The purpose of this project was to develop a delivery system optimized for laser interstitial thermotherapy of small tumors of the breast. The proposed approach is to combine laser interstitial thermotherapy with stereotactic imaging for fiber guidance and treatment monitoring. The goals of the dissertation were to design a fiber insertion system for cylindrical diffusing tip optical fibers and to derive optimal laser parameters for coagulation of 1 cm tumor plus a surrounding 1 cm thick rim of healthy tissue. A fiber insertion system compatible with a high resolution stereotactic digital X-ray biopsy system was designed to guide the fiber into the tumor site in similar fashion to the insertion of the biopsy needle. An optical-thermal model consisting of a radiation model, a thermal model, and a coagulation model was developed and validated using ex-vivo porcine tissue. A single integrating sphere optical property measurement system and an inverse Monte Carlo algorithm were developed to measure the optical properties of ex-vivo porcine tissue at 830, 940, and 980 nm. An experimental method was developed to determine the parameters of the Arrhenius model (frequency factor (A) and activation energy (Ea)). The optical-thermal model was validated by comparing the predicted temperature and coagulation to results of laser irradiation experiments at 830, 940, and 980 nm. Using published values of the optical properties of the breast, the model predicts that a 3 cm coagulation size can be produced without vaporization in 10 min with 10.4 W at 980 and 940 nm and 13.2 W at 830 nm. The same outcome can be achieved in 20 min with 4.5 W at 980 and 940 nm and 6.1 W at 830 nm.

Interstitial laser thermal therapy is a novel local approach to treating prostate cancer. During treatment, thermal ablation may occur on the adjacent rectal wall. The aim of this thesis was therefore twofold: to study the effects of rectal cooling on lesion formation, and secondly, to engineer a computer controlled rectal cooling unit. To study the effects of the coolant temperatures and flow rate, thermal simulations were executed, followed by testing the phenomenon using agar gel phantoms which thermally mimic prostate tissue. Further simulations were run using a treatment planning software, which predicted the required coolant temperatures to protect the outer rectal wall while subsequently determining the shape and size of the resulting coagulated lesion at various laser settings. Results suggest that low coolant temperatures and low flow rates cause maximum cooling rates. Furthermore, the shape and size of the coagulated region is affected by coolant temperatures at specific laser powers and positions within the prostate.

Interstitial laser thermal therapy is a novel local approach to treating prostate cancer. During treatment, thermal ablation may occur on the adjacent rectal wall. The aim of this thesis was therefore twofold: to study the effects of rectal cooling on lesion formation, and secondly, to engineer a computer controlled rectal cooling unit. To study the effects of the coolant temperatures and flow rate, thermal simulations were executed, followed by testing the phenomenon using agar gel phantoms which thermally mimic prostate tissue. Further simulations were run using a treatment planning software, which predicted the required coolant temperatures to protect the outer rectal wall while subsequently determining the shape and size of the resulting coagulated lesion at various laser settings. Results suggest that low coolant temperatures and low flow rates cause maximum cooling rates. Furthermore, the shape and size of the coagulated region is affected by coolant temperatures at specific laser powers and positions within the prostate.

Purpose: To develop a lightweight, safe, and controllable electrical heating vest for heart failure and/or hypertension patients. Methods: a. A literature review related to the topic was conducted. b. A model of a simplified human body thermoregulation system was developed and simulated. It was used to predict the power requirement of the battery to increase core body temperature up to 1 Celsius degree (°C). c. A prototype with a smart controller was developed d. In-vitro tests of the prototype were conducted to assess performance and safety. e. The prototype was tested on 10 healthy human volunteers and the results were analyzed. Results: a. An average core body temperature increase of 0.3 °C (P<0.05) was observed in healthy human volunteer tests within 30 minutes. b. The vest induced decreases in systolic blood pressure of 5.5 mmHg and diastolic blood pressure of 4.8 mmHg on average. Conclusions: A carbon-fiber vest can increase body core temperature by 0.3°C lowering systolic and diastolic blood pressure, which can be potentially used for helping heart failure and/or hypertension patients.

Master of Science / Department of Electrical and Computer Engineering / Punit Prakash / Thermal therapies employing interstitial microwave applicators for hyperthermia or ablation are in clinical use for treatment of cancer and benign disease in various organs. However, treatment of targets in proximity to critical structures with currently available devices is risky due to unfocused deposition of energy into tissue. For successful treatment, complete thermal coverage of the tumor and margin of surrounding healthy tissue must be achieved, while precluding damage to critical structures. This thesis investigates two approaches to increase precision of microwave thermal therapy. Chapter 2 investigates a novel coaxial antenna design for microwave ablation (MWA) employing a hemi-cylinderical reflector to achieve a directional heating pattern. A proof of concept antenna with an S₁₁ of -29 dB at 2.45 GHz was used in ex vivo experiments to characterize the antennas’ heating pattern with varying input power and geometry of the reflector. Ablation zones up to 20 mm radially were observed in the forward direction, with minimal heating (less than 4 mm) behind the reflector. Chapter 3 investigates the use of magnetic nanoparticles (MNP) of varying size and geometry for enhancing microwave tissue heating. A conventional dipole, operating at 2.45 GHz and radiating 15 W, was inserted into a 20 mm radius sphere of distributed MNPs and heating measurements were taken 5 mm, 10 mm, and 15 mm radially away. A heating rate of 0.08°C/s was observed at 10 mm, an increase of 2-4 times that of the control measurement. These approaches provide strong potential for improving spatial control of tissue heating with interstitial and catheter-based microwave antennas.

Polycystic Ovary Syndrome (PCOS) is a complex endocrine disorder that increases a woman’s risk of developing cardiovascular disease and diabetes. Women with PCOS have extremely high rates of obesity, insulin resistance, cardiovascular morbidity and mortality. Obese women with PCOS also tend to have elevated sympathetic nerve activity and systemic markers of inflammation, which likely contribute to cardiometabolic risk and PCOS pathogenesis. While few medication or lifestyle intervention options for women with PCOS target elevated sympathetic nerve activity, inflammation, and insulin resistance, passive heat exposure shows promise as a novel intervention for improving cardiovascular and metabolic health in this population. Therefore, the purpose of this study was to examine changes in inflammation, cardiovascular, autonomic, and metabolic health in obese women with PCOS following a 30-session, 8-10 week chronic passive heat intervention (termed ‘heat therapy’). Eighteen obese women with PCOS (Age: 27±1y, BMI 41.3±1.1 kg·m2) were matched for age and body mass index (BMI), then divided into heat therapy (HT) or time control (CON). At the beginning (Pre), middle (Mid), and end (Post) of 8-10 weeks, subjects participated in study days to assess vascular, autonomic, and metabolic function, and additionally underwent a subcutaneous fat biopsy in Pre and Post. HT subjects took part in 30 one-hour hot tub sessions over 8-10 weeks (3-4 per week) in 40.5˚C water, while CON subjects completed all other testing but were not exposed to heat. No change in BMI was observed over the study in HT or CON; however; HT subjects exhibited dramatically improved vascular and metabolic function, as well as reduced sympathetic nerve activity and circulating inflammatory markers. In fat biopsies, insulin signaling was improved in HT subjects, while CON subjects remained stable over time. These findings show promise for HT as a treatment option for obese women with PCOS to improve cardiovascular and metabolic risk profiles. This dissertation includes previously published co-authored material.

Master of Science / Department of Electrical and Computer Engineering / Punit Prakash / Microwave ablation (MWA) is a minimally invasive thermal therapy predominantly used in the treatment of localized cancer. Previous studies have demonstrated clinical use of MWA for treating lung tumors, however, these procedures have relied upon the use of rigid percutaneous MWA applicators which can limit the range of accessible tumors and may have inherent disadvantages for use in lung tissue. The objective of this work was to develop and characterize a bronchoscopic MWA applicator suitable for use in a system that enables bronchoscopic transparencymal nodule access (BTPNA). A 3D coupled FEM electromagnetic-heat transfer model was implemented to optimize the antenna design and evaluate the expected ablation size and shape. A prototype device was fabricated and experimentally evaluated in ex vivo tissue to verify simulation results and demonstrate proof-of-concept. Simulated and experimental results indicate the proposed device could create ablation zones 19.3 – 31.0 mm in diameter with 30 – 45 W of power applied for 5 – 10 minutes. Future bronchoscopic MWA applicators based on the design proposed in this study could allow physicians an even less invasive treatment option for lung cancer with increased accuracy and efficacy and reduced risk of procedural complications immediately following a positive bronchoscopic lung biopsy.

No description available.

PURPOSE: Thermal ablation therapy is an emerging local cancer treatment to destroy cancer tissue using heat. However variations in blood flow and energy absorption rates make it extremely challenging to monitor thermal changes. Insufficient ablation may lead to recurrence of the cancer while excessive ablation may damage adjacent healthy tissues. Ultrasound could be a convenient and inexpensive imaging modality for real-time monitoring of the ablation. For the development and optimization of these methods, it is essential to have ground truth data and a reliable and quantitative validation technique before beginning clinical trials on humans. In this dissertation, my primary focus was to solve the image-to-physical space registration problem using stereotactic fiducials that provide accurate correlation of ultrasound and pathology (ground truth) images. METHOD: A previously developed validation test-bed prototype was evaluated using phantom experiments to identify the shortcomings and limitations. In order to develop an improved validation platform, a simulator was implemented for evaluating registration methods as well as different line fiducial structures. New fiducial line structures were proposed, and new methods were implemented to overcome the limitations of the old system. The new methods were then tested using simulation results and phantom studies. Phantom experiments were conducted to improve the visibility of fiducials, as well as the quality of acquired ultrasound and pathology image datasets. RESULTS: The new system outperforms the previous one in terms of accuracy, robustness, and simplicity. The new registration method is robust to missing fiducials. I also achieved complete fiducial visibility in all images. Enhancing the tissue fixation medium improved the ultrasound data quality. The quality of pathology images were improved by a new imaging method. Simulation results show improvement in pose recovery accuracy using my proposed fiducial structure. This was validated by phantom studies reducing spatial misalignment between the US and pathology image sets. CONCLUSION: A new generation of test-bed was developed that provides a reliable and quantitative validation technique for evaluating and optimizing ablation monitoring methods. / Thesis (Master, Computing) -- Queen's University, 2011-09-29 20:31:55.159

Fundamento: medidas adjuvantes têm sido propostas para o tratamento de pacientes com insuficiência cardíaca, algumas não farmacológicas, como o uso do calor. Apesar dos resultados positivos para pacientes clinicamente estáveis, não existem trabalhos relacionados ao tratamento com calor na fase descompensada da insuficiência cardíaca em pacientes em uso de drogas vasoativas. Objetivos: avaliar os efeitos hemodinâmicos agudos do calor aplicado através da manta térmica em pacientes com insuficiência cardíaca descompensada (ICD) refratária. Para isso foi estabelecido como desfechos o aumento do índice cardíaco e a redução da resistência vascular sistêmica no primeiro dia de seguimento. Como objetivo secundário, avaliar se sessões repetidas de calor por cinco dias consecutivos promoveria ou sustentaria os efeitos hemodinâmicos obtidos agudamente e, se reduziria os níveis de BNP ao longo do seguimento. Métodos: ensaio clínico randomizado aberto, prospectivo, com grupo controle em pacientes portadores de ICD. O estudo foi dividido em duas fases. Na primeira fase foram estudados pacientes em um único dia e foi avaliado o efeito agudo do calor antes e após a intervenção. Na segunda fase o calor foi avaliado através de sessões diárias por cinco dias consecutivos. Foi utilizada a manta térmica por radiação infravermelha para o aquecimento dos pacientes. As medidas hemodinâmicas foram avaliadas por método invasivo através do cateter de Swan-Ganz e de maneira não invasiva pelo método de modelflow. Os pacientes estavam em uso de inotrópico endovenoso contínuo, no perfil hemodinâmico C segundo a classificação clínico-hemodinâmica de Stevenson e foram considerados refratários após tentativa de retirada da droga vasoativa sem sucesso. A população do estudo foi dividida em 2 grupos: grupo T (termoterapia) e grupo C (controle). O grupo T foi submetido à vasodilatação térmica através da manta térmica na temperatura de 50°C por 40 minutos adicionalmente ao tratamento medicamentoso. Os pacientes do grupo C mantiveram o tratamento medicamentoso e a manta térmica foi posicionada da mesma maneira por 40 minutos, porém desligada. Análise estatística: as variáveis foram analisadas pelo teste exato de Fisher ou razão de verossimilhança. A normalidade foi avaliada com o teste de Komogorov-Smirnov. As variáveis quantitativas foram apresentadas por média e desvio padrão. As médias foram avaliadas com análise de variância para medidas repetidas (ANOVA). Quando significante, utilizou-se contrastes para discriminar as diferenças entre os momentos. As medidas avaliadas em um único momento foram comparadas com teste t-Student. Foi utilizado o coeficiente de correlação de Pearson para a análise da correlação entre as medidas. Foram considerados estatisticamente significantes os valores de p < 0,05. Resultados: entre outubro de 2007 e abril de 2013, 165 pacientes foram avaliados para possível elegibilidade. Destes, 12 pacientes recusaram participar do estudo e 105 foram excluídos pelos critérios de exclusão. Foram incluídos 48 pacientes, entretanto, 10 pacientes foram excluídos prérandomização. Foram avaliados inicialmente 8 pacientes que foram submetidos a sessões de calor para segurança e validação do método e 30 pacientes foram randomizados até o término do estudo. No total, 38 pacientes foram estudados. Não houve diferença nas características basais entre os grupos estudados. Na primeira fase foram avaliados 38 pacientes, pré e pós-intervenção. A vasodilatação térmica foi capaz de aumentar o índice cardíaco em 24,1% e de reduzir a resistência vascular sistêmica em 16%. Na segunda fase os pacientes foram seguidos por 5 dias consecutivos conforme randomização e apresentaram melhora hemodinâmica significativa somente nos primeiros dois dias. O maior aumento do índice cardíaco foi de 23,3% e a maior redução da resistência vascular sistêmica foi de 19,3% no grupo tratado com calor. A partir do terceiro dia não houve mais benefício da termoterapia. Da mesma forma, não verificamos diferença entre os níveis de BNP dosados entre o primeiro e quinto dias de seguimento entre os grupos. Conclusões: o calor como vasodilatador foi capaz de aumentar o índice cardíaco e diminuir a resistência vascular sistêmica nos primeiros dias de tratamento na ICD. Entretanto, não houve benefício adicional em sessões repetidas por cinco dias consecutivos ou melhora dos níveis de BNP. Os dados sugerem que a termoterapia pode vir a representar uma abordagem terapêutica adjuvante para o tratamento dos pacientes com ICD. No entanto, um ensaio clínico randomizado com número maior de pacientes é necessário para explorar sua potencial efetividade clínica / Background: adjuvant measures have been proposed for the treatment of heart failure patients, some non-pharmacological, such as the use of heat. Despite the positive results for clinically stable patients, there are no studies related to use thermal therapy in patients with decompensated heart failure (DHF) and in use of vasoactive drugs. Objectives: To evaluate the acute hemodynamic effects of heat applied through the thermal blanket in patients with refractory decompensated heart failure. It was established as outcomes the increase of cardiac index and decrease of systemic vascular resistance on the first day of follow-up. Secondary objective was to evaluate whether repeated sessions of heat for five consecutive days would promote or sustain the hemodynamic effects obtained acutely, and if it would reduce BNP levels during the follow-up. Methods: open label randomized clinical trial, with control group, in patients with DHF. The study was divided into two phases. In the first phase, patients were studied in a single day and the acute effects of heat were evaluated before and after intervention. In the second phase, the effects of heat were evaluated by daily sessions for five consecutive days. An infrared thermal blanket was used to heating the patients. Hemodynamic measurements were assessed through invasive Swan-Ganz catheter and noninvasively by the method of modelflow. The patients were receiving continuous intravenous inotropic therapy and were classified in the profile C according to Stevenson´s clinical and hemodynamic classification and were considered refractory after failure in the attempted of withdraw the vasoactive drugs. The study population was divided into 2 groups: group T (thermal therapy) and group C (control). Group T was submitted to vasodilation through the thermal blanket at 50 °C for 40 minutes in addition to drug treatment. Patients in group C maintained the drug treatment and the thermal blanket was positioned in the same way for 40 minutes, but turned off. Statistical analysis: The variables were analyzed by Fisher\'s exact test or likelihood ratio. Normality was assessed with Komogorov-Smirnov test. Quantitative variables were presented as mean and standard deviation. Means were evaluated using analysis of variance for repeated measures (ANOVA). When significant, contrasts were used to discriminate the differences between times. Measurements evaluated at a single time were compared with Student\'s t test. We used the Pearson correlation coefficient to analyze the correlation between the measurements. A p-value < 0.05 was considered statistically significant. Results: Between October 2007 and April 2013, 165 patients were evaluated for possible eligibility. Of these, 12 patients refused to participate in the study and 105 were excluded by the exclusion criteria. There were included 48 patients, however, 10 patients were excluded in the pre-randomization. Eight patients were initially evaluated and were submitted to heart sessions for security and validation of the method and 30 patients were randomized until the end of the study. In total, 38 patients were studied. There were no differences in the baseline characteristics between the study groups. In the first phase, 38 patients were analyzed pre and post-intervention. The thermal vasodilation was able to increase the cardiac index by 24.1% and to reduce the systemic vascular resistance by 16%. In the second phase, patients were followed up for 5 consecutive days according to randomization and showed significant hemodynamic improvement only in the first two days. The largest increase in cardiac index was 23.3 % and the greatest reduction in systemic vascular resistance was 19.3 % in the group treated with heat. From the third day there was no benefit of thermal therapy. Likewise, there was no difference in the levels of BNP measured in the first and fifth day of follow-up between groups. Conclusions: heat as a vasodilator was able to increase the cardiac index and lower the systemic vascular resistance in the first days of treatment in the DHF. However, there was no additional benefit in repeated sessions for five consecutive days or improvement in the BNP levels. The data suggest that thermal therapy may come to represent a therapeutic approach for the adjuvant treatment of patients with DHF. Nonetheless, a randomized clinical trial with a larger number of patients is needed to explore its potential clinical effectiveness