International journal of radiation oncology, biology, physics
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Int. J. Radiat. Oncol. Biol. Phys. · Jul 2009
Semiquantitative and quantitative dynamic contrast-enhanced magnetic resonance imaging measurements predict radiation response in cervix cancer.
To evaluate semiquantitative and quantitative dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) measurements in predicting the response to radiotherapy in cervix cancer. ⋯ This is the first study to show that pretreatment DCE-MRI quantitative parameters predict the radiation response in cervix cancer. These measurements may allow a more meaningful comparison of DCE-MRI studies from different centers.
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Int. J. Radiat. Oncol. Biol. Phys. · Jul 2009
Integration of real-time internal electromagnetic position monitoring coupled with dynamic multileaf collimator tracking: an intensity-modulated radiation therapy feasibility study.
Continuous tumor position measurement coupled with a tumor tracking system would result in a highly accurate radiation therapy system. Previous internal position monitoring systems have been limited by fluoroscopic radiation dose and low delivery efficiency. We aimed to incorporate a continuous, electromagnetic, three-dimensional position tracking system (Calypso 4D Localization System) with a dynamic multileaf collimator (DMLC)-based dose delivery system. ⋯ Real-time target position information was successfully integrated into a DMLC effector system to modify dose delivery. Experimental results show both comparable dosimetric accuracy as well as improved efficiency compared with spatial gating.
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Int. J. Radiat. Oncol. Biol. Phys. · Jul 2009
Evaluation of image-guided positioning for frameless intracranial radiosurgery.
The standard for target alignment and immobilization in intracranial radiosurgery is frame-based alignment and rigid immobilization using a stereotactic head ring. Recent improvements in image-guidance systems have introduced the possibility of image-guided radiosurgery with nonrigid immobilization. We present data on the alignment accuracy and patient stability of a frameless image-guided system. ⋯ Frame-based and image-guided alignment accuracy in vitro was comparable for the system tested. In vivo tests showed a consistent trend in the difference of alignment in the anteroposterior direction, possibly due to torque to the ring and mounting system with frame-based localization. The mask system as used appeared adequate for patient immobilization.
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Int. J. Radiat. Oncol. Biol. Phys. · Jun 2009
Multicenter StudyToward submillimeter accuracy in the management of intrafraction motion: the integration of real-time internal position monitoring and multileaf collimator target tracking.
We report on an integrated system for real-time adaptive radiation delivery to moving tumors. The system combines two promising technologies-three-dimensional internal position monitoring using implanted electromagnetically excitable transponders and corresponding real-time beam adaptation using a dynamic multileaf collimator (DMLC). ⋯ We have developed and characterized a research version of a novel four-dimensional delivery system that integrates nonionizing radiation-based internal position monitoring and accurate real-time DMLC-based beam adaptation. This system represents a significant step toward achieving the eventual goal of geometrically ideal dose delivery to moving tumors.