THE IDENTIFICATION AND DIFFERENTIATION BETWEEN NORMAL AND SECONDARY COLORECTAL CANCER IN HUMAN LIVER TISSUE USING X-RAY INTERACTION TECHNIQUES

As secondary colorectal liver cancer is the most widespread malignancy in patients with colorectal cancer, the main aim of this study is to identify and differentiate between benign and malignant secondary colorectal liver cancer tissue. Low energy X-ray interaction techniques were used. XRF and coherent scattering data were collected for all 24 normal and 24 tumour matched pair tissues. Measurements of these parameters were made using a laboratory experimental set-up comprising a Mo X-ray tube, Si Drift detector and Scintillation (NaI) detector. Twelve elements of interest were statistically explored for normal and tumour samples. Comparing normal and tumour tissues, statistically significant differences have been determined for K, Ca, Cr, Fe, Cu, Zn, Br and Rb. However, for P, S, As and Se, no statistically significant differences have been found. Coherent scatter profiles were collected and fitted for all the samples and three peaks were observed at momentum transfer values: adipose peak: 1.1 nm-1, fibrous peak: 1.6 nm-1 and water content peak: 2.2 nm-1. The Amplitude, FWHM and area under these peaks were statistically analysed. These parameters were found to be significantly higher in secondary colorectal liver tumour compared to surrounding normal liver tissue for both fibrous and water content peaks. However, no significant differences were found for adipose peak parameters. Multivariate analysis was performed using the XRF, coherent scatter and elemental ratios data separately and the accuracy of classification results of 20 unknown samples was found. However when all the variables were combined together, the classification models were improved. This study has shown that the XRF and coherent scatter data of normal and secondary colorectal liver cancer are statistically different and the combination of these variables in multivariate analysis has the potential to be used as a method of distinguishing normal liver tissue from the malignant tumour tissue.Master of Science (MSc

Development of an Advanced 2D THGEM Microdosimetric Detector

The THick Gas Electron Multiplier (THGEM) based tissue-equivalent proportional counter (TEPC) has been proven to be useful for microdosimetry due to its flexibility in varying the gaseous sensitive volume and achieving high multiplication gain. Aiming at measuring the spatial distribution of radiation dose for mixed neutron-gamma fields, an advanced two-dimensional (2D) THGEM TEPC was designed and constructed at McMaster University which will enable us to overcome the operational limitation of the classical TEPCs, particularly for high dose rate fields. Compared to the traditional TEPCs, anode wire electrodes were replaced by THGEM layer, which not only enhances the gas multiplication gain but also offers a flexible and convenient fabrication or building 2D detectors. The 2D THGEM TEPC consists of an array of 3×3 sensitive volumes, equivalent to 9 individual TEPCs, each of which has a dimension of 5 mm diameter and length. Taking the overall cost, size and flexibility into account, to process 9 detectors signals simultaneously, a multi-input digital pulse processing system was developed by using modern microcontrollers, each of which is coupled to a 12-bit sampling ADC with a sampling rate of 42 Msps. The signal processing system was tested using a NaI(Tl) detector, which has proven that is it faster than a traditional analogue system and a commercial digital system. Using the McMaster Tandetron 7Li(p,n) accelerator neutron source, both fundamental detector performance, as well as neutron dosimetric response of the 2D THGEM TEPC, has been extensively investigated and compared to the data acquired by a spherical TEPC. It was shown that the microdosimetric response and the measured absorbed dose rate of the 2D THGEM detector developed in this study are comparable to the standard 1/2" TEPC which is commercially available.ThesisDoctor of Philosophy (PhD

The Mediating Role of Emotion Regulation Difficulties in the Relationship between Abuse Experiences and Body Image Dissatisfaction among Adolescent Girls

The purpose of this study was to examine the mediating role of emotion regulation difficulties in the relationship between abuse experiences and body image dissatisfaction in adolescent girls. The present study was an applied and correlational method based on structural equation modeling. The statistical population of this study was all female high school students in Tehran in the academic year 2019-2020. The sampling method of this study was a multistage cluster procedure. After distributing and collecting the questionnaires and removing the incomplete questionnaires, 218 subjects were finally analyzed. The data collection instruments were the Fisher Body Image Scale (FBIS), the Difficulties in Emotion Regulation Scale (DERS), and the Experience of Abuse Questionnaire (CAQ). Data were analyzed using Pearson correlation in Spss-24 software and path analysis in Amos-24 software. The results of the present study showed that there was a significant relationship between the experience of abuse and difficulties in emotion regulation and dissatisfaction with body image. In addition, there was a significant relationship between difficulties in emotion regulation and dissatisfaction with body image. Path analysis also revealed the mediating role of emotion regulation difficulties between abuse experience and body image dissatisfaction. Thus, the experience of child abuse causes body image dissatisfaction in adolescent girls by reinforcing difficulties in emotion regulation

Comprehensive characterization of ExacTrac stereoscopic image guidance system using Monte Carlo and Spektr simulations

Abstract The purpose of this work is to develop accurate computational methods to comprehensively characterize and model the clinical ExacTrac imaging system, which is used as an image guidance system for stereotactic treatment applications. The Spektr toolkit was utilized to simulate the spectral and imaging characterization of the system. Since Spektr only simulates the primary beam (ignoring scatter), a full model of ExacTrac was also developed in Monte Carlo (MC) to characterize the imaging system. To ensure proper performance of both simulation models, Spektr and MC data were compared to the measured spectral and half value layers (HVLs) values. To validate the simulation results, x-ray spectra of the ExacTrac system were measured for various tube potentials using a CdTe spectrometer with multiple added narrow collimators. The raw spectra were calibrated using a 57Co source and corrected for the escape peaks and detector efficiency. HVLs in mm of Al for various energies were measured using a calibrated RaySafe detector. Spektr and MC HVLs were calculated and compared to the measured values. The patient surface dose was calculated for different clinical imaging protocols from the measured air kerma and HVL values following the TG-61 methodology. The x-ray focal spot was measured by slanted edge technique using gafchromic films. ExacTrac imaging system beam profiles were simulated for various energies by MC simulation and the results were benchmarked by experimentally acquired beam profiles using gafchromic films. The effect of 6D IGRT treatment couch on beam hardening, dynamic range of the flat panel detector and scatter effect were determined using both Spektr simulation and experimental measurements. The measured and simulated spectra (of both MC and Spektr) for various kVps were compared and agreed within acceptable error. As another validation, the measured HVLs agreed with the Spektr and MC simulated HVLs on average within 1.0% for all kVps. The maximum and minimum patient surface doses were found to be 1.06 mGy for shoulder (high) and 0.051 mGy for cranial (low) imaging protocols, respectively. The MC simulated beam profiles were well matched with experimental results and replicated the penumbral slopes, the heel effect, and out-of-field regions. Dynamic range of detector (in terms of air kerma at detector surface) was found to be in the range of [6.1 × 10−6, 5.3 × 10−3] mGy. Accurate MC and Spektr models of the ExacTrac image guidance system were successfully developed and benchmarked via experimental validation. While patient surface dose for available imaging protocols were reported in this study, the established MC model may be used to obtain 3D imaging dose distribution for real patient geometries.</jats:p

The Mediating Role of Positive and Negative Affect in the Association of Perceptions of Parenting Styles with Resilience among Adolescents with Addicted Parents

Objective: This study aimed to investigate the mediating role of positive and negative affect in the association of perceptions of parental involvement, autonomy support, and warmth with resilience among Adolescents with Addicted Parents.&#x0D; Method: In this descriptive-correlational study, 63 Adolescents of Addicted Parents studying in Zahak and Hirman, located in Sistan and Baluchestan Province in Iran, were selected using convenience sampling method. The participants completed the questionnaires on perceptions of parenting styles, resilience, and positive and negative affect. Data were analyzed via the correlation coefficient and path analysis.&#x0D; Results: The results showed that the adolescents’ perceived parenting styles were directly and significantly related to positive affect and resilience (P &lt; 0.01). Moreover, the results of the path analysis indicated that mediated by positive affect, the adolescents’ perceived parenting styles predicted resilience indirectly (P &lt; 0.01).&#x0D; Conclusion: Given the results of this study, perceived parenting styles can directly and indirectly predict resilience. It can be concluded that adolescents’ perceived parenting styles can enhance resilience among them through promoting positive affect.</jats:p