Darbo tikslas. Atsitiktinės atrankos perspektyviniame klinkiniame tyrime nustatyti ir palyginti lokalaus priešinės liaukos vėžio įprastai frakcionuoto (CFRT) ir hipofrakcionuoto (HFRT) išorinio trimačio konforminio spindulinio gydymo sukeliamas ūmines spindulines reakcijas, gydymo efektyvumą, bei lėtines spindulines reakcijas. Tyrimo medžiaga ir metodai. CFRT taikyta 44 pacientams, švitinta prostata ir sėklinių pūslelių pagrindas 37 frakcijos po 2,0 Gy iki suminės 74 Gy dozės. HFRT taikyta 47 pacientams, toks pat taikinys švitintas 13 frakcijų po 3,0 Gy ir 4 frakcijos po 4,5 Gy iki suminės 57 Gy dozės. Pacientai stebėti mažiausiai 2 metus. Rezultatai. Ūminių 2 laipsnio šlapimo pūslės spindulinių reakcijų buvo statistiškai reikšmingai mažiau HFRT pacientų grupėje. Visų tiesiosios žarnos ūminių spindulinių reakcijų trukmė buvo mažesnė HFRT grupėje . Lėtinių šlapimo pūslės ir tiesiosios žarnos spindulinių reakcijų dažnumas pacientų grupėse nesiskyrė. Biocheminio atsako į gydymą dydis ir greitis pacientų grupėse per 2 metų stebėjimo laiką nesiskyrė. Išvados. Taikytas hipofrakcionuotas išorinis lokalaus prostatos vėžio spindulinis gydymas yra saugus, tačiau atokiam šio gydymo metodo efektyvumui nustatyti reikalingas ilgesnis pacientų stebėjimo laikas. / The aim of the study. To investigate and compare toxicity and efficacy of conventionally fractionated (CFRT) vs. hypofractionated (HFRT) three dimensional conformal external beam radiotherapy for localized prostate carcinoma within prospective randomized study. Matherial and Methods. Forty-four patients in the CFRT treatment arm were irradiated with 74 Gy in 37 fractions (2 Gy per fraction), and 47 in the HFRT arm were treated with 57 Gy, given in 13 fractions of 3 Gy plus 4 fractions of 4.5 Gy. The clinical target volume includes the prostate and a base of seminal vesicles. A minimum follow-up was 2 years. Results. The only grade 2 genitourinary acute toxicity proportion was significantly lower in the HFRT arm. The median duration of overall gastrointestinal acute toxicity was significantly shorter with HFRT. There were no statistically significant differences in the late toxicity rates, biochemical tumor response rates and time to the response between study arms during 2 year follow-up. Conclusions. The investigated hypofractionated 3DCRT for localized prostate carcinoma found to be safe, but extended follow-up is needed to justify the efficacy of our fractionation schedule in the long term.

Introduction: Despite the public and policy attention on ensuring access to health care for all Canadians, research continues to identify inequities in access to cancer care services. The objectives of this thesis are to define inequity in access to colorectal cancer (CRC), as well as to measure inequity in access to radiotherapy and end-of-life care. Methods: This study examined income-, geography-, sex-, and age-related inequity in access to CRC services along the continuum of care, using the Horizontal Inequity Index. Specifically, we measured and compared inequity in access CRC services in Nova Scotia using linked administrative databases. Results: We have identified that age- and geography-related inequity in access to radiotherapy and end-of-life care are the most consistent for CRC patients in Nova Scotia. Discussion: The clear distinction between inequity and inequality in this study provides indication to policy makers that the variations in access, may be of social concern.

Brachytherapy is an important method of breast cancer treatment; however, improvements in both treatment planning and delivery are needed. The procedure involves insertion of catheters in the tumor site, which, in current practice, is prone to clinically significant error. In order to improve on contemporary catheter placement accuracy, integration of pre-operative imaging, supplemented by computerized surgical planning and mathematical optimization were used to develop and test an intra-operative immobilization and catheter guidance system. A custom-template specific to each patient with optimally-placed guide-holes for catheter insertion was designed and fabricated for use on phantom studies. Template creation is based on a virtual reality reconstruction of the patient's anatomy from computed tomography imaging. The template fits on the patient's breast, immobilizing the soft tissue, to provide pre-planned catheter insertion holes for guidance to the tumor site. Agar-based phantom and target models were used for quantitative validation of the template using computed tomography imaging for template planning and validation. Planned catheter tracks were compared to post-insertion image data and distance measurements from target location were used to create an error measure. Using the latest template design spanning multiple experiments resulted in a mean of 2.6 mm, 95%, CI =3.1-2.2, which is within the clinically acceptable range of 3 mm, as validated with our clinical collaborators. Validation of the brachytherapy template on phantom tissue produced clinically acceptable results. Use of a patient-specific template for breast brachytherapy is feasible and may improve the procedure accuracy and outcome. This work has been a proof-of-concept, providing evidence to support moving forward with the next phase of patient-specific breast template trials for use in brachytherapy. / Thesis (Master, Computing) -- Queen's University, 2011-10-03 15:17:07.933

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In this work we introduce PARETO, a multiobjective optimization tool that simultaneously optimizes beam angles and fluence patterns in intensity-modulated radiation therapy (IMRT) treatment planning using a powerful genetic algorithm. We also investigate various objective functions and compare several parameterizations for modeling beam fluence in terms of fluence map complexity, solution quality, and run efficiency. We have found that the combination of a conformity-based Planning Target Volume (PTV) objective function and a dose-volume histogram or equivalent uniform dose -based objective function for Organs-At-Risk (OARs) produced relatively uniform and conformal PTV doses, with well-spaced beams. For two patient data sets, the linear gradient and beam group fluence parameterizations produced superior solution quality using a moderate and high degree of modulation, respectively, and had comparable run times. PARETO promises to improve the accuracy and efficiency of treatment planning by fully automating the optimization and producing a database of non-dominated solutions for each patient.

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Anatomical changes can have significant clinical impact during head and neck radiotherapy. Adaptive radiotherapy (ART) may be applied to account for such changes. Implementation of ART to alter dose delivery requires deformable image registration (DIR) to assess 3D deformations. This study evaluates the performance and accuracy of a commercial DIR system for clinical applications. The investigations in this project were carried out using images of induced changes in two standard radiotherapy phantoms (RANDO® and CIRS®) and one in-house built phantom. CT image data before and after deformation of the phantoms were processed using Eclipse / SmartAdapt® v.10 system employing a Demons-based algorithm. A DIR protocol was designed, and algorithm performance was assessed quantitatively, using volume analysis and the Dice Similarity Index (DSI), and also evaluated qualitatively. In addition, algorithm performance was assessed for 5 head and neck cancer patients using clinical CT images. Each original planning CT image containing contours of 10 volumes of interest including treatment target volumes and organs at risk was deformed to match a second CT image acquired during the course of the treatment. The original structures were deformed, copied onto the target image and compared to reference contours drawn by 3 radiation oncologists. Phantom investigations gave varied results with average DSI scores ranging from 0.69 to 0.93, with an overall average of 0.86 ± 0.08. These quantitative results were reflected qualitatively, with generally accurate matching between reference and DIR-generated structures. Although air gaps in the phantoms compromised algorithm performance and gave rise to physically aberrant results. Clinical results were generally better with a DSI range of 0.75-0.99 and an overall average of 0.89 ± 0.05, suggesting high DIR accuracy. Qualitatively, some minor contour deformations were noted, as well as artefacts in the axial direction that were due to the CT slice resolution (3 mm) that was used to scan the patients. In addition, contour propagation between images using DIR reduced the time required by physicians to contour the images of head and neck cancer patients by ~47%. This study demonstrated that deformable image registration using a Modified Demons algorithm yields clinically acceptable results and time-saving benefits in contouring that improve clinical workflow. The study also showed that it is feasible to incorporate deformable image registration as part of an adaptive radiotherapy strategy for head and neck cancer, provided further studies are designed to carry out accurate and verifiable dose deformation.

The expectation for continual improvements in the treatment of cancer has brought quality assurance in radiotherapy under scrutiny in recent years. After a cancer diagnosis a custom treatment plan is devised to meet the particular needs of the patient's condition based on their prognosis. A cancer treatment plan will typically comprise of several cancer treatment technologies combining to form a comprehensive programme to fight the malignant growth. Inherent in each cancer treatment technology is a percentage error in treatment accuracy. Quality assurance is the medical practice to minimise the percentage error in treatment accuracy. Radiotherapy is one of the several cancer treatment technologies a patient might receive as part of their treatment plan, and in-vivo dosimetry is a quality assurance technology specifically designed to minimise the percentage error in the treatment accuracy of radiotherapy. This thesis outlines the work completed in the design of a next generation dosimeter for in-vivo dosimetry. The proposed dosimeter is intended to modernise the process of measuring the absorbed dose of ionising radiation received by the target volume during a radiotherapy session. To accomplish this goal the new dosimeter will amalgamate specialist technologies from the field of particle physics and reapply them to the field of medical physics. This thesis describes the design of a new implantable in-vivo dosimeter, a dosimeter comprising of several individual stages of electronics working together to modernise quality assurance in radiotherapy. Presented within this thesis are the results demonstrating the performance of two critical stages for this new dosimeter, including: the oating gate metal oxide field effective transistor, a radiation sensitive electronic component measuring an absorbed dose of radiation; and the micro antenna, a highly specialist wireless communications device working to transmit a high frequency radio signal. This was a collaborative project between Rutherford Appleton Laboratory and Brunel University. The presented work in this thesis was completed between March 2007 and January 2011.