Prostate cancer is prevalent among men and one of the few cancer sites where local therapies currently target the entire organ instead of tumour. MRI holds promise in accurately depicting regions of cancer burden within the prostate gland and guiding tumour-targeted diagnostics and therapeutics. The clinical performance of a novel stereotactic MRI-guided needle navigation system for prostate cancer targeting was evaluated. Mean absolute in-plane stereotactic needle-targeting error for 10 patients was 2.2 mm and mean absolute depth error was 6.5 mm, highlighting a need to improve technical accuracy of the system. Consequently, alternative stereotactic registration techniques were investigated. Metrics of performance were in-plane stereotactic needle-targeting error, depth error, and registration time. A Z-shaped fiducial motif using automated registration performed best in phantom experiments with an in-plane error of 2.0 mm and depth error of 1.0 mm. These results will guide further software and hardware development to improve clinical performance.

No / This case study describes a qualitative investigation of the experiences of 14 experienced mammography radiographers who successfully undertook a formal programme of education and training in stereotactic needle core biopsy (SNCB) of the breast. They now routinely perform SNCB within symptomatic and screening breast services in a variety of NHS hospitals across the country. All 14 radiographers completed a semi-structured postal questionnaire approximately six months after the end of the course. A tentative theory derived from the data suggests that the professional challenge associated with radiographer-performed SNCB builds personal confidence and effects positive change. Three main categories emerging from the data e challenge, confidence and change are underpinned by two main themes e educational, professional and service drivers that promote the realisation of goals and vision; and personal, peer and external motivation sustained by respect, recognition and reward. SNCB role extension as explored in this study is having a positive and transformational impact on patient users of breast diagnostic clinical services and on the professional health carers providing them. The key drivers for this as identified in the study are a formal educational experience, professional role extension opportunities and the NHS modernisation process. The participants experienced positive change as individuals and as professional breast cancer multidisciplinary team members. Academic and financial rewards, respect and recognition from colleagues across professional disciplines and from patients, were key motivators that sustained the process. This study indicates that radiographer-performed SNCB can help deliver the NHS Plan and the NHS Cancer Plan and in doing so has the potential to improve the working lives of health care professionals and ultimately to improve the quality of care for patients.

Radio frequency (RF) lesioning and deep brain stimulation (DBS) are the two prevailing surgical treatments for movement disorders within the field of stereotactic and functional neurosurgery. For RF-lesioning, a small volume of brain tissue is coagulated and knowledge of the lesion size and growth is of great importance for the safety and outcome of the procedure. This thesis deals with adapting the laser Doppler perfusion monitoring (LDPM) technique for measurements in brain tissue during RF-lesioning. The relation between LDPM signal changes and developed lesion size was investigated. LDPM measurements were evaluated both in vitro (albumin protein solution) and in vivo in the porcine brain during RF-lesioning corresponding to a bilateral thalamotomy in man. The investigated signals from the LDPI measurements can be used for following the lesioning time course and to detect if a lesion was created, both in vitro and in the animal model. For the albumin model, both the total backscattered light intensity and the perfusion signal can be used as markers for estimating the final coagulation size, while in the animal model this conclusion was not statistical verified. Independent on surgical method, RF-lesioning or DBS, intracerebral guidance is an important aspect within stereotactic and functional neurosurgery. To increase the accuracy and precision of reaching the correct target, different methods for intracerebral guidance exist, such as microelectrode recording and impedance methods. In this thesis, the possibility of developing an optical intracerebral guidance method has been investigated. Diffuse reflectance spectroscopy served as technology and all measurements were performed stereotactically in both porcine and human brain. Measurements of white and gray matter showed large differences, with higher reflectivity for white brain matter, both in porcine and in human brain. For the human measurements during DBS-implants, large differences between white matter and functional targets were found. Additionally, differences between native and lesioned porcine brain matter were detected. Both studies support the idea of using diffuse reflectance spectroscopy for developing an intracerebral guidance method.

No description available.

Image guided therapy procedures under MRI guidance has been a focused research area over past decade. Also, over the last decade, various MRI guided robotic devices have been developed and used clinically for percutaneous interventions, such as prostate biopsy, brachytherapy, and tissue ablation. Though MRI provides better soft tissue contrast compared to Computed Tomography and Ultrasound, it poses various challenges like constrained space, less ergonomic patient access and limited material choices due to its high magnetic field. Even after, advancements in MRI compatible actuation methods and robotic devices using them, most MRI guided interventions are still open-loop in nature and relies on preoperative or intraoperative images. In this thesis, an intraoperative MRI guided robotic system for prostate biopsy comprising of an MRI compatible 4-DOF robotic manipulator, robot controller and control application with Clinical User Interface (CUI) and surgical planning applications (3DSlicer and RadVision) is presented. This system utilizes intraoperative images acquired after each full or partial needle insertion for needle tip localization. Presented system was approved by Institutional Review Board at Brigham and Women's Hospital(BWH) and has been used in 30 patient trials. Successful translation of such a system utilizing intraoperative MR images motivated towards the development of a system architecture for close-loop, real-time MRI guided percutaneous interventions. Robot assisted, close-loop intervention could help in accurate positioning and localization of the therapy delivery instrument, improve physician and patient comfort and allow real-time therapy monitoring. Also, utilizing real-time MR images could allow correction of surgical instrument trajectory and controlled therapy delivery. Two of the applications validating the presented architecture; closed-loop needle steering and MRI guided brain tumor ablation are demonstrated under real-time MRI guidance.

"This thesis presents a single-slice based fast stereotactic registration and tracking technique along with a corresponding modular system for guiding robotic mechanism or interventional instrument to perform needle-based interventions under live MRI guidance. The system can provide tracking of full 6 degree-of-freedom (DOF) in stereotactic interventional surgery based upon a single, rapidly acquired cross-sectional image. The whole system is constructed with a modular data transmission software framework and mechanical structure so that it supports remote supervision and manipulation between a 3D Matlab tracking user interface (UI) and an existing MRI robot controller by using the OpenIGTLink network communication protocol. It provides better closed-loop control by implementing a feedback output interface to the MRI-guided robot. A new compact fiducial frame design is presented, and the fiducial is wrapped with a passive resonant coil. The coil resonates at the Larmor frequency for 3T MRI to enhance signal strength and enable for rapid imaging. The fiducial can be attached near the distal end of the robot and coaxially with a needle so as to visualize target tissue and track the surgical tool synchronously. The MRI-compatible design of fiducial frame, robust tracking algorithm and modular interface allow this tracking system to be conveniently used on different robots or devices and in different size of MRI bores. Several iterations of the tracking fiducial and passive resonant coils were constructed and evaluated in a Phillips Achieva 3T MRI. To assess accuracy and robustness of the tracking algorithm, 25 groups of images with different poses were successively scanned along specific sequence in and MRI experiment. The translational RMS error along depth is 0.271mm with standard deviation of 0.277mm for totally 100 samples. The overall angular RMS error is less than 0.426 degree with standard deviation of 0.526 degree for totally 150 samples. The passive resonant coils were shown to significantly increase signal intensity in the fiducial relative to the surroundings and provide for rapid imaging with low flip angles. "

Die fraktionierte stereotaktisch geführte Radiotherapie stellt eine Möglichkeit der Behandlung intrakranieller Tumoren dar, bei denen eine chirurgische Resektion nicht oder nicht vollständig möglich ist. Ziel dieser Arbeit war der Vergleich der Dosisverteilung von Bestrahlungsplänen, die mittels fluenzmodulierter (IMRT) und 3D konformaler stereotaktisch geführter Bestrahlungstechnik (conformal beam) für Hypophysenadenome und petroclivale Meningeome erstellt wurden. Auf Basis des CT-Datensatzes eines Alderson-Phantoms erfolgten zunächst die systematische Untersuchung der IMRT Eingabeparameter und die Definition von Dosis-Volumen-Constraints für beide Tumorentitäten. Im Anschluss wurden die gewonnenen Erkenntnisse bei der fluenzmodulierten Bestrahlungsplanung von 10 realen Patienten, 5 je Tumorentität, angewendet. Zusätzlich wurde für jeden dieser Patienten ein 3D konformaler Bestrahlungsplan erstellt. Die Evaluation der Bestrahlungspläne erfolgte durch verschiedene quantitativer Parameter unter Einbeziehung der subjektiven Beurteilung der Dosisverteilung. Bei beiden Tumorentitäten lieferte in je 4 von 5 Fällen die IMRT einen Vorteil gegenüber der conformal beam Bestrahlung, der vor allem auf der besseren Erfassung, Dosishomogenität und höheren Median-Dosis im bestrahlten Zielvolumen (PTV) beruhte. Komplex geformte Zielvolumina profitierten dabei besonders von der Fluenzmodulation. Dem stand jedoch in einigen Fälle eine stärke Belastung der Risikoorgane (OAR) mit einer höheren Dosis und die generell höhere Anzahl notwendiger Monitoreinheiten gegenüber. Zuletzt wurde auf Basis von MatLAB eine Software entwickelt, welche die Verifikation von stereotaktisch geführten IMRT-Bestrahlungen und die Analyse von Winston-Lutz-Tests ermöglicht.

Η ακτινοθεραπεία αποτελεί μια απο τις βασικές θεραπείες κατά του καρκίνου. Για τη σωστή θεραπεία η ακριβής δόση ακτινοβολίας θα πρέπει να έχει υπολογιστεί. Ο υπολογισμός αυτός της δόσης ακτινοβολίας δυσκολεύει λόγω της διαφορετικής πυκνότητας ιστών του ανθρώπινου σώματος (πνεύμονες, αέρινες κοιλότητες, κόκαλα, κτλ). Η μελέτη της επίδρασης αυτών των ετερογενειών αλλά και μέθοδοι διόρθωσης της δόσης είναι μέρος αυτής της διδακτορικής διατριβής. Επίσης η θεραπεία όγκων στην περιοχή της κεφαλής με στεροτακτική ακτινοθεραπεία εξετάζεται στη διατριβή αυτη. Οι υπολογισμοί της δόσης στην στεροτακτική ακτινοθεραπεία απαιτούν μεγάλη ακρίβεια και στη διατριβή αυτή μελετάται η μέθοδος Μόντε Κάρλο για το υπολογισμό της δόσης / Radiotherapy is one of the principal modalities for used in treatment of malignant disease. For a correct therapy, the calculation of the delivered dose should be performed with great accuracy. This calcilation becomes difficult when heterogeneities of the human body are involved (lungs, air cavities, bones, etc). In this thesis, we studied the effect of such heterogeneities. We have also proposed methods of accuratley calculating the dose when heterogeneities are present inthe radiation field. Another aspect of radiotherapy is stereotactic radiotherapy for head and neck tumors. The demand of accurate dose calculation is even greater in this cases. W have studied methods of calculting the doses for stereotactic radiotherapy fields. The Monte Carlo methos proved to be the mostaccurate in this case.

INTRODUCTION: Cancers of the gastrointestinal tract are the second most prevalent malignancy with 289,610 new cases last year and the second most common cause of cancer-related death with 150,000 deaths last year in the United States. Prognosis for patients with these malignancies is poor and worsens significantly once the cancer has metastasized to the brain. We evaluated the outcome of patients following Stereotactic Radiosurgery (SRS) for brain metastases (BM) in individuals with GI cancers to identify safety and effectivity of treatment and we assessed prognostic factors that affect tumor control and survival. OBJECTIVES: By the conclusion of this session, participants should be able to: 1) Identify an effective treatment for brain metastases from GI cancers in terms of increasing survival; 2) Identify which treatment provides the best local and distant control of CNS disease; 3) Discuss the effects of different prognostic factors on local control and survival. METHODS: This is a retrospective analysis of 58 brain metastases from 18 consecutive patients who underwent SRS treatment at BIDMC between 2006 and 2013. 11/18 patients underwent prior microsurgical resection for their metastases and 3/18 patients had undergone Whole Brain Radiation Therapy (WBRT). Overall Survival (OS), Local Control (LC), Distal control (DC), and prognostic factors such as age, number of brain metastases (BM), Karnofsky Performance Status (KPS), Recursive Partition Analysis (RPA) and Disease Specific Graded Prognostic Assessment (Ds-GPA) class were evaluated. RESULTS: The median overall survival (mOS) for the entire cohort was 14 months after the diagnosis of BM. The mOS for patients receiving only SRS, Surgical Resection + SRS, and WBXRT + SRS were 8 months, 18 months, and 13 months respectively. The difference in overall survival between treatment groups was not found to be statistically significant. Increasing number of BM was a factor shown to negatively influence survival. Local control was achieved in 55% of lesions after SRS, and in 75% of lesions that were surgically resected followed by SRS boost to the resection cavity. The difference in local control between SRS alone vs. Surgery + SRS was found to be statistically significant (p = 0.013). CONCLUSION: With a higher overall survival and significantly better local control rates, Surgery followed by SRS boost to the resection cavity should be considered as the treatment of choice in this specific subgroup of cancer patients as this study shows that they benefit from this more aggressive treatment option.

The use of stereotactic body radiation therapy employing few large fractions of radiation dose for the treatment of non-small cell lung cancer has been proven very successful, high values of tumour control probability (TCP) being clinically achieved. In spite of the success of the fractionation schedules currently used, there is a tendency towards reducing the number of fractions for economical and practical reasons, and also for maximizing the comfort of the patients. It is therefore the main aim of this thesis to investigate the impact of a severely reduced number of fractions on the tumour control probability for tumours that contain hypoxic areas. The impact on TCP of other factors such as hypoxic fraction, distribution of the oxygen partial pressure and location of the hypoxic volume within the tumour were also investigated. The effect of tumour motion due to breathing was included and evaluated using Cone Beam Computed Tomography (CBCT) data from patients imaged with internal markers in the liver and pancreas. The results clearly showed that in the presence of hypoxia, TCP is seriously compromised if there is not enough time for reoxygenation between fractions. A reduction in the number of fractions of just one fraction may require an increase of several Gy per fraction to obtain a similar TCP. The diaphragmatic tumour motion range showed little influence on TCP provided that the PTV encompassed all tumour positions. The dose delivered to the PTV margin was found not to be the only factor that is significant for local control, the average dose correlated better with TCP. The agreement of the results of this work with clinical results also serve as a strong indicator that inter-fraction reoxygenation is an important process in real-life patients treated with stereotactic body radiotherapy.