Abstract: A radiotherapy system is configured to determine in vivo dose deposition of a radiotherapy treatment beam. The system includes the following components. A bi-planar magnetic resonance imaging (MRI) apparatus comprising a pair of spaced apart magnets. One of the magnets includes a hole proximal the centre thereof. A treatment beam source configured to generate a radiotherapy treatment beam. The treatment beam source is positioned to transmit the treatment beam through the hole in the magnet. A patient support configured to position a patient with the system so that a treatment target is proximal the treatment beam. A Positron Emission Tomography (PET) detector configured to obtain PET data of the treatment beam impacting the patient. The PET detector is positioned so that a transverse section of the patient that includes the treatment target lies between opposing portions of the PET detector.

Abstract: A magnetic resonance (MR)-radiotherapy (RT) hybrid system for treating a patient is disclosed. The MR-RT hybrid system comprises: an MR imaging (MRI) apparatus comprising bi-planar magnets configured to generate a magnetic field; a radiation source configured to supply a radiation beam to treat the patient; a gantry configured to couple the MR apparatus at a first end and the radiation source so that they can rotate in unison; a treatment support configured to support the patient; a motor configured to move the treatment support; and a controller. The controller comprises a processor and memory having stored thereon instructions, which when executed by the processor, cause the motor to move the treatment support in order to avoid collision between the MRI apparatus and the patient when the MRI apparatus is rotated. A method for positioning the treatment support within the MR-RT hybrid system is also disclosed.

Abstract: A magnetic resonance imaging (MRI) and radiation therapy system is described. The system has a magnet gantry, an MRI apparatus, a patient support system and a radiation source head. The magnet gantry is configured to rotate about a magnet gantry axis. The MRI apparatus is coupled to the magnet gantry. The radiation source head is coupled to the MRI apparatus via a radiation source arm. The radiation source head is configured to emit a treatment beam at varying angles with respect to an azimuthal gantry axis. A method for performing stereotactic radiosurgery (SRS) using a magnetic resonance (MR)-SRS is also described.

Abstract: A radiation therapy system includes a radiation source capable of generating a beam of radiation; a magnetic resonance imaging (MRI) apparatus comprising at least one radiofrequency detector coil; and an electrically grounded dielectric material between the radiation source and the radiofrequency detector coil for shielding the at least one radiofrequency detector coil from the beam of radiation. Also disclosed is a radiofrequency detector coil for a magnetic resonance imaging (MRI) apparatus sheathed at least in part by a dielectric material that is adapted to be electrically grounded.

Abstract: A magnetic resonance (MR)-radiotherapy (RT) hybrid system for treating a patient is disclosed. The MR-RT hybrid system includes a radiation source for supplying a radiation beam to treat the patient and an MR imaging (MRI) apparatus for generating a divergent gradient field shaped to match a divergent geometry of the radiation beam of the radiation source.

Abstract: A magnetic resonance (MR)-radiotherapy (RT) hybrid system for treating a patient is disclosed. The MR-RT hybrid system comprises: an MR imaging (MRI) apparatus comprising bi-planar magnets configured to generate a magnetic field; a radiation source configured to supply a radiation beam to treat the patient; a gantry configured to couple the MR apparatus at a first end and the radiation source so that they can rotate in unison; a treatment support configured to support the patient; a motor configured to move the treatment support; and a controller. The controller comprises a processor and memory having stored thereon instructions, which when executed by the processor, cause the motor to move the treatment support in order to avoid collision between the MRI apparatus and the patient when the MRI apparatus is rotated. A method for positioning the treatment support within the MR-RT hybrid system is also disclosed.

Abstract: A magnetic resonance imaging (MRI) and radiation therapy system is described. The system comprises a magnet gantry, an MRI apparatus, a patient support system and a radiation source head. The magnet gantry is configured to rotate about a magnet gantry axis. The MRI apparatus is coupled to the magnet gantry. The radiation source head is coupled to the MRI apparatus via a radiation source arm. The radiation source head is configured to emit a treatment beam at varying angles with respect to an azimuthal gantry axis. A method for performing stereotactic radiosurgery (SRS) using a magnetic resonance (MR)-SRS is also described.

Abstract: A radiotherapy system is configured to determine in vivo dose deposition of a radiotherapy treatment beam. The system includes the following components. A bi-planar magnetic resonance imaging (MRI) apparatus comprising a pair of spaced apart magnets. One of the magnets includes a hole proximal the centre thereof. A treatment beam source configured to generate a radiotherapy reatment beam. The treatment beam source is positioned to transmit the treatment beam through the hole in the magnet. A patient support configured to position a patient with the system so that a treatment target is proximal the treatment beam. A Positron Emission Tomography (PET) detector configured to obtain PET data of the treatment beam impacting the patient. The PET detector is positioned so that a transverse section of the patient that includes the treatment target lies between opposing portions of the PET detector.

Abstract: A magnetic resonance (MR)-radiotherapy (RT) hybrid system for treating a patient is disclosed. The MR-RT hybrid system includes a radiation source for supplying a radiation beam to treat the patient and an MR imaging (MRI) apparatus for generating a divergent gradient field shaped to match a divergent geometry of the radiation beam of the radiation source.

Abstract: A radiation therapy system comprises a radiation source generating a beam of radiation and a magnetic resonance imaging apparatus. An interface acts between the radiation source and the MRI apparatus that permits irradiation to be performed simultaneously with imaging. The MRI apparatus and radiation source are coupled such that the system can be used in a rotation mode whereby the radiation source can irradiate a subject from basically any angle without reducing MRI image quality.

Abstract: A computer-implemented method is provided for reducing artifacts in an MRI image as a result of radiation induced current in collector coils of an MRI apparatus. The method comprises the following steps. Selecting a plurality of pixels in a k-space image prior to generation of the MRI image. Analyzing each of the plurality of selected pixels to determine whether a pixel intensity is greater than a predefined global threshold. For each pixel having pixel intensity greater than the predefined global threshold, determining whether the pixel lies within a signal region of the k-space image or outside of the signal region of the k-space image. For each pixel that lies outside of the signal region, modifying the pixel intensity to be similar to a background pixel intensity, thereby creating a modified k-space image. Generating the MRI image based on the modified k-space image. A non-transitory computer readable medium and a radiation therapy system configured to implement the method are also provided.

Abstract: A magnetic resonance (MR)-radiotherapy (RT) hybrid system for treating a patient is disclosed. The MR-RT hybrid system comprises: an MR imaging (MRI) apparatus comprising bi-planar magnets configured to generate a magnetic field; a radiation source configured to supply a radiation beam to treat the patient; a gantry configured to couple the MR apparatus at a first end and the radiation source so that they can rotate in unison; a treatment support configured to support the patient; a motor configured to move the treatment support; and a controller. The controller comprises a processor and memory having stored thereon instructions, which when executed by the processor, cause the motor to move the treatment support in order to avoid collision between the MRI apparatus and the patient when the MRI apparatus is rotated. A method for positioning the treatment support within the MR-RT hybrid system is also disclosed.

Abstract: Disclosed herein is a magnet assembly that includes at least two magnets arranged in a fixed spaced relationship with one another thereby to define a space between the magnets that encompasses an imaging volume. Each of the magnets produces a variety of magnetic field strengths across inward-facing surfaces thereof that, in combination, produce an acceptably homogeneous magnetic field in the imaging volume. Also disclosed is a method of defining a magnetic field for an imaging volume. The method comprises generating an initial model of a magnet assembly; estimating a magnetic field for the imaging volume based on the model; calculating deviation between the estimated magnetic field and a target magnetic field for the imaging volume; and updating the model to reduce the deviation by modifying the magnet assembly to produce a variety of magnetic field strengths that, in combination, produce substantially the target magnetic field in the imaging volume.

Abstract: A radiation therapy System comprises a magnetic resonance imaging (MRI) apparatus and a linear accelerator capable of generating a beam of radiation. The linear accelerator is immersed in and oriented with respect to the MRI magnetic field to expose the linear accelerator to magnetic force that directs particles therein along a central axis thereof.

Abstract: A computer-implemented method is provided for reducing artefacts in an MRI image as a result of radiation induced current in collector coils of an MRI apparatus. The method comprises the following steps. Selecting a plurality of pixels in a k-space image prior to generation of the MRI image. Analysing each of the plurality of selected pixels to determine whether a pixel intensity is greater than a predefined global threshold. For each pixel having pixel intensity greater than the predefined global threshold, determining whether the pixel lies within a signal region of the k-space image or outside of the signal region of the k-space image. For each pixel that lies outside of the signal region, modifying the pixel intensity to be similar to a background pixel intensity, thereby creating a modified k-space image. Generating the MRI image based on the modified k-space image. A non-transitory computer readable medium and a radiation therapy system configured to implement the method are also provided.

Abstract: A radiation therapy System comprises a magnetic resonance imaging (MRI) apparatus and a linear accelerator capable of generating a beam of radiation. The linear accelerator is immersed in and oriented with respect to the MRI magnetic field to expose the linear accelerator to magnetic force that directs particles therein along a central axis thereof.

Abstract: A radiation therapy treatment method comprises imaging a subject and simulating four-dimensional aspects of radiotherapy. A treatment plan based on the simulation is generated to permit real-time, three-dimensional dose reconstruction at the time of treatment. The simulation and treatment plan are used during treatment fractions to achieve real-time image guidance.

Abstract: Disclosed herein is a magnet assembly that includes at least two magnets arranged in a fixed spaced relationship with one another thereby to define a space between the magnets that encompasses an imaging volume. Each of the magnets produces a variety of magnetic field strengths across inward-facing surfaces thereof that, in combination, produce an acceptably homogeneous magnetic field in the imaging volume. Also disclosed is a method of defining a magnetic field for an imaging volume. The method comprises generating an initial model of a magnet assembly; estimating a magnetic field for the imaging volume based on the model; calculating deviation between the estimated magnetic field and a target magnetic field for the imaging volume; and updating the model to reduce the deviation by modifying the magnet assembly to produce a variety of magnetic field strengths that, in combination, produce substantially the target magnetic field in the imaging volume.

Abstract: A radiation therapy system includes a radiation source capable of generating a beam of radiation; a magnetic resonance imaging (MRI) apparatus comprising at least one radiofrequency detector coil; and an electrically grounded dielectric material between the radiation source and the radiofrequency detector coil for shielding the at least one radiofrequency detector coil from the beam of radiation. Also disclosed is a radiofrequency detector coil for a magnetic resonance imaging (MRI) apparatus sheathed at least in part by a dielectric material that is adapted to be electrically grounded.

Abstract: A radiation therapy treatment method comprises imaging a subject and simulating four-dimensional aspects of radiotherapy. A treatment plan based on the simulation is generated to permit real-time, three-dimensional dose reconstruction at the time of treatment. The simulation and treatment plan are used during treatment fractions to achieve real-time image guidance.