Abstract: Calibration of a radiation therapy system comprising a radiation unit with a fixed focus point, a fixation unit for fixing a treatment volume in a patient, and a positioning system. The positioning system comprises a fixed framework, a movable carriage for carrying and moving the entire patient, motor(s), a control system for controlling the motor(s), and at least one engagement point for releasably mounting the fixation unit in fixed engagement with the positioning system. A fixation unit coordinate system defined in relation to the fixation unit is provided. Linearity errors for the motional axes of the carriage and the angular offset between the motional axes and the coordinate system is determined, whereby the relationships between the axes of the coordinate system and the motional axes of the positioning system are determined.

Abstract: The invention relates to an adapter (5) for a fixation pin (2) of the type which is adapted for fixating a supporting structure to a bony structure of a human or animal body part, and which is provided with a shank portion (4). The adapter (5) comprises a sharp-pointed tip (7), for penetration into the bony structure of the body part, and an engagement formation (8) for removable connection to an inner end of said shank portion (4). The invention also relates to a fixation pin and a method for fixating a supporting structure to a human or animal body part.

Abstract: The present invention therefore provides a method of treating the surface of an item for a radiotherapy apparatus, comprising the steps of machining into a planar reflective surface of the item a stepped profile, each step having a first surface angled to the planar reflective surface such that, in use, the first surface reflects light incident on the planar reflective surface away from the isocentre of the radiotherapy apparatus and a second surface angled with respect to the planar reflective surface and the first surface such that, in use, the second surface is shadowed from light incident on the planar reflective surface by the first surface, the steps having a depth which does not exceed 2.15% of the total depth of the item.

Abstract: A method for interpreting the current distribution of an object being measured using basis vector components calculated from the measured signals. The components in question have been so selected that they describe the features, as independent as possible, of the current distribution being examined, which enhances the computation and makes it more accurate. This is achieved by converting the measured signals into a more natural form from the standpoint of the current distribution while totally eliminating the signals associated with the external interferences. After the conversion, the source modeling is performed in an optimal manner using the basis vector components of the signal space instead of the actual measurement signals. One substantial feature of the invention is that after the conversion, the source model need not be regularized any more.

Abstract: The invention relates to a device for examination of the straightness of diagnostic and therapeutic needles (11), of the kind which are, with a high grade of accuracy, adapted for selection of samples from, injection of therapeutic preparations into or mounting at target areas positioned deep in tissue. The device comprises a support (1) in which a needle (11) to be examined is rotatably mountable by means of at least one holding fixture (6), such that the needle being rotatable in the support for allowing examination of the needle in all directions. The invention also relates to a method for performing such an examination.

Abstract: Artifacts in the reconstructed volume data of cone beam CT systems can be removed by the application of respiration correlation techniques to the acquired projection images. To achieve this, the phase of the patients breathing is monitored while acquiring projection images continuously. On completion of the acquisition, projection images that have comparable breathing phases can be selected from the complete set, and these are used to reconstruct the volume data using similar techniques to those of conventional CT. Any phase can be selected and therefore the effect of breathing can be studied. It is also possible to use a feature in the projection images such as the patient's diaphragm to determine the breathing phase. This feature in the projection images can be used to control delivery of therapeutic radiation dependent on the patient's breathing cycle, to ensure that the tumor is in the correct position when the radiation is delivered.

Abstract: A linear accelerator comprises a series of accelerating cavities, adjacent pairs of which are coupled via coupling cavities, in which at least one coupling cavity comprises a rotationally asymmetric element that is rotateable thereby to vary the coupling offered by that cavity. A control means for the accelerator is also provided, adapted to control operation of the accelerator and rotation of the asymmetric element, arranged to operate the accelerator in a pulsed manner and to rotate the asymmetric element between pulses to control the energy of successive pulses. A beneficial way of doing so is to rotate the asymmetric element continuously during operation of the linear accelerator. Then, the control means need only adjust the phase of successive pulses so that during the brief period of the pulse, the asymmetric element is “seen” to be at the required position.

Abstract: A linear accelerator comprises a series of accelerating cavities, adjacent pairs of which are coupled via coupling cavities, in which at least one coupling cavity comprises a rotationally asymmetric element that is rotateable thereby to vary the coupling offered by that cavity. A control means for the accelerator is also provided, adapted to control operation of the accelerator and rotation of the asymmetric element, arranged to operate the accelerator in a pulsed manner and to rotate the asymmetric element between pulses to control the energy of successive pulses. A beneficial way of doing so is to rotate the asymmetric element continuously during operation of the linear accelerator. Then, the control means need only adjust the phase of successive pulses so that during the brief period of the pulse, the asymmetric element is “seen” to be at the required position.

Abstract: A multi-leaf collimator is disclosed which alleviates the problems of inter-leaf leakage and pixellation. The collimator comprises a first multi-leaf collimator set, a second multi-leaf collimator set at an acute angle to the first, and a third multi-leaf collimator set at an acute angle to the second. Each multi-leaf collimator set will usually include a pair of leaf banks mutually opposed to each other. The acute angle between the first and the second multi-leaf collimator set is preferably the same as the acute angle between the second and the third set. A suitable angle is about 60°.

Abstract: A radiotherapy apparatus comprises a source of therapeutic radiation adapted to emit radiation along a therapeutic beam axis a source of diagnostic radiation adapted to emit radiation along a diagnostic beam axis, and a detector therefor, the two sources being rotateable in unison about a common axis intersecting with the therapeutic beam axis and the diagnostic beam axis; and a control unit arranged to move the therapeutic source to a first position by rotation thereof, activate the therapeutic source thereby to provide a first dose segment, de-activate the therapeutic source, rotate the sources together while the diagnostic source is active and while acquiring images from the detector, and re-activate the therapeutic source thereby to provide a second dose segment. A corresponding operation method is also disclosed, together with a reconstruction module.

Abstract: A radiation therapy device and a method of changing the spatial dose distribution surrounding a focus are disclosed. A subset of radioactive sources in a source carrier arrangement is displaceable relatively to collimator passage inlets, while the rest of the sources are fixed relatively to said collimator passage inlets.

Abstract: A method of automatically improving the usability of a medical picture is disclosed. An input medical picture, comprising an array of intensity data, is improved by automatically controlling at least one intensity parameter, such as brightness or intensity, in order to increase the entropy of at least a part of the array of intensity data. Hereby, a remarkable improvement in the intensity resolution of various parts, especially in soft tissue, is achieved.

Abstract: A radiation therapy device and a method of changing the spatial dose distribution surrounding a focus are disclosed. At least a subset of the radioactive sources in a source carrier is linearly displaceable relatively to at least a subset of collimator passage inlets, or vice versa.

Abstract: A radiation therapy/surgery device optimised to meet the needs of the Neurosurgeon is provided, i.e. one for the treatment of tumours in the brain. It combines the qualities of a good penumbra and accuracy, simple prescription and operation, together with high reliability and minimal technical support. The device comprises a rotateable support, on which is provided a mount extending from the support out of the plane of the circle, and a radiation source attached to the mount via a pivot, the pivot having an axis which passes through the axis of rotation of the support, the radiation source being aligned so as to produce a beam which passes through the co-incidence of the rotation axis and the pivot. It will generally be easier to engineer the apparatus if the rotateable support is planar, and more convenient if the rotateable support is disposed in an upright position. The rotation of the rotateable support will be eased if this part of the apparatus is circular.

Abstract: An optimization method for a fluence pattern to be provided via a radiotherapeutic apparatus comprising a multi-leaf collimator comprises an iteration of a progressive solution (such as a gradient approach) of the fluence profile, at least some iterations including a weighted penalty function which varies between solutions favored by the collimator design and solutions not so favored, later iterations including the penalty function at a greater weight. Thus, the penalty function represents locally preferred solutions derived from the constraints of the multi-leaf collimator (MLC). As the iteration progresses, the greater weight assigned to the penalty function drives the method towards a solution which is possible given the MLC constraints. However, the lesser weight attached in the early stages of the iteration allows the method to settle towards a genuinely preferred solution.

Abstract: A patient table has a removable end portion. This portion can thus be detached and replaced with an alternative end portion having a different shape, ideally having apertures in the areas where the beam requires access. This allows a wider range of shapes to be provided than can be achieved using configurable tables such as those noted above, whilst maintaining the mechanical strength required of the table. The parts of the table can be attached in a variety of ways. A preferred means of joining the two parts is to provide at least two engagement sites for mutual inter-engagement on each section, with the engagement sites of each part being spaced along the length thereof, the first engagement site closest the end of the respective section being adapted to engage on the top side thereof and the second engagement site more distant from the end being adapted to engage on the underside thereof.

Abstract: A radiation therapy device and a method of changing the spatial dose distribution surrounding a focus are disclosed. At least a subset of the radioactive sources in a source carrier is linearly displaceable relatively to at least a subset of collimator passage inlets, or vice versa.

Abstract: A method of providing with precision a number of long and narrow through holes (11) in a body (1) made of a high-density material. The body (1) is made in the form of a number of partial bodies (2, 2′, 2″), which are arranged close to each other and from the body (1). Each partial body (2, 2′, 2″) is defined by an outer surface (5), which is part of the outer surface of the entire body (1), an inner surface (6), which is part of the inner surface of the entire body (1), as well as a pair of boundary surfaces (7, 8), which extend from the outer surface (5) to the inner surface (6). Holes (11) are produced by machining at least one of the bounding surfaces (7, 8) adjacent partial bodies (2′, 2″). Each hole (11) extends from the outer surface (5) to the inner surface (6) along said at least one boundary surface (7, 8). The thus machined partial bodies (2, 2′, 2″) are fixedly attached to each other.

Abstract: A radiation therapy device and a method of changing the spatial dose distribution surrounding a focus are disclosed. A subset of radioactive sources in a source carrier arrangement is displaceable relatively to collimator passage inlets, while the rest of the sources are fixed relatively to said collimator passage inlets.

Abstract: A radiotherapy apparatus comprises a source of therapeutic radiation, a source of imaging radiation and a two-dimensional imager for the imaging radiation, a computing means for preparing tomography data from the output of the imager, the therapeutic source being controllable on the basis of feedback from the tomography data, wherein the computing means is arranged to prepare a plurality of intersecting sectional views from the output of the imager, akin to a portal image but with better contrast and the detail of a section rather than that of a projection. This is easier to interpret and visualise a series of sectional than a three dimensional view. Pixels of the images are the result of averaging a plurality of voxels arranged transverse to the section, typically orthogonal and linear. Typically, good results can be achieved using between 5 and 20 voxels. About 10 is suitable, ie between 7 and 15. There is a ideally a display means for showing the sectional views to an operator.