors and similar dosages of sedation. The higher fluid balance in NR, mostly at T1, could have affected the sympathetic tone, according to the hypothesis that central fluid accumulation affects the BR mediated sympathetic outflow. ...from BRS analysis we found that the baroreflex feedback gain increased at T2 in NR, whereas the feedforward mechanical gain decreased.
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