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Publication Number
US-10576301-B2
Publication Date
2020-03-03
Expiration Date
Abstract
A fluorescing marker is used in order to mark (for example) a leaf of a multi-leaf collimator and/or the reference points within the field of view. The markers are illuminated with light tuned to cause the markers to fluoresce at a wavelength different to that of the illuminating light. The fluorescence is then detected by a camera. This method allows the image to be captured by the camera with increased contrast. Accordingly, the present invention provides a multi-leaf collimator for a radiotherapeutic apparatus, comprising at least one leaf having a fluorescent marker. The fluorescent marker will usually emit light of a wavelength longer than the incident light, allowing suitable filters to be provided in order to distinguish the light emitted by the markers. A suitable material for use in the fluorescent markers is ruby. The present invention also provides a radiotherapeutic apparatus comprising a multi-leaf collimator as defined above, and a camera arranged to view the fluorescent markers. A source of illumination for the fluorescent markers is ideally monochromatic, or nearly so. The camera can have a filter arranged to substantially prevent light of the wavelength emitted by the source of illumination from entering the camera, thereby improving the contrast of the image. The radiotherapeutic apparatus can also comprise a source of illumination that is optically co-located with a radiation source, to allow the radiation field that will be emitted to be checked visually by an operator. The co-located source is preferably substantially monochromatic, emitting substantially no light at the wavelength of the fluorescent markers. A filter can then be placed over an output of the radiotherapeutic apparatus, for blocking light of the wavelength of the fluorescent markers and thereby enhancing the contrast of the image that is taken of the fluorescent markers.
Core Innovation
The invention relates to a radiotherapeutic apparatus that includes a machine-vision system for locating and imaging fluorescent markers on a multi-leaf collimator. A multi-leaf collimator comprising a plurality of leaves collimates a beam of therapeutic radiation, and at least one leaf has a fluorescent marker. Fluorescence is stimulated by diffuse, substantially monochromatic light having a first wavelength delivered by a first light source.
The first light source has a position that is independent of the position of the source of the therapeutic radiation. Light having the first wavelength is filtered out at an output of the multi-leaf collimator, and a camera is arranged to view the fluorescent markers. The described approach separates stimulating illumination from fluorescence detection by using wavelength-selective filtering for image contrast.
The disclosed concept is supported by the described use of fluorescent markers and wavelength-selective filtering with a camera to enable machine vision of the markers during radiotherapy. Other embodiments specify wavelength relationships in which the fluorescent marker fluoresces at a wavelength longer than one or more illumination wavelengths, together with constraints intended to prevent light generated by the first light source from exiting the multi-leaf collimator.
Claims Coverage
The partial content includes three independent claims (clm-00001, clm-00014, clm-00018). Each claim centers on using a fluorescent marker on a multi-leaf collimator, stimulating fluorescence with diffuse substantially monochromatic light from a first light source at a first wavelength independent of the therapeutic radiation source position, filtering out the first wavelength, and viewing the markers using a camera.
Fluorescent marker on multi-leaf collimator with independent-stimulus illumination
A radiotherapeutic apparatus comprising a multi-leaf collimator having a fluorescent marker on at least one leaf, a first light source generating diffuse, substantially monochromatic light with a first wavelength for stimulating fluorescence in the fluorescent marker, wherein a position of the first light source is independent of a position of a source of the therapeutic radiation, a filter arranged over an output of the multi-leaf collimator for filtering out light having the first wavelength, and a camera arranged to view the fluorescent markers.
Radiotherapeutic radiation collimated with fluorescent-marker multi-leaf collimator and camera viewing
A method comprising generating a beam of therapeutic radiation, collimating the beam of therapeutic radiation using a multi-leaf collimator comprising a plurality of leaves, at least one leaf of the plurality of leaves having a fluorescent marker, generating diffuse, substantially monochromatic light having a first wavelength with a first light source for stimulating fluorescence in the fluorescent marker where a position of the first light source is independent of a position of a source of the therapeutic radiation, filtering out light having the first wavelength at an output of the multi-leaf collimator, and viewing the fluorescent markers using a camera.
Means for independent-stimulus fluorescence imaging with filtered wavelength removal
An apparatus comprising means for generating a beam of therapeutic radiation, means for collimating the beam of therapeutic radiation using a multi-leaf collimator with at least one leaf having a fluorescent marker, means for generating using a first light source diffuse, substantially monochromatic light having a first wavelength for stimulating fluorescence in the fluorescent marker wherein a position of the first light source is independent of a position of a source of the therapeutic radiation, means for filtering out light having the first wavelength at an output of the multi-leaf collimator, and means for viewing the fluorescent markers using a camera.
Across the independent claims, the coverage is focused on fluorescent markers associated with a multi-leaf collimator, stimulating fluorescence using diffuse substantially monochromatic light from a first light source whose position is independent of the therapeutic radiation source position, filtering out light having the stimulating first wavelength at an output of the multi-leaf collimator, and viewing the fluorescent markers using a camera. Dependent claims in the partial content further refine marker coverage, marker form examples, wavelength relationships for fluorescence, and constraints intended to prevent the first light source light from exiting the multi-leaf collimator.
Stated Advantages
Increased marker durability in harsh environments.
Reduced sensitivity to stray reflections and external lighting.
Elimination of constraints requiring optically identical light-source and camera positions.
Improved tolerance/assembly and potential reduced recalibration when replacing markers.
Documented Applications
Machine-vision imaging of fluorescent markers on a multi-leaf collimator during radiotherapy using a camera and wavelength-filtered illumination.
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