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Lung tumor motion due to respiration poses a challenge in the application of modern three-dimensional conformal radiotherapy. Direct tracking of the lung tumor during radiation therapy is very difficult without implanted fiducial markers. Indirect tracking relies on the correlation of the tumor's motion and the surrogate's motion. The present paper presents(More)
Cone beam CT (CBCT) has been widely used for patient setup in image-guided radiation therapy (IGRT). Radiation dose from CBCT scans has become a clinical concern. The purposes of this study are (1) to commission a graphics processing unit (GPU)-based Monte Carlo (MC) dose calculation package gCTD for Varian On-Board Imaging (OBI) system and test the(More)
PURPOSE To evaluate the initial clinical experience with a frameless and maskless technique for stereotactic radiosurgery using minimal patient immobilization and real-time patient motion monitoring during treatment. We focus on the evaluation of the patient treatment process. METHODS AND MATERIALS The study considered the first 23 patients treated with(More)
BACKGROUND Frameless stereotactic radiosurgery is commonly used to treat intracranial metastases, but mask-based immobilization can be uncomfortable for patients. OBJECTIVE To describe the clinical outcomes using a novel real-time, frameless, surface imaging--guided radiosurgery (SIG-RS) technique to treat brain metastases. METHODS Data were(More)
Algorithms for direct tumor tracking in rotational cone-beam projections and for reconstruction of phase-binned 3D tumor trajectories were developed. The feasibility of the algorithm was demonstrated on a digital phantom, a physical phantom and two patients. Tracking results were obtained by comparing reference templates generated from 4DCT to rotational(More)
We have previously assessed the use of the diaphragm as a surrogate for predicting real-time tumor position with linear models built with training data extracted from the same treatment fraction (Cerviño et al 2009 Phys. Med. Biol. 54 3529-41). However, practical use in the clinical setting requires the capability of predicting tumor position throughout the(More)
The patient respiratory signal associated with the cone beam CT (CBCT) projections is important for lung cancer radiotherapy. In contrast to monitoring an external surrogate of respiration, such a signal can be extracted directly from the CBCT projections. In this paper, we propose a novel local principal component analysis (LPCA) method to extract the(More)
Precise tracking of lung tumor motion during treatment delivery still represents a challenge in radiation therapy. Prototypes of MRI-linac hybrid systems are being created which have the potential of ionization-free real-time imaging of the tumor. This study evaluates the performance of lung tumor tracking algorithms in cine-MRI sagittal images from five(More)
Respiratory motion during free-breathing computed tomography (CT) scan may cause significant errors in target definition for tumors in the thorax and upper abdomen. A four-dimensional (4D) CT technique has been widely used for treatment simulation of thoracic and abdominal cancer radiotherapy. The current 4D CT techniques require retrospective sorting of(More)
Late cardiac complications may arise after left-breast radiation therapy. Deep-inspiration breath hold (DIBH) allows reduction of the irradiated heart volume at the same time as it reduces tumor bed motion and increases lung sparing. In the present study, we have evaluated the improvement in reproducibility and stability of the DIBH for left-breast-cancer(More)