Data augmentation from RGB to chlorophyll fluorescence imaging Application to leaf segmentation of Arabidopsis thaliana from top view images

Résumé en françai

The measurement of photoneutron dose around an 18 MV Varian linear accelerator by TLD600 and TLD700 dosimeters inside the polyethylene sphere of neutron probe LB 6411

Bremsstrahlung X-rays from high-energy linear accelerators (Linacs) produce neutrons as a result ofphotonuclear reactions mainly with the different materials constituting the accelerator head. The neutronsproduced during high energy radiotherapy should be considered in terms of protection and ose escalation. Due to the very intense photon component in the Linac field causing pulse pile-up and dead-time effects indetectors, measurement of the corresponding neutron dose by active dosimeters is extremely troublesome. In this study, the neutron probe LB 6411, which active detector of 3He proportional counter tube was replaced withthe passive detectors of TLD600 and TLD700, has been used to perform neutron measurements at four pointsaround the 18 MV Varian 2100C Linac facility. The neutron dose equivalent at the distance of 1 and 2 m fromthe isocentre on the patient couch was obtained 2.2 and 0.75 mSv.Gy-1respectively. According to the results,the dose equivalent from emitted photoneutrons is not negligible and therefore treatment conditions should beoptimized. The results of this study emphasized that TLD600 and TLD700 dosimeters inside the polyethylenesphere of neutron probe LB 6411 is an appropriate choice for studying photoneutron production in the vicinity ofthe accelerato

Evaluation and comparison of dosimetric parameters in PTV for prostate cancer via step and shoot IMRT and 3DCRT

The aim of radiation therapy treatment planning is to achieve an optimal balance between delivering a high dose to target volume and a low dose to healthy tissues. The integral dose, conformity and homogeneity indexes, hence, are the important guidance for predicting the radiation effects and choosing the optimal treatment plan. The goal of this study is to compare and investigate the aforementioned parameters in 3DCRT vs. IMRT plan. In order to evaluate dosimetric parameters, data from five patients with prostate cancer, planned by IMRT and 3DCRT were obtained. Prescribed doses for IMRT procedure and 3DCRT were 80Gy and 70 Gy, respectively. Also, the target coverage was achieved with 95% of the prescribed dose to 95% of the PTV in 3DCRT and 95% of the prescribed dose to 98% of the PTV in IMRT method. A total of thirty IMRT and 3DCRT plans were performed for evaluation of dosimetric parameters (for each patient both treatment plans, step and shoot IMRT and 3DCRT with 6, 10 and 18MV energies) were done. The integral dose was calculated as the mean- dose times the volume of the structure. The mean integral dose (ID) received by rectum for 3DCRT was almost 1.01% greater than IMRT while in bladder mean value of ID for IMRT was approximately 1.68% higher than 3DCRT. For PTV in IMRT the ID of target volume had the biggest value (1.14%) compared to that of 3DCRT. Dose conformity in PTV volume in S.A.S and 3DCRT was almost equal. The same outcome was achieved in homogeneity index. The results of this study shows that IMRT method leads to adequate target dose coverage while the prescribed dose for this modality is higher than 3DCRT. IMRT has the ability of increasing the maximum dose to tumor region and improves conformity and homogeneity indexes in target volume and also reduces dose to OAR

Assessment of subclinical left ventricular dysfunction in patients with chronic mitral regurgitation using torsional parameters described by tissue doppler imaging

Background: Left ventricular (LV) twist is due to oppositely directed apical and basal rotation and has been proposed as a sensitive marker of LV function. We sought to assess the impact of chronic pure mitral regurgitation (MR) on the torsional mechanics of the left human ventricle using tissue Doppler imaging. Methods: Nineteen severe MR patients with a normal LV ejection fraction and 16 non-MR controls underwent conventional echocardiography and apical and basal short-axis color Doppler myocardial imaging (CDMI). LV rotation at the apical and basal short-axis levels was calculated from the averaged tangential velocities of the septal and lateral regions, corrected for the LV radius over time. LV twist was defined as the difference in LV rotation between the two levels, and the LV twist and twisting/untwisting rate profiles were analyzed throughout the cardiac cycle. Results: LV twist and LV torsion were significantly lower in the MR group than in the non-MR group (10.38 ° ± 4.04 ° vs. 13.95 ° ± 4.27 °; p value = 0.020; and 1.29 ± 0.54 °/cm vs. 1.76 ± 0.56 °/cm; p value = 0.021, respectively), both suggesting incipient LV dysfunction in the MR group. Similarly, the untwisting rate was lower in the MR group (-79.74 ± 35.97 °/s vs.-110.96 ± 34.65 °/s; p value = 0.020), but there was statistically no significant difference in the LV twist rate. Conclusion: The evaluation of LV torsional parameters in MR patients with a normal LV ejection fraction suggests the potential role of these sensitive variables in assessing the early signs of ventricular dysfunction in asymptomatic patients

Intracardiac metastasis of malignant melanoma

Aim: To report a case of intracardiac metastasis of malignant melanoma with multiple mobile, large masses in left atrium (LA), left ventricle (LV) and right atrium (RA). © The Author 2007

Pulmonary arterial pressure detects functional mitral stenosis after annuloplasty for primary mitral regurgitation: An exercise stress echocardiographic study

Introduction: The restrictive mitral valve annuloplasty (RMA) is the treatment of choice for degenerative mitral regurgitation (MR), but postoperative functional mitral stenosis remains a matter of debate. In this study, we sought to determine the impact of mitral stenosis on the functional capacity of patients. Methods: In a cross-sectional study, 32 patients with degenerative MR who underwent RMA using a complete ring were evaluated. All participants performed treadmill exercise test and underwent echocardiographic examinations before and after exercise. Results: The patients� mean age was 50.1 ± 12.5 years. After a mean follow-up of 14.1 ± 5.9 months (6�32 months), the number of patients with a mitral valve peak gradient >7.5 mm Hg, a mitral valve mean gradient >3 mm Hg, and a pulmonary arterial pressure (PAP) �25 mm Hg at rest were 50, 40.6, and 62.5, respectively. 13 patients (40.6) had incomplete treadmill exercise test. All hemodynamic parameters were higher at peak exercise compared with at rest levels (all P <.05). The PAP at rest and at peak exercise as well as peak transmitral gradient at peak exercise were higher in patients with incomplete exercise compared with complete exercise test (all P <.05). The PAP at rest (a sensitivity and a specificity of 84.6 and 52.6, respectively; area under the curve AUC =.755) and at peak exercise (a sensitivity and a specificity of 100% and 47.4%, respectively; AUC =.755) discriminated incomplete exercise test. Conclusion: The RMA for degenerative MR was associated with a functional stenosis and the PAP at rest and at peak exercise discriminated low exercise capacity. © 2017, Wiley Periodicals, Inc

Pulmonary arterial pressure detects functional mitral stenosis after annuloplasty for primary mitral regurgitation: An exercise stress echocardiographic study

Introduction: The restrictive mitral valve annuloplasty (RMA) is the treatment of choice for degenerative mitral regurgitation (MR), but postoperative functional mitral stenosis remains a matter of debate. In this study, we sought to determine the impact of mitral stenosis on the functional capacity of patients. Methods: In a cross-sectional study, 32 patients with degenerative MR who underwent RMA using a complete ring were evaluated. All participants performed treadmill exercise test and underwent echocardiographic examinations before and after exercise. Results: The patients� mean age was 50.1 ± 12.5 years. After a mean follow-up of 14.1 ± 5.9 months (6�32 months), the number of patients with a mitral valve peak gradient >7.5 mm Hg, a mitral valve mean gradient >3 mm Hg, and a pulmonary arterial pressure (PAP) �25 mm Hg at rest were 50, 40.6, and 62.5, respectively. 13 patients (40.6) had incomplete treadmill exercise test. All hemodynamic parameters were higher at peak exercise compared with at rest levels (all P <.05). The PAP at rest and at peak exercise as well as peak transmitral gradient at peak exercise were higher in patients with incomplete exercise compared with complete exercise test (all P <.05). The PAP at rest (a sensitivity and a specificity of 84.6 and 52.6, respectively; area under the curve AUC =.755) and at peak exercise (a sensitivity and a specificity of 100% and 47.4%, respectively; AUC =.755) discriminated incomplete exercise test. Conclusion: The RMA for degenerative MR was associated with a functional stenosis and the PAP at rest and at peak exercise discriminated low exercise capacity. © 2017, Wiley Periodicals, Inc

Developing Prediction Equations and a Mobile Phone Application to Identify Infants at Risk of Obesity

Background: Advancements in knowledge of obesity aetiology and mobile phone technology have created the opportunity to develop an electronic tool to predict an infant’s risk of childhood obesity. The study aims were to develop and validate equations for the prediction of childhood obesity and integrate them into a mobile phone application (App). Methods and Findings: Anthropometry and childhood obesity risk data were obtained for 1868 UK-born White or South Asian infants in the Born in Bradford cohort. Logistic regression was used to develop prediction equations (at 6±1.5, 9±1.5 and 12±1.5 months) for risk of childhood obesity (BMI at 2 years >91st centile and weight gain from 0–2 years >1 centile band) incorporating sex, birth weight, and weight gain as predictors. The discrimination accuracy of the equations was assessed by the area under the curve (AUC); internal validity by comparing area under the curve to those obtained in bootstrapped samples; and external validity by applying the equations to an external sample. An App was built to incorporate six final equations (two at each age, one of which included maternal BMI). The equations had good discrimination (AUCs 86–91%), with the addition of maternal BMI marginally improving prediction. The AUCs in the bootstrapped and external validation samples were similar to those obtained in the development sample. The App is user-friendly, requires a minimum amount of information, and provides a risk assessment of low, medium, or high accompanied by advice and website links to government recommendations. Conclusions: Prediction equations for risk of childhood obesity have been developed and incorporated into a novel App, thereby providing proof of concept that childhood obesity prediction research can be integrated with advancements in technology

Assessment of left atrial reservoir function in mitral valve disease by tissue doppler, strain and strain rate imaging

Introduction: Mitral valve stenosis and mitral valve regurgitation still result in significant morbidity and mortality. It has been shown that atrial remodeling and atrial fibrillation may occur in these patients. We sought to investigate how pressure or volume overload in the left atrium could impact atrial deformation properties obtained via Doppler-derived velocity and strain/strain rate imaging. Methods: Thirty-six patients, comprising 17 patients with a diagnosis of moderate to severe mitral stenosis and 19 patients with a diagnosis of moderate to severe mitral regurgitation, were compared with 16 healthy subjects. Two-dimensional, pulse Doppler, and tissue Doppler transthoracic echocardiographic study was performed. Measurement of regional velocity, strain and SR profiles, peak systolic velocity, peak strain, and strain rate was performed in two segments of the four left atrial walls. Results: There was a significant decline in peak systolic velocity in the mitral stenosis patients in both annular and roof segments, but the difference was not statistically significant between the mitral regurgitation patients and the healthy subjects. Total velocity was significantly lower in the mitral stenosis patients than in the healthy subjects, but the difference was not statistically significant between the healthy subjects and the mitral regurgitation patients. Comparison of total strain showed significant differences between the three groups mainly due to a decline in strain in the mitral stenosis patients in comparison with the other two groups. Comparison of total peak systolic strain rate between the groups showed significant differences due to a significant decline in the mitral stenosis group and a non-significant decline in the mitral regurgitation group by comparison with the healthy group. Conclusion: This reduction, especially in strain and strain rate, shows that the reservoir function of the left atrium could be compromised more severely in asymptomatic mitral stenosis patients. © 2014 American Scientific Publishers All rights reserved