Elekta Ab (publ)

Elekta, Inc.

The Institute of Cancer Research

Elekta Ab

David Anthony Roberts

Kevin J Brown

Virgil Matthew Willcut

Martin Broad

Janusz Harasimowicz

Martin Sell

Maria Giulia Thompson

Julian Byrne

Vibeke Nordmark Hansen

Philip Mark Evans

John Allen

Christopher Charles Knox

Mark Strangeman

Peter Doherty

Jill Stief

Neil Winchester

Armin Fuerst

David Mills

Begoña Vivas-Maiques

Stephen Towe

Kevin John Brown

A method of operating a radiotherapy system mounted on a gantry surrounding a magnetic resonance imaging system is provided, the radiotherapy system comprising a radiotherapy beam generator, and a radiotherapy imaging system, wherein the gantry is arranged to rotate the radiotherapy beam generator around the magnetic resonance imaging system. The method comprises obtaining a reference image, the reference image including a predetermined feature of the magnetic resonance imaging system located near the radiotherapy imaging system; rotating the gantry relative the magnetic resonance imaging system; obtaining a second image, the second image including the predetermined feature of the magnetic resonance imaging system located near the radiotherapy imaging system; and determining changes in the relative positions of the radiotherapy beam generator, the radiotherapy imaging system, and the magnetic resonance imaging system based on differences in the position of the predetermined feature in the reference image and in the further image.

Methods and systems for checking alignment of components of a radiotherapy system

Apparatus for measuring radiation beam energy output from a radiation beam source, comprising a first beam energy sensor at a first distance from the radiation beam source along the radiation beam axis; a second beam energy sensor located at a second distance from the radiation beam source along the radiation beam axis; and an energy absorbing layer, for example a layer that removes a part of the low energy content of the beam or a layer that absorbs at least 1% of the beam energy, located between the first and second sensors, and positioned such that radiation passing through the first sensor also passes through the energy absorbing layer before entering the second sensor.

Method and apparatus for beam energy measurement

A method of determining the shape of a radiation beam of a radiotherapy system at a treatment position, the system comprising a radiation source and a multi-leaf collimator disposed between the radiation source and the treatment position. The multi-leaf collimator includes an array of moveable leaves positioned to intersect and block parts of the radiation beam to define the shape of the radiation beam at the treatment position. The leaves of a group are aligned such that the planes of the leaves in that group converge at a point displaced laterally from the radiation source. The method includes, for each leaf in the array positioned to intersect the radiation beam, determining a projected width with respect to the radiation beam, the projected width being greater than the thickness of the respective leaf, and using the projected leaf width to determine the shape of the radiation beam at the treatment position.

Methods and systems for determining the shape of a radiotherapy beam

A system or use with a radiotherapy system includes a scanner for producing images of at least one object within an imaging volume, a radiotherapy apparatus including a source of therapeutic radiation adapted to deliver a beam of radiation into the at least one object, a treatment planning system for controlling the source so as to deliver radiation in accordance with a predetermined plan for treating a patient and with the images of the at least one object, and at least one device within and/or adjacent to the imaging volume. The at least one device comprises at least one first marker which is visible to the scanner and at least one MR second marker which is visible to an MR scanner. The system further comprises a database containing data including the markers associated with the at least one device and at least its geometric and density characteristics.

Use of ancillary devices/accessories in radiotherapy systems

A collimator for a radiotherapy apparatus, comprising a block of isolation-attenuating material having a front face forming the leading edge of tie block and at least one main rear face defining the trailing edge of the block, in which the or each rear face is substantially planar in the direction of the depth of the block and non-parallel to the front face. The collimator may form part of a radiotherapy apparatus, and methods of operation of such apparatus are described.

Collimator for radiotherapy apparatus

A method of aligning the radiation beam in a radiotherapy system comprising a source for producing a beam of radiation and an imaging device for imaging from the beam, both mounted to be rotatable about an axis, a fiducial phantom between the source and imaging device, the method comprising: rotating the beam and imaging device in a trajectory about the axis while obtaining images of the fiducial phantom from a plurality of different angles, at least one image including a feature of the imaging apparatus, adjusting the trajectory of the source relative to that feature to position the isocenter substantially in the center of the volume, determining from each image of the fiducial phantom the position of the source at the rotational position the image was obtained, and calculating the center of rotation of the positions of the source to define the isocenter of the system.

Radiotherapy beam alignment with fiducial phantom imaging

Embodiments of the present invention provide markers, phantoms, and associated methods of calibration which are suitable for use in both magnetic resonance imaging and radiographic imaging systems. A marker includes a first marker component having a first hydrogen proton density and a first mass density; and a second marker component having a second hydrogen proton density different than the first hydrogen proton density, and a second mass density different than the first mass density. The first marker component and the second marker component are non-magnetic.

Markers, phantoms and associated methods for calibrating imaging systems

A collimator for a radiotherapy apparatus comprising a block of radiation-attenuating material having a front face forming the leading edge of the block and at least one main rear face defining the trailing edge of the block, in which the least one main rear face has a material disposed thereon and is non-parallel to the front face. The collimator may form part of a radiotherapy apparatus, and methods of operation of such apparatus are described.

A collimator for a radiotherapy apparatus, comprising a block of radiation-attenuating material having a front face forming the leading edge of the block and at least one main rear face defining the trailing edge of the block, in which the or each rear face is substantially planar in the direction of the depth of the block and non-parallel to the front face. The collimator may form part of a radiotherapy apparatus, and methods of operation of such apparatus are described.

The present invention provides a radiotherapy apparatus for applying therapeutic radiation to a target region of a patient, comprising a patient support, a source of radiation, a collimator comprising a plurality of leaves, a sensing system and control circuitry. The position of a target region is determined and resolved into two components orthogonal to the radiation beam axis. One component is assigned to the patient support, and the other to the collimator leaves, such that movement of the target region is compensated for and the radiation beam intersects is correctly targeted.

Radiotherapy apparatus configured to track a motion of a target region using a combination of a multileaf collimator and a patient support

It is desirable to achieve a co-incident investigative kV source for a therapeutic MV source&#x2014;a so-called 'beams-eye-view' source. It has been suggested that bremsstrahlung radiation from an electron window be employed; we propose a practical structure for achieving this which can switch easily between a therapeutic beam and a beam-eye-view diagnostic beam capable of offering good image resolution. Such a radiation source comprises an electron gun, a pair of targets locatable in the path of a beam produced by the electron gun, one target of the pair being of a material with a lower atomic number than the other, and an electron absorber insertable into and withdrawable from the path of the beam. In a preferred form, the electron gun is within a vacuum chamber, and the pair of targets are located at a boundary of the vacuum chamber. The lower atomic number target can be Nickel and the higher atomic number target Copper and/or Tungsten. The electron absorber can be Carbon, and can be located within the primary collimator, or within one of a plurality of primary collimators interchangeably locatable in the path of the beam. Such a radiation source can be included within a radiotherapy apparatus, to which the present invention further relates. A flat panel imaging device for this source can be optimised for low energy x-rays rather than high energy; Caesium Iodide-based panels are therefore suitable.

Radiotherapy apparatus

X-ray apparatus comprises a linear accelerator adapted to produce a beam of electrons at one of at least two selectable energies and being controlled to change the selected energy on a periodic basis, and a target to which the beam is directed thereby to produce a beam of x-radiation, the target being non-homogenous and being driven to move periodically in synchrony with the change of the selected energy. In this way, the target can move so that a different part is exposed to the electron beam when different pulses arrive. This enables the appropriate target material to be employed depending on the selected energy. The easiest form of periodic movement for the target is likely to be a rotational movement.

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East Grinstead, United Kingdom

David Anthony Roberts