Abstract: A method of reducing a total number of beam segments in a dose distribution for a radiation therapy field is provided.

Abstract: An adaptive imaging method of monitoring intrafraction target motion during radiation therapy is provided that includes using a simultaneous Mega-Voltage (MV) imaging process and Kilo-Voltage (KV) imaging process to determine an initial 3D target position. 2D target position is monitored using the MV imaging process during a radiation therapy treatment delivery, and is in combination with an online-updated characterization of target motion that are disposed to estimate if the target has moved beyond a 3D threshold distance. The simultaneous MV imaging and KV imaging processes are for accurately determining a new 3D target position for intrafraction motion compensation and for further 2D imaging by the MV imaging process, where another simultaneous MV and KV imaging process is initiated when the target has potentially moved beyond the threshold distance as measured by the MV imaging process. The intrafraction target motion monitoring is achieved at the cost of ultralow patient imaging dose.

Abstract: A binary image reconstruction method is provided to identify metal objects in a computer tomography (CT) image. The method includes providing a suitably programmed computer, providing a CT image, where the CT image includes intensity data, and the suitably programmed computer is used to determine a first range of attenuation coefficient values and a second range of attenuation coefficient values in the intensity data, where when a difference between the first range of attenuation coefficient values and the second range of attenuation coefficient values is less than a pre-determined gradient threshold value, a boundary of a metal object in the CT image is determined.

Abstract: Real-time 3D tracking of anatomical positions during radiation therapy uses acquired image data from an MV treatment beam as it is rotated around the patient during arc radiotherapy treatment. The acquired image data and associated angular positions are computationally combined during the arc radiotherapy treatment to estimate in real time 3D positions of anatomical features of the patient, e.g., combining present image data and prior image data at earlier times. Supplementary image data from a kV imaging system may be acquired on an as-needed basis if MV position estimates indicate movement exceeding a predetermined threshold, and the supplementary kV image data combined with the acquired MV image data to improve an accuracy of the estimated 3D positions.

Abstract: The present invention provides a radiotherapy treatment apparatus that includes a treatment beam, a magnetic field disposed parallel collinear to the treatment beam, and a target that is disposed along the treatment beam. The treatment beam can be a charged particle beam, a proton beam, an electron beam, or a linear accelerator (Linac) beam. The magnetic field is from a magnetic resonance imager (MRI), a megavolt x-ray imager, or a kilovolt x-ray imager and is disposed to operate in coordination with operation of the treatment beam and to narrow the beam. The tumor is disposed to rotate with respect to the treatment beam and the magnetic field, or the treatment beam and the magnetic field are disposed to rotate up to 360° with respect to the target when mounted to a ring gantry. The apparatus can include a rotation angle dependent shim disposed to account for Earth's magnetic field.

Abstract: Disclosed is a self servo-writing disk drive that pre-programs a preamplifier to improve servo-writing characteristics in writing servo sectors to a disk. The disk drive implements operations including: writing servo sectors to define track bands according to sets of write setting values wherein the preamplifier adjusts write signals utilizing a set of write setting values for each track band; reading servo variable gain amplifier values from the tracks bands; selecting a set of write setting values associated with a minimum servo variable gain amplifier value; programming the preamplifier's write settings with the selected set of write setting values; and self-servo writing the disk with servo sectors utilizing the selected set of write setting values that are pre-programmed in the preamplifier.

Abstract: A general imaging scheme is proposed for applications of CBCT. The approach provides a superior CBCT image quality by effective scatter correction and noise reduction. Specifically, in its implementation of CBCT imaging for radiation therapy, the proposed approach achieves an accurate patient setup using a partially blocked CBCT with a significantly reduced radiation dose. The image quality improvement due to the proposed scatter correction and noise reduction also makes CBCT-based dose calculation a viable solution to adaptive treatment planning.

Abstract: A medical imaging-based system and method uses both kV and MV images captured during a treatment period for organ motion tracking. 3D geometric locations of internal features are computationally tracked as a function of time from internal features, such as natural biological features or implanted fiducials, which are computationally extracted from the captured kV and MV images. A partial information method allows 3D tracking to be maintained in the event that imaging information is temporarily not available.

Abstract: A method and system are disclosed for estimating internal position information of a target in real-time based on a single gantry-mounted x-ray imager and a respiratory signal. The x-ray imaging is done periodically to limit radiation dosage. Initial parameters for the estimation model are determined in a pre-treatment session using four dimensional computed tomography (4D CT) in combination with a respiratory signal acquired from the patient. The model parameters are updated during treatment based on the periodic x-ray image data and the respiratory signal.

Abstract: A method is provided for determining the positional accuracy of leaves of a multileaf collimator for delivering doses of radiation to a particular spatial location for treatment purpose. The method could be implemented as routine quality assurance check of the multileaf collimator leaf positioning errors. The method includes producing a first field and producing a second field, which is different from the first field. A dosimeter means is included for measuring a radiation dose difference or ratio between the first field and the second field at at least one spatial location. The dose difference or ratio is then used to determine the positional accuracy of the leaves by comparing with a known relationship between leaf positional errors and relative dosimeter outputs. The method provides a more simplified, accurate, efficient and reliable method over currently used methods.

Abstract: A general computer-implemented method and computer program for an independent MU or dose and fluence calculation of an intensity modulated photon field in intensity modulated radiation therapy (IMRT) is provided. The present invention provides for the verification MU or dose calculation in high dose regions or low dose regions. In general, the dose at an arbitrary spatial point is expressed as a summation of the contributions from all the beamlets in a treatment field, each modulated by a dynamic modulation factor. The verification of a low dose region is based on using the inverted field of the low dose region. The advantage of the present invention that it is an independent method and therefore generally applicable and useful irrespective of the type of leaf sequence algorithm and delivery machines. It provides an automated computer-implemented method or program that generalizes and simplifies dose verification in IMRT.

Abstract: A method is provided for interactive treatment planning of IMRT or other radiation modalities that employs non-uniform tuning or optimization. One aspect provides a voxel-dependent penalty scheme by varying the importance factor associated with a voxel, the prescription at the voxel, or the form of the penalty function at the voxel in a non-uniform manner. Another aspect provides the dose shape at a specified sub-volume tuned by varying the local importance factor(s) or the local prescription or the form/value of penalty function. Yet another aspect provides the use of a non-uniform penalty scheme (non-uniform importance factors, non-uniform prescription in one or more structures, or non-uniform form of the objective function). Still another aspect provides the method of pre-estimating the values of the voxel-specific importance factors using prior dosimetric knowledge of a given system.

Abstract: A general computer-implemented method and computer program for an independent MU or dose and fluence calculation of an intensity modulated photon field in intensity modulated radiation therapy (IMRT) is provided. The present invention provides for the verification MU or dose calculation in high dose regions or low dose regions. In general, the dose at an arbitrary spatial point is expressed as a summation of the contributions from all the beamlets in a treatment field, each modulated by a dynamic modulation factor. The verification of a low dose region is based on using the inverted field of the low dose region. The advantage of the present invention that it is an independent method and therefore generally applicable and useful irrespective of the type of leaf sequence algorithm and delivery machines. It provides an automated computer-implemented method or program that generalizes and simplifies dose verification in IMRT.

Abstract: A method is provided for determining the positional accuracy of leaves of a multileaf collimator for delivering doses of radiation to a particular spatial location for treatment purpose. The method could be implemented as routine quality assurance check of the multileaf collimator leaf positioning errors. The method includes producing a first field and producing a second field, which is different from the first field. A dosimeter means is included for measuring a radiation dose difference or ratio between the first field and the second field at at least one spatial location. The dose difference or ratio is then used to determine the positional accuracy of the leaves by comparing with a known relationship between leaf positional errors and relative dosimeter outputs. The method provides a more simplified, accurate, efficient and reliable method over currently used methods.

Abstract: A method for selecting an orientation of a treatment beam for intensity modulated radiation therapy based on analysis performed on a model of a patient geometry prior to the actual treatment includes a planning target volume (PTV) and the structures at risk. The method calls for assigning a tolerance parameter to the structures at risk, subdividing the treatment beam into beamlets, selecting a treatment parameter and selecting a set of orientations for the treatment beam and deriving a score for each of the orientations by weighting each of the beamlets so as to maximize the treatment parameter in the PTV while not exceeding the tolerance parameter in the structures at risk at each orientation. The derived scores are used to construct a scoring function to aid in the selection of one or more treatment beam orientations to be used during the actual intensity modulated radiation therapy.

Abstract: A method for selecting an orientation of a treatment beam for intensity modulated radiation therapy based on analysis performed on a model of a patient geometry prior to the actual treatment. The model of patient geometry includes a planning target volume (PTV) containing the object to be treated by radiation, e.g., a tumor, and the structure or structures at risk, such as internal organs, bone and/or tissue. The method calls for assigning a tolerance parameter to the structure or structures at risk, subdividing the treatment beam into beamlets, selecting a treatment parameter and selecting a set of orientations for the treatment beam and deriving a score for each of the orientations in the set by weighting each of the beamlets so as to maximize the treatment parameter in the PTV while not exceeding the tolerance parameter in the structure or structures at risk at each orientation.