Abstract: The present invention describes a method enabling one to shield a device that measures weak biomagnetic signals from strong magnetic interference fields. The measurement sensors are provided with a feedback compensation loop, the difference signal of which is obtained from the measurement sensors themselves. As the actuator of the feedback function, one or more coils are responsible for eliminating, the external interference fields in the region of the sensors. Difference signals can be generated as a linear combination from the signals of two or more sensors. In the control logic, the SSS method can be used to numerically separate the biomagnetic signal being measured from the signals produced by the sources—compensation coils and interference sources—disposed outside the measurement region. The interference suppression can be enhanced by placing the assembly of sensors and the actuators within a magnetically shielding room.

Abstract: We propose to shape the leaf by the use of electro-chemical machining (ECM). ECM is a technique by which a blank is suspended within a mould, with a small gap therebetween. A conductive fluid is caused to flow through the gap, and a large electrical current is passed from the mould to the blank. The blank steadily erodes, dissolving into the fluid. The fluid should not provoke a reaction from the material of the blank, such as a surface oxide. Sodium Chloride solution is a common choice. The current that is passed can, if desired, be controlled to a profile that will affect the manner of erosion. Thus, the current profile can be a steady on/off current, or it can be pulsed. One known arrangement is for the current to rise to a peak, then fall to zero, followed by a brief reverse flow.

Abstract: A geometry item (such as a gantry arm or an MLC leaf) of a radiotherapeutic apparatus needs to be moved in an accurate manner. The effect of inertia introduces a potential inaccuracy. A radiotherapeutic apparatus is therefore disclosed, comprising a geometry item, a radiation source capable of emitting a beam of therapeutic radiation, and a control unit, the geometry item being moveable to adjust the geometry of the beam, the radiation source having a variable dose rate, and the control unit being arranged to cause variations in the speed of movement of the geometry item and to adjust the dose rate of the radiation source for a period of time after a change in the speed of the geometry item.

Abstract: The detected positioning error in a geometry item of a radiotherapy apparatus is generally passed to a transfer function for the system, which outputs a signal that dictates the radiation output. If the detected error is within certain limits then the radiation is permitted whereas outside those limits it is not permitted; this corresponds to a transfer function that is a simple two step function. We propose a transfer function having a result that is (a) substantially zero outside a preset error tolerance, (b) has a maximum result at a point within that tolerance, and (c) has a result that is between zero and that maximum over a range of error values that lie between (i) the error value corresponding to the maximum output and (ii) the preset error tolerance. This means that if an error grows towards (but does not exceed) the error tolerance, the output of the radiation source will reduce and allow time for the geometry item to correct its position.

Abstract: A mount for a radiotherapy apparatus comprises a cylindrical bearing surface to allow the mount to be supported in a rotatable manner, a housing extending from the bearing surface and having an extent in a direction along an axis of the cylindrical bearing surface, the mount having an axial through-hole which encompasses the axis of the cylinder, the housing having at least one opening communicating with the through-hole and extending in a direction transverse to the axis of the cylinder. This mount can be used as the basis for a number of different radiotherapy systems.

Abstract: A device is provided for fixation of equipment to the head of a patient during neurological diagnosis, therapy or surgery, comprising a ring-shaped frame having at least three fixation pins which are attachable against the skull of the patient with a contact force for fixation of the device thereto. At least one connecting means is positioned at a location where the frame has a minimum of displacement due to deformation of the frame when the fixation pins are tightened towards the skull, in order to allow fixation of equipment for diagnosis, therapy or surgery to the frame without they being distorted as a consequence of the deformation of the frame. The invention also relates to a method for fixation of the head of a patient by means of such a device.

Abstract: The present invention relates to a novel manner of measuring DC fields using a multi-channel MEG or MKG measuring instrument; and on the other hand, to a manner of eliminating from the measurement result the interference signals caused by the DC currents. The invention combines the monitoring system of a testee's movement and the method for motion correction of the measured signals so that the signals produced by the DC currents of a moving testee's are visible in the final measurement result as a static signal component in a conventional MEG or MKG measurement. In that case, in the measurement, it is not necessary to beforehand prepare oneself for measuring the DC fields.

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 present invention relates to a collision detecting device for a radiation treatment apparatus, comprising a radiation unit having an internal space, for directing radiation beams towards a radiological focus in the internal space for treatment of a target in a patient's body therein. The collision detecting device comprises a collision detecting unit being electrically conductive at least on its outer surface and having a size slightly smaller than the internal space of the radiation unit, so as to be insertable into the internal space and held in an electrically insulating manner in respect of the radiation unit by spacer elements. The outer electrically conductive surface is connectible to an electrical voltage supply in order to detect if the outer surface of the collision detecting unit abuts against the inside surface of the radiation unit. The invention also relates to a method for performing such collision detection.

Abstract: A patient support system comprises a base, an upstanding support, and a couch attached to the support and having a cantilever section extendable beyond the support; the support including a couch drive means to adjust the position of the couch relative to the support; further comprising a support drive means for translationally driving the support relative to the base in the direction of the cantilever section. This removes inaccuracies from patient position measurements that result from changes in the cantilever geometry during movement of the patient from a measuring position to a treatment position. The support drive means can be located in the base or in the support, and allows the patient support system as a whole to be translated, thereby permitting the patient to be moved into and out of an enclosed treatment area without affecting the vertical location of the patient.

Abstract: The present invention recognises and eliminates from a biomagnetic measurement signal interferences whose source is disposed in the direct vicinity of an object being measured. The invention utilises the SSS method that can be used to separate from one another the signals associated with the internal and external sources of a set of measurement sensors by calculating two series developments. The sources to be examined in the invention and disposed in the so-called intermediate space produce a component to both of the developments, and can, therefore, be detected by means of an analysis to be performed in a time domain. This division into components can be made using the Principal Component Analysis (PCA), the Independent Component Analysis (ICA) or the Singular Value Decomposition. Finally, the clarified interferences in the intermediate space can be eliminated from the measured signal using, for example, the linear algebraic orthogonal projection.

Abstract: The present invention relates to a device for fixation to a head of a patient during neurological diagnosis, therapy or surgery, in particular during MRI diagnosis. The device comprises at least one fixation pin for fixation to the head, a sleeve member (5) having an internal threaded through bore to at least partly receive and hold said fixation pin, and a pin support member for supporting said fixation pin and sleeve member. The sleeve member is exchangeable and provided in at least two different lengths in order to allow adaptation of the sleeve member to the size of the head to improve the fixation of the head and avoid the fixation pin to protrude beyond the outer boundary of the pin support member. The invention also relates to a method for fixation of a head.

Abstract: A multi-leaf collimator comprises an elongate leaf moveable in a longitudinal direction, and having an associated toothed rack driven by a pinion, wherein the rack is carried on an elongate actuator section, having a transversely extending link section, the leaf being connected to the link section and thereby being spaced from the actuator section. The pinion can thus be mounted on a shaft which is disposed transversely to the leaves of the array, and which passes between those leaves and their respective actuators. Some leaves can be driven via pinions mounted on shafts passing over the array, and other leaves can be driven via pinions mounted on shafts passing within the gaps between leaves and actuators. This means that twice the number of drive shafts can be fitted into the same length of array, thus either shortening the array or permitting more leaves and hence greater resolution. The drive mechanism can also be made as a separate unit.

Abstract: Methods for the registration of images typically assume that there are only two images, an assumption that is not always valid. By using the remaining images to obtain a choice of paths between two selected images, the transformation between the two can be determined with greater accuracy by averaging those paths. When averaging the paths, greater weight can be given to paths whose accuracy is known or reasonably believed to be greatest. Iteration of the process may be possible, where the available computation power is available.

Abstract: The present invention seeks to provide a radiotherapeutic apparatus that mitigates the various problems found in the techniques such as tomotherapy, IMAT, IMRT and the like. It provides a radiotherapeutic apparatus comprising a source of radiation whose output is collimated by a multi-leaf collimator, and a patient support, the source being rotateable around the support and the support being translatable along the axis of rotation, thereby to move the source helically relative to a patient on the support. The leaves of the MLC are preferably oriented orthogonal to the axis of rotation, to simplify computation of the dose distribution. The apparatus thus moves the patient on the patient support system along the axis of rotation, in the longitudinal direction. Thus, the device has an effectively unlimited treatable volume in the longitudinal direction and avoids the limitations of IMAT and IMRT techniques whilst enabling the use of thin MLC leaves to give a high longitudinal resolution.

Abstract: The co-registration of a volumetric ultrasound acquisition of the volume of interest with a magnetic resonance image allows the former to providing the basis for calculation of the dose distribution and the latter to provide the basis for target delineation and isocenter placement. The present invention therefore provides an apparatus for planning the radiotherapeutic treatment of a volume of tissue, comprising a sonographic apparatus for acquiring acoustic data relating to the volume, a means for reconstruction of an internal structure of the volume on the basis of the acoustic data, and a means for classification of the material type within that internal structure to one or more tissue types. A three-dimensional motion-tracking device for the sonographic device will assist. The sonographic device will typically be an ultrasound probe. The tissue type data can be passed to a dosage calculation means for determination of radiation dosage.

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: An apparatus, method and software module for selecting phase-correlated images from the output of a scanner such as a cone beam CT scanner operates by collapsing the images derived from the series from two dimensions to one dimension by summing the intensities of pixels along a dimension transverse to the one dimension, producing a further image from a composite of the one-dimensional images obtained from images in the series, analysing the further image for periodic patterns, and selecting from the series images having like phase in that periodic pattern. If desired, a plurality of reconstructions can be derived at different phases. The analysis of the further image for periodic patterns can include comparing the one-dimensional images therein, to identify a movement of features in that dimension. This allows (inter alia) the accurate determination of the breathing cycle in a patient and a concomitant improvement in the quality of CT scans by using phase-correlated images.

Abstract: The present invention discloses a joint structure between the wall elements of a light-weight magnetically shielded room. In the joint structure, the end of the aluminum plate of the element is stepped and its surface roughened. In addition to this, the aluminum plate is coated, for example, with tin to improve the electrical contact. The joint includes ? metal plates which are used to make a magnetic contact between the ? metal plates of the elements. The compression force achieved by means of bolts is transmitted to the joint by means of an aluminum moulding. The non-continuous compression force is balanced over the entire joint area by using presser rubbers. The joint structure is protected by means of supporting profiles which are used to electrically couple the thinner aluminum plate of the sandwich type wall element to the thinner aluminum plate of an adjacent element. The thinner aluminum plate and the supporting profile can also be coated, for example, with tin to improve the contact.

Abstract: The invention relates to a wall element for a magnetically shielded room and to a magnetically shielded room. The wall element comprises at least one first layer (1) which is formed of metal plate having a high electrical conductivity, and at least two layers, a second layer (2) and a third layer (3), which consist of metal plates having a high magnetic permeability. The layers (1, 2, 3) are superimposed one on top of another in surface contact with each other without any separating air gaps, so that each first layer (1) having a high electrical conductivity lies between each second (2) and third layers (3) having a high permeability substantially in surface contact with the second and third layers, the layers together forming a compact structure in which the product (?×?) of electrical conductivity (?) and permeability (?) is maximized so as to minimize the penetration depth of magnetic interference.