A portable primary-standard level graphite calorimeter for absolute dosimetry in clinical pencil beam scanning proton beams

Objective. To report the use of a portable primary standard level graphite calorimeter for direct dose determination in clinical pencil beam scanning proton beams, which forms part of the recommendations of the proposed Institute of Physics and Engineering in Medicine (IPEM) Code of Practice (CoP) for proton therapy dosimetry.Approach. The primary standard proton calorimeter (PSPC) was developed at the National Physical Laboratory (NPL) and measurements were performed at four clinical proton therapy facilities that use pencil beam scanning for beam delivery. Correction factors for the presence of impurities and vacuum gaps were calculated and applied, as well as dose conversion factors to obtain dose to water. Measurements were performed in the middle of 10 × 10 × 10 cm3homogeneous dose volumes, centred at 10.0, 15.0 and 25.0 g·cm-2depth in water. The absorbed dose to water determined with the calorimeter was compared to the dose obtained using PTW Roos-type ionisation chambers calibrated in terms of absorbed dose to water in60Co applying the recommendations in the IAEA TRS-398 CoP.Main results.The relative dose difference between the two protocols varied between 0.4% and 2.1% depending on the facility. The reported overall uncertainty in the determination of absorbed dose to water using the calorimeter is 0.9% (k= 1), which corresponds to a significant reduction of uncertainty in comparison with the TRS-398 CoP (currently with an uncertainty equal or larger than 2.0% (k= 1) for proton beams).Significance. The establishment of a purpose-built primary standard and associated CoP will considerably reduce the uncertainty of the absorbed dose to water determination and ensure improved accuracy and consistency in the dose delivered to patients treated with proton therapy and bring proton reference dosimetry uncertainty in line with megavoltage photon radiotherapy.

What It Takes to Solve the Hubble Tension through Modifications of Cosmological Recombination

We construct data-driven solutions to the Hubble tension which are perturbative modifications to the fiducial ΛCDM cosmology, using the Fisher bias formalism. Taking as proof of principle the case of a time-varying electron mass and fine structure constant, and focusing first on Planck CMB data, we demonstrate that a modified recombination can solve the Hubble tension and lower S_{8} to match weak lensing measurements. Once baryonic acoustic oscillation and uncalibrated supernovae data are included, however, it is not possible to fully solve the tension with perturbative modifications to recombination.

Alanine response to low energy synchrotron x-ray radiation

Objective. The radiation response of alanine is very well characterized in the MV photon energy range where it can be used to determine the dose delivered with an accuracy better than 1%, making it suitable as a secondary standard detector in cancer radiation therapy. This is not the case in the very low energy keV x-ray range where the alanine response is affected by large uncertainties and is strongly dependent on the x-ray beam energy. This motivated the study undertaken here.Approach. Alanine pellets with a nominal thickness of 0.5 mm and diameter of 5 mm were irradiated with monoenergetic x-rays at the Diamond Light Source synchrotron, to quantify their response in the 8-20 keV range relative to60Co radiation. The absorbed dose to graphite was measured with a small portable graphite calorimeter, and the DOSRZnrc code in the EGSnrc Monte Carlo package was used to calculate conversion factors between the measured dose to graphite and the absorbed dose to water delivered to the alanine pellets. GafChromic EBT3 films were used to measure the beam profile for modelling in the MC simulations.Main results. The relative responses measured in this energy range were found to range from 0.616 to 0.643, with a combined relative expanded uncertainty of 3.4%-3.5% (k= 2), where the majority of the uncertainty originated from the uncertainty in the alanine readout, due to the small size of the pellets used.Significance. The measured values were in good agreement with previously published data in the overlapping region of x-ray energies, while this work extended the dataset to lower energies. By measuring the response to monoenergetic x-rays, the response to a more complex broad-spectrum x-ray source can be inferred if the spectrum is known, meaning that this work supports the establishment of alanine as a secondary standard dosimeter for low-energy x-ray sources.

The role of PLiM technologies in CANDU TM ongoing aging management, life extension, and new designs

This paper will discuss AECL’s approach in providing a comprehensive “full knowledge” support to plant ageing and ageing management. This requires the integration of research and development into safety, design, and service areas of the company. The paper will also explore how this integration is being accomplished through the initiatives of the PLiM program. The paper will examine several examples of how AECL is developing its understanding of ageing degradation, the engineered solutions, applying those solutions, improving those solutions, and finally incorporating these solutions into both the PLiM program and into new designs.

The swelling behavior of the mouse cervix: Changing kinetics with osmolarity and the role of hyaluronan in pregnancy

The cervical remodeling process during pregnancy is characterized by progressive compositional and structural changes in the tissues extra-cellular matrix (ECM). Appropriately timed remodeling is critical for healthy gestation and prevention of premature cervical softening leading to preterm birth (PTB). Modification of the ECM glycosaminoglycans (GAGs) content with advancing pregnancy, especially the non-sulfated GAG hyaluronan (HA), is a fundamental change associated with cervical remodeling. While GAGs have numerous physiological roles, the mechanical consequence of evolving GAG content on cervical structure-function behavior remains an open question. Additionally, an understanding of cervical swelling properties, postulated to be regulated in part by GAGs, is required for the appropriate definition of a reference configuration for mechanical tests and to enhance biological understanding. To investigate cervical swelling, osmotic loading tests are conducted on isolated wild type mouse cervices throughout pregnancy. These tests are performed in various osmolarity solutions to assess the influence of the media on swelling kinetics. A genetically altered strain of mice with depletion of cervical HA is also tested to elucidate the contribution of HA to tissue swelling. Results show ex vivo cervical swelling is significant with volume changes ranging from 20 to 100% after 3h of free swelling. The swelling kinetics depend highly on osmolarity of the media and is altered with advancing pregnancy. The contribution of HA to swelling is only significant in hypo-osmotic solution when HA cervical content is high at the end of pregnancy. In summary, it is critical to account for swelling deformation mechanisms after excision in mechanical experiments. STATEMENT OF SIGNIFICANCE: The cervical extracellular matrix (ECM) undergoes drastic changes to fulfill the functional change of the cervix during pregnancy. Inappropriate timing for this transformation can result in preterm birth, a severe clinical challenge. One of the fundamental changes of the cervical ECM is the significant modification of the glycosaminoglycan content, especially hyaluronan (HA), which is thought to contribute significantly to the swelling and mechanical properties of the cervix. This study aims to measure the swelling kinetics of cervical tissue during pregnancy and to investigate the role of HA in these swelling tendencies. Results show the significant swelling of cervical tissue, which evolves as pregnancy progresses, highlighting a key material property feature of the remodeled cervix. Using a mouse strain with a cervical HA depletion, this work shows HA contributes to the swelling trends of late-term cervical tissue, in a hypo-osmotic solution.

Host inflammatory response is the major marker of severe respiratory syncytial virus infection in older adults

OBJECTIVES

We aim to study the viral kinetics and host inflammatory response of RSV infection in older adults, and their correlation with disease severity.

METHODS

We performed a prospective observational study in adults with RSV infection. We serially collected nasal-throat swabs for quantification of RSV-A and RSV-B viral load, and peripheral blood samples for measurement of cytokine/chemokine concentrations. The study endpoints were (i) requiring supplemental oxygen therapy, and (ii) non-invasive ventilation, intensive care, or died within 30 days of admission. We performed multivariable logistic regression models to identify independent variables for severe disease.

RESULTS

We enrolled 71 hospitalized patients and 10 outpatients treated for RSV infection (median age 75 years, 51% male, and 74% with comorbidities). Among hospitalized patients, 61% required supplemental oxygen therapy, and 18% had severe disease requiring non-invasive ventilation or intensive care, or died within 30 days. Inflammatory cytokine/chemokines IL-6, CXCL8/IL-8, CXCL9/MIG and CXCL10/IP-10 increased significantly during the acute phase of illness. IL-6 concentration was independently associated with severe disease after adjusting for confounding factors. RSV viral load was not associated with disease severity throughout the course of illness.

CONCLUSION

Host inflammatory response is a major marker of severe disease in older adults with RSV infection.

MicroRNAs as biomarkers of atrophic scarring in acne: a cross-sectional analysis of 41 patients

BACKGROUND

Acne is the commonest inflammatory dermatosis seen worldwide. Atrophic acne scarring is a frequent complication, which can arise from acne of any severity. Micro (mi)RNAs are noncoding RNA molecules of 19-25 nucleotides that function as post-transcriptomic mediators of gene expression. They have demonstrated differential expression in various pathologies, such as eczema and psoriasis, allowing for a unique miRNA 'signature' profile to be established for different disease states.

AIM

To establish a miRNA signature for acne, and acne-associated atrophic scarring and to identify if a pattern of circulating miRNA is evident in patients who are prone to scarring.

METHODS

In total, 41 participants were consecutively recruited to this study. Circulating miRNA was quantified from plasma samples in all 41 patients, while in 8 patients, and in a further validation cohort of 9 patients, whole miRNAome was undertaken from tissue specimens, which included lesional, normal and where present, scarred skin.

RESULTS

Three miRNAs, miR-223, miR-21 and miR-150, were statistically significantly overexpressed in acne lesions, and notably, in clinically uninvolved skin in participants prone to scarring. In this subgroup, we also found statistically significantly elevated levels of circulating miRNA-21 and miRNA-150.

CONCLUSION

The presence of elevated levels of these specific miRNAs in the serum of patients with acne raises the potential of a blood test to identify those at risk of scarring, allowing for earlier intervention with effective therapy.

The change of serum serotonin levels between acute coronary syndrome and chronic stable angina undergoing percutaneous coronary intervention

Background

Activated platelets release serotonin (5-hydroxytryptamine, 5HT) causing vasoconstriction and aggregation of platelets in patients with acute coronary syndrome (ACS). It can lead to undergo percutaneous coronary intervention (PCI). We investigated the serial changes of serotonin level in patients with ACS and chronic stable angina (CSA) treated with PCI.

Methods

From July 2009 to April 2010, 123 consecutive patients who have undergone PCI for either ACS (n=63) or CSA (n=60) were enrolled. After the loading dose of aspirin 300mg and clopidogrel 600mg before PCI, maintenance once daily dose of 100mg and 75mg have been given from the day after PCI in all patients. Serum serotonin level (SERO) were serially measured at baseline, pre-, post-PCI, 90 min, 6 hours, 12 hours, 24 hours and 48 hours to compare between ACS and CSA groups. All demographic, biochemical variables, and clinical events were also collected for comparison in each group.

Results

SERO at post-PCI (55.2±120.0 vs 20.1±24.0, p=0.03) and peak level (94.0±170.9 vs 38.8±72.3, p=0.02) were significantly higher in ACS group. SERO after 90 min (34.4±66.1 vs 28.7±38.2, p=0.8), 6 hours (23.9±38.3 vs 10.1±10.0, p=0.34), 24 hours (55.8±108.5 vs 37.2±88.2, p=0.39) and 48 hours (43.5±122.9 vs 25.2±65.5, p=0.53) tended to be higher in ACS group than CSA group without statistical significance. SERO rebounded at 24 hours post-PCI and dropped at 48 hours.

Conclusions

SERO was more elevated in patients with ACS than those with CSA undergoing PCI, suggesting the need for more potent and sustained platelet inhibition particularly in ACS patients. SERO might be considered as a substitute marker of platelet activation. Triple antiplatelet therapy including selective serotonin receptor antagonist on top of aspirin and clopidogrel could be as an option for ACS patients undergoing PCI

Funding Acknowledgement

Type of funding source: Other. Main funding source(s): Hallym University Research Fund 2017 (HURF-2017-84)

Comparison of prasugrel and ticagrelor for patient with acute coronary syndrome: a systematic review and meta-analysis

Background

Prasugrel and ticagrelor are both effective anti-platelet drugs for patients with acute coronary syndrome. However, there has been limited data on the direct comparison of prasugrel and ticagrelor until the recent ISAR-REACT 5 trial.

Purpose

To compare the efficacy of prasugrel and ticagrelor in patients with acute coronary syndrome with respect to the primary composite endpoint of myocardial infarction (MI), stroke or cardiac cardiovascular death, and secondary endpoints including MI, stroke, cardiovascular death, major bleeding (Bleeding Academic Research Consortium (BARC) type 2 or above), and stent thrombosis within 1 year.

Methods

Meta-analysis was performed on randomised controlled trials (RCT) up to December 2019 that randomised patients with acute coronary syndrome to either prasugrel or ticagrelor. RCTs were identified from Medline, Embase and ClinicalTrials.gov using Cochrane library CENTRAL by 2 independent reviewers with “prasugrel” and “ticagrelor” as search terms. Effect estimates with confidence intervals were generated using the random effects model by extracting outcome data from the RCTs to compare the primary and secondary clinical outcomes. Cochrane risk-of-bias tool for randomised trials (Ver 2.0) was used for assessment of all eligible RCTs.

Results

411 reports were screened, and we identified 11 eligible RCTs with 6098 patients randomised to prasugrel (n=3050) or ticagrelor (n=3048). The included trials had a follow up period ranging from 1 day to 1 year. 330 events on the prasugrel arm and 408 events on the ticagrelor arm were recorded. There were some concerns over the integrity of allocation concealment over 7 trials otherwise risk of other bias was minimal. Patients had a mean age of 61±4 (76% male; 50% with ST elevation MI; 35% with non-ST elevation MI; 15% with unstable angina; 25% with diabetes mellitus; 64% with hypertension; 51% with hyperlipidaemia; 42% smokers). There was no significant difference in risk between the prasugrel group and the ticagrelor group on the primary composite endpoint (Figure 1) (Risk Ratio (RR)=1.17; 95% CI=0.97–1.41; p=0.10, I2=0%). There was no significant difference between the use of prasugrel and ticagrelor with respect to MI (RR=1.24; 95% CI=0.81–1.90; p=0.31); stroke (RR=1.05; 95% CI=0.66–1.67; p=0.84); cardiovascular death (RR=1.01; 95% CI=0.75–1.36; p=0.95); BARC type 2 or above bleeding (RR=1.17; 95% CI =0.90–1.54; p=0.24); stent thrombosis (RR=1.58; 95% CI =0.90–2.76; p=0.11).

Conclusion

Compared with ticagrelor, prasugrel did not reduce the primary composite endpoint of MI, stroke and cardiovascular death within 1 year. There was also no significant difference in the risk of MI, stroke, cardiovascular death, major bleeding and stent thrombosis respectively.

Figure 1. Primary Objective

Funding Acknowledgement

Type of funding source: None

Effects of comorbidities on quality of life in Filipino people with tuberculosis

BACKGROUND: We investigated health-related quality of life (HrQoL) in Filipino people undergoing TB treatment, and whether HrQoL was negatively impacted by comorbidity with undernutrition, diabetes (DM) and anaemia.METHODS: Adult participants were enrolled in public facilities in Metro Manila (three sites) and Negros Occidental (two sites). Multivariate linear regression was used to model the four correlated domain scores from a WHOQOL-BREF questionnaire (physical, psychological, social, environmental). A forward-stepwise approach was used to select a final multivariable model with inclusion based on global tests of significance at P < 0.1.RESULTS: In 446 people on drug-susceptible TB treatment, DM and moderate/severe anaemia were not associated with HrQoL. After adjustment for age, sex, education, food insecurity, treatment adherence, inflammation, Category I or II TB treatment, treatment phase, current side effects and inhibited ability to work, moderate/severe undernutrition (body mass index < 17 kg/m²) was associated with lower HrQoL (P = 0.003) with reduced psychological (coefficient: -1.02, 95% CI -1.54 to -0.51), physical (-0.62, 95% CI -1.14 to -0.09) and environmental domain scores (-0.45, 95% CI -0.88 to -0.01). In 225 patients with known HIV status in Metro Manila, HIV was associated with modestly reduced HrQoL (P = 0.014).CONCLUSION: Nutritional status and food insecurity represent modifiable risk factors for poor HrQoL that may be alleviated through interventions.

Identification and validation of novel microenvironment-based immune molecular subgroups of head and neck squamous cell carcinoma: implications for immunotherapy

Background

Targeting the immune checkpoint pathway has demonstrated antitumor cytotoxicity in treatment-refractory head and neck squamous cell carcinoma (HNSC). To understand the molecular mechanisms underpinning its antitumor response, we characterized the immune landscape of HNSC by their tumor and stromal compartments to identify novel immune molecular subgroups.

Patients and methods

A training cohort of 522 HNSC samples from the Cancer Genome Atlas profiled by RNA sequencing was analyzed. We separated gene expression patterns from tumor, stromal, and immune cell gene using a non-negative matrix factorization algorithm. We correlated the expression patterns with a set of immune-related gene signatures, potential immune biomarkers, and clinicopathological features. Six independent datasets containing 838 HNSC samples were used for validation.

Results

Approximately 40% of HNSCs in the cohort (211/522) were identified to show enriched inflammatory response, enhanced cytolytic activity, and active interferon-γ signaling (all, P < 0.001). We named this new molecular class of tumors the Immune Class. Then we found it contained two distinct microenvironment-based subtypes, characterized by markers of active or exhausted immune response. The Exhausted Immune Class was characterized by enrichment of activated stroma and anti-inflammatory M2 macrophage signatures, WNT/transforming growth factor-β signaling pathway activation and poor survival (all, P < 0.05). An enriched proinflammatory M1 macrophage signature, enhanced cytolytic activity, abundant tumor-infiltrating lymphocytes, high human papillomavirus (HPV) infection, and favorable prognosis were associated with Active Immune Class (all, P < 0.05). The robustness of these immune molecular subgroups was verified in the validation cohorts, and Active Immune Class showed potential response to programmed cell death-1 blockade (P = 0.01).

Conclusions

This study revealed a novel Immune Class in HNSC; two subclasses characterized by active or exhausted immune responses were also identified. These findings provide new insights into tailoring immunotherapeutic strategies for different HNSC subgroups.

Investigation of a Novel Decision Support Metric for Head and Neck Adaptive Radiation Therapy Using a Real-Time In Vivo Portal Dosimetry System

In adaptive radiation therapy of head and neck cancer, any significant anatomical changes observed are used to adapt the treatment plan to maintain target coverage without elevating the risk of xerostomia. However, the additional resources required for adaptive radiation therapy pose a challenge for broad-based implementation. It is hypothesized that a change in transit fluence is associated with volumetric change in the vicinity of the target and therefore can be used as a decision support metric for adaptive radiation therapy. This was evaluated by comparing the fluence with volumetric changes in 12 patients. Transit fluence was measured by an in vivo portal dosimetry system. Weekly cone beam computed tomography was used to determine volume change in the rectangular region of interest from condyloid process to C6. The integrated transit fluence through the region of interest on the day of the cone beam computed tomography scan was calculated with the first treatment as the baseline. The correlation between fluence change and volume change was determined. A logistic regression model was also used to associate the 5% region of interest volume reduction replanning trigger point and the fluence change. The model was assessed by a chi-square test. The area under the receiver-operating characteristic curve was also determined. A total of 46 pairs of measurements were obtained. The correlation between fluence and volumetric changes was found to be -0.776 (P value <.001). The negative correlation is attributed to the increase in the photon fluence transport resulting from the volume reduction. The chi-square of the logistic regression was found to be 17.4 (P value <.001). The area under the receiver-operating characteristic curve was found to be 0.88. Results indicate the change in transit fluence, which can be measured without consuming clinical resources or requiring additional time in the treatment room, can be used as a decision support metric for adaptive therapy.