Image Guidance

Angesichts der zunehmenden strukturellen Verschaltung von Mensch und Maschine in der chirurgischen Praxis selbst genügt es nicht mehr, pathologische Veränderungen auf der Basis eines entsprechend theoriegeleiteten Bildwissensauf in medizinischen Visualisierung „lediglich“ zu erkennen. Bildkompetent müss ChirurgInnen inzwischen nicht mehr nur als DiagnostikerInnen sein, sondern Bilder gestalten zunehmend auch die Therapie. Visualisierungspraktiken lenken, steuern, führen und gestalten inwischen auch den Behandlungsprozess und etablieren ein verändertes Verhältnis zwischen ChirurgIn und PatientIn, zwischen Körper und Bild, zwischen Mensch und Maschine. Der Beitrag untersucht dieses Gefüge von Anschauung, Operativität und Bildlichkeit in der minimal-invasiven Chrirurgie anhand der medialen Produktionsbedingungen des roboter-assistierten Operationssystems Da Vinci. Dabei wird anhand konkreter Fallbeispiele der Architektur, Navigation und Steuerung des Systems gezeigt, dass dem Herstellerversprechen erhöhter medizinischer Effizienz und Präzision bildgeführter Operationssysteme eine praktische Kenntnis der Differenz zwischen Körper und Bild entgegenstehen muss, die nicht in Abrenzung zum Maschinellen verhandelt werden kann, sondern als Synthese von Chirurg und Operationssystem gedacht werden muss.

Percutaneous cholecystostomy (PC), a technique that consists of percutaneous catheter placement in the gallbladder lumen under imaging guidance, has become an alternative to surgical cholecystostomy in recent years. Indications of PC include calculous or acalculous cholecystitis, cholangitis, biliary obstruction and opacification of biliary ducts. It also provides a potential route for stone dissolution therapy and stone extraction. Under aseptic conditions

Radiation therapy has gone through a series of revolutions in the last few decades and it is now possible to produce highly conformal radiation dose distribution by using techniques such as intensity-modulated radiation therapy (IMRT). The improved dose conformity and steep dose gradients have necessitated enhanced patient localization and beam targeting techniques for radiotherapy treatments. Components affecting the reproducibility of target position during and between subsequent fractions of radiation therapy include the displacement of internal organs between fractions and internal organ motion within a fraction. Image-guided radiation therapy (IGRT) uses advanced imaging technology to better define the tumor target and is the key to reducing and ultimately eliminating the uncertainties. The purpose of this article is to summarize recent advancements in IGRT and discussed various practical issues related to the implementation of the new imaging techniques available to radiation ...

Advances in conformal radiation therapy and advancements in pre-clinical radiotherapy research have recently stimulated the development of precise micro-irradiators for small animals such as mice and rats. These devices are often kilovolt x-ray radiation sources combined with high-resolution CT imaging equipment for image guidance, as the latter allows precise and accurate beam positioning. This is similar to modern human radiotherapy practice. These devices are considered a major step forward compared to the current standard of animal experimentation in cancer radiobiology research. The availability of this novel equipment enables a wide variety of pre-clinical experiments on the synergy of radiation with other therapies, complex radiation schemes, sub-target boost studies, hypofractionated radiotherapy, contrast-enhanced radiotherapy and studies of relative biological effectiveness, to name just a few examples. In this review we discuss the required irradiation and imaging capabilities of small animal radiation research platforms. We describe the need for improved small animal radiotherapy research and highlight pioneering efforts, some of which led recently to commercially available prototypes. From this, it will be clear that much further development is still needed, on both the irradiation side and imaging side. We discuss at length the need for improved treatment planning tools for small animal platforms, and the current lack of a standard therein. Finally, we mention some recent experimental work using the early animal radiation research platforms, and the potential they offer for advancing radiobiology research.

Brachytherapy has consistently provided a very conformal radiation therapy modality. Over the last two decades this has been associated with significant improvements in imaging for brachytherapy applications (prostate, gynecology), resulting in many positive advances in treatment planning, application techniques and clinical outcome. This is emphasized by the increased use of brachytherapy in Europe with gynecology as continuous basis and prostate and breast as more recently growing fields. Image guidance enables exact knowledge of the applicator together with improved visualization of tumor and target volumes as well as of organs at risk providing the basis for very individualized 3D and 4D treatment planning. In this commentary the most important recent developments in prostate, gynecological and breast brachytherapy are reviewed, with a focus on European recent and current research aiming at the definition of areas for important future research. Moreover the positive impact of GE...

Traditional oncology distinguishes between two separate and incommensurable states in the evolution of solid malignancies: the localized disease, which is curable; and the disseminated status, which is per se palliative. Recently, a huge body of evidence suggests a fundamental change in the understanding of cancer, indicating an intermediate state in the trajectory of solid malignancies: the oligometastatic state. The following review will critically analyse existing hypotheses and facts from the basic sciences and try to contextualize it in regard to the clinical evidence available to date. Consecutively, it will try to draw possible clinical consequences for application of radiotherapy in this specific clinical scenario.

To compare the residual setup errors measured with ExacTrac X-ray 6 degree-of-freedom (6D) and cone-beam computed tomography (CBCT) for a head phantom and patients receiving intracranial non-invasive fractionated stereotactic radiotherapy (SRT).Setup data were collected on a Novalis Tx treatment unit for an anthropomorphic head phantom and 18 patients with intracranial tumors. Initial corrections were determined and corrected with the ExacTrac system only, and then the residual setup error was determined by means of three different procedures. These procedures included registrations of ExacTrac X-ray images with the corresponding digitally reconstructed radiographs (DRRs) using the ExacTrac 6D fusion, and registrations of CBCT images with the planning CT using both online 3D fusion and offline 6D fusion. The difference in residual setup errors between ExacTrac system and CBCT was computed. The impact of rotations on the difference was evaluated.A modest difference in residual setup errors was found between ExacTrac system and CBCT. The root-mean-square (RMS) of the differences observed for translations was typically <0.5 mm for phantom, and <1.5 mm for patients, respectively. The RMS of the differences for rotation(s) was however <0.2 degree for phantom, and <1.0 degree for patients, respectively. The impact of rotation on the setup difference was minor but not negligible.This study indicates that there is a general agreement between ExacTrac system and CBCT.

Based on case studies in minimally invasive surgery, the paper investigates how head-mounted displays (HMDs) transform action and perception in the operating theater. In particular, it discusses the methods and addresses the obstacles that are linked to the attempt to eliminate the divide between vision and visualization by augmenting the surgeon’s field of view with images. Firstly, it analyzes how HMDs change the way images are integrated into the surgical workflow by looking at the modalities of image production, transmission, and reception of HMDs. Secondly, it examines how HMDs change where and in which situations images are used by looking at screen architectures in minimally invasive surgery. Thirdly, it discusses the impact of HMD-based practice on action, perception, and decision-making, by examining how HMDs challenge the existing techniques and routines of surgical practice and, therefore, call for a new type of image and application-based expertise.

Summary Cerebrospinal fluid rhinorrhea occurs as a result of abnormal communication between the subarachnoid space and the pneumatized portion of the skull base, the paranasal sinuses and the middle ear. Conservative measures may be sufficient in the management of cerebrospinal fluid rhin- orrhea, but, in some cases, surgical treatment may be required. Transnasal endoscopic techniques are constantly being used in

Background Image-guidance systems allow accurate interfractional repositioning of IMRT treatments, however, these may require up to 15 minutes. Therefore intrafraction motion might have an impact on treatment precision. 3D geometric data regarding intrafraction prostate motion are rare; we therefore assessed its magnitude with pre- and post-treatment fiducial-based imaging with cone-beam-CT (CBCT). Methods 39 IMRT fractions in 5 prostate cancer patients after125I-seed implantation were evaluated. Patient position was corrected based on the125I-seeds after pre-treatment CBCT. Immediately after treatment delivery, a second CBCT was performed. Differences in bone- and fiducial position were measured by seed-based grey-value matching. Results Fraction time was 13.6 ± 1.6 minutes. Median overall displacement vector length of125I-seeds was 3 mm (M = 3 mm, Σ = 0.9 mm, σ = 1.7 mm; M: group systematic error, Σ: SD of systematic error, σ: SD of random error). Median displacement vector of bony structures was 1.84 mm (M = 2.9 mm, Σ = 1 mm, σ = 3.2 mm). Median displacement vector length of the prostate relative to bony structures was 1.9 mm (M = 3 mm, Σ = 1.3 mm, σ = 2.6 mm). Conclusion Overall displacement vector length during an IMRT session is Positioning devices reducing intrafraction bony displacements can further reduce overall intrafraction motion. Intrafraction prostate motion relative to bony structures is IMRT duration.

Ultrasound (US) image guidance systems used in radiotherapy are typically calibrated for soft tissue applications, thus introducing errors in depth-from-transducer representation when used in media with a different speed of sound propagation (e.g. fat). This error is commonly referred to as the speed artifact. In this study we utilized a standard US phantom to demonstrate the existence of the speed