This study explores the potential of cone-beam computed tomography (CBCT) for monitoring relative beam range variations due to daily changes in patient anatomy for prostate treatment by anterior proton beams. CBCT was used to image an anthropomorphic pelvic phantom, in eight sessions on eight different days. In each session, the phantom was scanned twice, first at a standard position as determi...

Leksell Gamma Knife® IconTM with integrated Cone Beam CT (CBCT) system provides increased workflow flexibility with e.g. planning on frameless images and subsequent frameless dose delivery. The stereotactic reference is given by the CBCT images taken prior to treatment. Co-registration of the planning image volume with the CBCT volume gives the transformation mapping of the planned isocenter po...

The purpose of this study was to investigate the impact of different CBCT imaging monitor units (MUs), reconstruction slice thicknesses, and planning CT slice thicknesses on the positioning accuracy of a megavoltage cone-beam computed tomography (MV-CBCT) system in image-guided radiation therapy (IGRT) in head-and-neck patients. The MV-CBCT system was a Siemens MVision, a commercial system inte...

BACKGROUND Modern radiotherapy offers various possibilities for image guided verification of patient positioning. Different clinically relevant IGRT (image guided radiotherapy) scenarios were considered with regard to their influence on dosimetric plan quality and normal tissue complication probability (NTCP). METHODS This study is based on treatment plans of 50 prostate patients. We evaluate...

The purpose of this study was to assess quantitatively elongation of mobile targets in cone-beam CT (CBCT) imaging by measurement and modeling. A mathematical model was derived that predicts the measured lengths of mobile targets and its dependence on target size and motion patterns in CBCT imaging. Three tissue-equivalent targets of differing sizes were inserted in an artificial thorax phantom...

OBJECTIVES/HYPOTHESIS Cone beam computed tomography (CBCT) has emerged as a low radiation dose alternative to traditional computed tomography (CT) to evaluate the paranasal sinuses. The purpose of our study was to determine how often clinically important findings would be missed if CBCT was used routinely for sinus imaging. STUDY DESIGN Retrospective review. METHODS We evaluated all maxillo...

Registration of endoscopic video to preoperative CT facilitates high-precision surgery of the head, neck, and skull-base. Conventional video-CT registration is limited by the accuracy of the tracker and does not use the underlying video or CT image data. A new image-based video registration method has been developed to overcome the limitations of conventional tracker-based registration. This me...

OBJECTIVES The aim of this study was to investigate the accuracy and reliability of linear measurements of edentulous ridges recorded from 16-row multidetector CT (MDCT) images and cone beam CT (CBCT) images acquired using a flat panel detector (FPD) with a large field of view (FOV), both independently and in comparison with each other. METHODS Edentulous areas of human dry skulls were marked...

BACKGROUND The cone-beam computerized tomography (CBCT) has become widely used for oral and maxillofacial imaging, providing a good spatial resolution, gray density range, and contrast, as well as a good pixel/noise ratio. In the CBCT the dimensional accuracy is also comparable with Computer Tomography (CT), but in contrast to the CT, the gray density values of the CBCT images (voxel value [VV]...

BACKGROUND To evaluate the accuracy of using kilovoltage x-ray cone-beam computed tomography (kV-CBCT) imaging for in vivo dose calculations. METHODS A Region-of-Interest (ROI) CT number mapping method was developed to generate the cone-beam CT number vs. relative electron density calibration curve for 3D dose calculations. The stability of the results was validated for three consecutive mont...