105 results about "Calibration phantom" patented technology

A method for geometric calibration of a CT scanner, including, for each row of at least one row of detector cells, establishing a complete geometric description of the CT scanner, including at least one unknown geometric parameter, establishing a description of a forward projection function using the complete geometric description, acquiring actual projection coordinates of a calibration phantom placed in a scanning field of view (SFOV) on a current row of detector cells and corresponding to a plurality of angles, acquiring calculated projection coordinates of the calibration phantom on the current row of detector cells and corresponding to the plurality of angles using the description of the forward projection function, and acquiring a calibrated value for the at least one unknown geometric parameter by evaluating the at least one unknown geometric parameter based on the acquired actual projection coordinates and calculated projection coordinates via a nonlinear least square fitting algorithm.

In a registration method for navigation-guided medical interventions using a position acquisition system, an X-ray device and an X-ray calibration phantom having X-ray-positive marks, the coordinates of marks of the X-ray calibration phantom that are present in the measurement volume of the X-ray device and imaged in the reconstructed volume are determined in a coordinate system allocated to the measurement volume of the X-ray device) and in a coordinate system allocated to the position acquisition system. The coordinate transformation between the coordinate system allocated to the measurement volume and the coordinate system allocated to the position acquisition system is determined on the basis of the coordinates of the X-ray-positive marks in the coordinate system allocated to the measurement volume and on the basis of the coordinates of the X-ray-positive marks in the coordinate system allocated to the position acquisition system.

A hybrid calibration method uses an calibration phantom (exterior reference) scanned simultaneously with the patient, and one or more known tissues of the subject (interior reference) to create a hybrid calibration reference that improves the measurement of tissue densities throughout the body. In addition, the calibration method is used to quantitatively define boundaries of tissue and organs for more accurate measurements of lengths, areas and volumes. Another aspect of the invention uses the calibrated images to quantitatively preset absolute window / levels for filming and image display, which provides standardized viewing for diagnostic purposes.

The invention provides calibration method, device and calibration phantom of the geometric parameters in a CT (computer tomography) system. In the method, the calibration phantom is placed on a rotary table positioned between a light source and a detector, the calibration phantom comprises a calibration plate, as well as a small ball A and a small ball B which are arranged on the calibration plate, the calibration phantom is rotated for a circle along with the rotary table, and a center point coordinates of projection images of the small ball A and the small ball B are collected by the detector; the coordinate of an intersection point of a projective point line of projection ellipses of the small ball A and the small ball B is calculated and obtained according to the center point coordinates of the projection images and and the center coordinates of the projection ellipses of the small balls, and the torsion angle of the detector, the distance from the light source to the detector, the projection center point coordinate of the light source on a imaging plane, the swinging angle of the detector and the distance from the light source to the rotary table can be calculated based on the coordinate of the intersection point of the projective point line and a elliptic equation. The invention can calibrate a plurality of parameters, and can sufficiently meet the requirement of subsequent CT image correction.

A mutually calibrated magnetic imaging array system is described. The system includes a non-target magnetic source rigidly attached to a magnetometer, and an attached control unit to measure and adjust several parameters of a magnetic imaging array. A non-target magnetic field source is used to generate a well-defined and distinguishable spatial magnetic field distribution. The source is rigidly attached directly to a magnetometer, while the relative positions of the magnetometers are unknown. The magnetic imaging array is used to measure the strength of the non-target source magnetic fields and the information is used to calibrate several parameters of the array, such as, but not limited to, effective magnetometer positions and orientations with respect to each other and cross-talk between the magnetometers. The system, and method described herein eliminates the need for a separate calibration phantom.

The invention relates to a calibration phantom for calibrating geometric parameters in a CT (Computed Tomography) system. The calibration phantom comprises two same calibration plates which are arranged in parallel, and pellets, wherein the calibration plates are correspondingly provided with a plurality of same small holes respectively; and at least four pellets are arranged in the small holes in the calibration plates respectively. The invention relates to a calibration device for calibrating geometric parameters in a CT system. The calibration device comprises a CT system and the calibration phantom, wherein the CT system consists of a light source, a rotary platform and a detector; and the calibration phantom is vertically placed on the rotary platform between the light source and the detector. Furthermore, the invention further provides a calibration method for calibrating geometric parameters in a CT system. According to the calibration device and the calibration method, all seven geometric parameters of the CT system can be calibrated simultaneously by only performing one-time projection on the calibration phantom, so that operation is easy, and subsequent image correction of the CT system is met greatly.

It is possible that at a predetermined position of the imaging components of a radiographic imaging system the object is not fully viewed. The object can be a calibration phantom, which means that it is not possible to directly determine an imaging rule with the aid of the calibration phantom at this position of the imaging components. According to the invention, an imaging of the calibration phantom at a different position takes place and an imaging rule for this position is determined. This is then converted, provided a movement parameter is known which describes the movement from the position with the record of the calibration phantom to a different position. The imaging rule obtained in this way can be further improved, e.g. with the aid of a recording of the calibration phantom from the position in question, including if the calibration phantom is not completely imaged.

A registration method and an apparatus for navigation-guided interventions employing an X-ray device and a position acquisition system and avoid the use of patient-associated markers. By means of a defined arrangement of a carrying arm proceeding from a support mount at the X-ray device and a defined arrangement of an X-ray calibration phantom at the carrying arm, the coordinate transformation between a coordinate system allocated to the support mount and a coordinate system allocated to the X-ray calibration phantom is known. On the basis of the acquisition and evaluation of 2D projections of the X-ray calibration phantom with the X-ray device, a coordinate transformation between the coordinate system allocated to the support mount and a coordinate system allocated to a measurement volume of the X-ray device is produced. By arranging a device detectable by the position acquisition system at the support mount, a coordinate transformation between the coordinate system allocated to the measurement volume and a coordinate system allocated to the calibration phantom is determined for the navigation.

A calibration phantom for quality assurance of an image-based radiotherapy apparatus The calibration phantom includes a body comprising a cylindrical acryl member having a predetermined diameter, the body having a center hole at a center axis thereof and a plurality of through-holes in outer circumferential portions thereof at a predetermined interval from the center hole; round stick-type density bars inserted into corresponding through-holes of the body and made of materials each with different densities; an acrylic cover detachably coupled with both ends of the body and having the same diameter as the body; and a plurality of bolts closely fastening the body with the cover by extending through the cover and the body and coupling with the nuts and each made of different materials. The cross-sectional shapes of the density bars and bolts appear on the image scanned by the CT apparatus and the radiotherapy apparatus.

Projection images of a calibration phantom are picked up and stored. Three-dimensional position information on an X-ray tube and an area detector is obtained from the projection images and three-dimensional arrangement information on markers inside the calibration phantom. Three-dimensional position information is obtained for all projection images, and stored in a three-dimensional position information storage unit. Projection images of an object under examination are picked up by following the same tracks and the same sequence as when radiographing the calibration phantom. Radiographic data of the projection images is read. A reconstructing calculation is carried out for the object based on the three-dimensional position information on the X-ray tube and area detector relative to the calibration phantom, to create slice images or three-dimensional volume data of a selected site of the object.

A hybrid calibration method uses a calibration phantom (exterior reference) scanned simultaneously with the patient, and one or more known tissues of the subject (interior reference) to create a hybrid calibration reference that improves the measurement of tissue densities throughout the body. In addition, the calibration method is used to quantitatively define boundaries of tissue and organs for more accurate measurements of lengths, areas and volumes. Another aspect of the invention uses the calibrated images to quantitatively preset absolute window / levels for filming and image display, which provides standardized viewing for diagnostic purposes.

The present invention refers to 3D rotational X-ray imaging systems for use in computed tomography (CT) and, more particularly, to a fast, accurate and mathematically robust calibration method for determining the effective center of rotation (I) in not perfectly isocentric 3D rotational C-arm systems and eliminating substantially circular ring artifacts (RA) which arise when using such a CT scanner system for acquiring a set of 2D projection images of an object of interest to be three-dimensionally reconstructed. For this purpose, a C-arm based rotational CT scanner comprising at least one radiation detector (D) having an X-radiation sensitive surface exposed to an X-ray beam emitted by at least one X-ray tube (S), each rotating along a non-ideal circular trajectory (TF, TCD) about an object of interest to be three-dimensionally reconstructed from a set of 2D projection images is used for providing geometrical calibration data by scanning a calibration phantom from a plurality of distinct projection directions and calculating, for each projection direction, the 3D positions of the X-ray tube's focal spot and the X-ray detector's center. For approximating the exact 3D position and angular direction of the axis of rotation about which the at least one X-ray tube and the at least one radiation detector rotate, a circular regression technique using a number of mathematically robust least squares fits is applied.

The present invention relates to network enabled analysis of x-ray images. Also described are devices comprising calibration phantoms; methods of using these devices; methods of formulating databases containing information regarding x-ray images; the databases themselves; and methods of manipulating the information and databases.

Methods for empirical determination of a correction function for correcting beam hardening and stray beam effects of water-equivalent tissue in projection radiography or computed tomography using an imaging detector, and apparatuses for implementing the same are disclosed. The projection values obtained from the logarithmic values of the detector signals are corrected, the corrected projection values being represented by a correction function dependent on the tube voltage applied during the X-ray projection recording, the coefficients of which function are determined from a single calibration scan on an object-like calibration phantom made of water-like material.

A method for determining geometric imaging properties of a flat panel detector in an x-ray inspection system includes the steps arranging a calibration phantom between an x-ray source and the flat panel detector, wherein the calibration phantom comprises at least one discrete geometric object; recording at least one x-ray image of the calibration phantom with the flat panel detector, wherein at least one discrete geometric shape is generated in the x-ray image by imaging the at least one discrete geometric object of the calibration phantom; and determining a location-dependent distortion error of the flat panel detector from the at least one x-ray image on the basis of at least one characteristic of the at least one discrete geometric shape. All characteristics of the at least one discrete geometric shape used for determining the location-dependent distortion error are independent of the dimensions of the calibration phantom.

The present disclosure relates to the performing spectral calibration of a CT imaging system. In accordance with certain embodiments, spectral calibration phantoms are scanned while positioned on a table in the imaging volume of the CT imaging system. The scans of the calibration phantoms, in conjunction with air sans performed on the CT imaging system, are used to derive information about the deviation of the measured phantom scans from an ideal. The deviation information is in turn used to derive spectral calibration vectors that may be used with the CT imaging system.

An embodiment in accordance with the present invention provides a device and method for a quantitatively calibrated computed tomography scanner. The device includes a gentry configured for receiving a patient or part of a patient. The gentry includes an X-ray source and a detector positioned opposite said X-ray source, such that said detector receives the X-rays emitted from the X-ray source. Calibration phantoms are integrated with the gentry and / or a device within the scanner so as to allow for calibration in quantitative CT measurements of Hounsfield units and / or bone mineral density.

A method of calibration of a stereoscopic camera system (10,12) for use with a radio therapy treatment apparatus (14) is provided. Initially a calibration phantom (18) is positioned on an adjustable table (20) on the surface of a mechanical couch (16) with the phantom's centre at an estimated location for the iso-centre of a radio therapy treatment apparatus (14). The calibration phantom (18) is then irradiated using the radio therapy treatment apparatus (14) and the relative location of the centre of the calibration phantom and the iso-centre of the radio therapy treatment is determined by analysing images of the irradiation of the calibration phantom (18). The calibration phantom (18) is then repositioned by the mechanical couch (16) applying an offset corresponding to the determined relative location of the centre of the calibration phantom and the iso-centre of the radio therapy treatment apparatus (14) to the calibration phantom (18). The stereoscopic camera system (10,12) then proceeds to obtain images of the relocated calibration phantom (18) to which the offset has been applied and processes the obtained images to set the co-ordinate system of the stereoscopic camera system (10,12) relative to the iso-centre of the radio therapy treatment apparatus (14).

A method for geometric calibration of a CT scanner, including, for each row of at least one row of detector cells, establishing a complete geometric description of the CT scanner, including at least one unknown geometric parameter, establishing a description of a forward projection function using the complete geometric description, acquiring actual projection coordinates of a calibration phantom placed in a scanning field of view (SFOV) on a current row of detector cells and corresponding to a plurality of angles, acquiring calculated projection coordinates of the calibration phantom on the current row of detector cells and corresponding to the plurality of angles using the description of the forward projection function, and acquiring a calibrated value for the at least one unknown geometric parameter by evaluating the at least one unknown geometric parameter based on the acquired actual projection coordinates and calculated projection coordinates via a nonlinear least square fitting algorithm.

A multiple modality imaging system (10) includes a MR scanner (12) which defines an MR imaging region (18), a nuclear imaging scanner (26) which defines a nuclear imaging region (34), an CT scanner (36) which defines an CT imaging region (42). Each scanner (12, 26, 36) having a longitudinal axis along which a common patient support (46) moves linearly through the MR, nuclear, and CT imaging regions (18, 34, 42). A marker (130, 140, 150), for use with the system (10), includes a radio-isotope marker (132) which is imageable by the nuclear imaging scanner (26) and the CT scanner (36) surrounded by a flexible silicone MR marker (134) which is imageable by the MR scanner (12) and the CT scanner (36). A calibration phantom(162), for use with the image scanner (10), includes a plurality of the markers (130, 140, 150) supported by a common frame having a known and predictable geometry.

An apparatus, method, and computer program product for calibrating a CT scan without the use of an external calibration phantom, to enable quantitative assessment of internal body tissues and organs and additionally for any application that would benefit from a calibration of the scan attenuation data, such as viewing CT images in a consistent fashion. Embodiments are described with applications to quantitative assessment of bone density in the spine and hip, mineral content in blood vessels, hepatic-fat content in the liver, and gray-to-white matter ratio in the brain. The primary advantages of the method are that it does not require the use of an external calibration phantom, it is robust across different CT machines and scanner settings, and it is also highly precise, lending itself to a high degree of automation.

Disclosed herein is a magnetic resonance imaging calibration assembly in particular, for dynamic contrast—enhanced magnetic resonance imaging. An exemplary magnetic resonance imaging calibration assembly according to the present disclosure can comprise a subject receptacle for receiving at least a portion of a subject. The exemplary magnetic resonance imaging calibration assembly can further comprise a plurality of phantom compartments, each of which can contain a calibration phantom with a predetermined known T relaxation time. The plurality of phantom compartments can be attached to the subject receptacle in different ways. For example, according to some exemplary embodiments of the 10 present invention, the phantom compartments are separate compartments attached or fixed onto the subject receptacle. According to other exemplary embodiments, the phantom compartments can be formed at least partially by the subject receptacle. The phantom can be for a T1 calibration making use of its known T1.

For detecting the relative location of a laser or laser fan beam relative to the x-ray geometry of an x-ray device, a method for calibrating the position of the laser fan beam generated by a laser in relation to the projection geometry of the x-ray device is proposed. The x-ray device comprises an x-ray imaging system featuring an x-ray source and an x-ray detector. The x-ray source, the x-ray detector, the laser, and an imaging facility are arranged on a support. An optical x-ray calibration phantom is used for the calibration. The position of the imaging facility relative to the projection geometry is determined. The position of the laser fan beam relative to the imaging facility is determined. The position of the laser fan beam relative to the projection geometry is reconstructed.

This invention relates to a small pocket phantom designed to estimate the fundamental properties of imaging scanning acquisition including 3D resolution, noise, and scanner attenuation performance for different materials, together with an automated phantom analysis algorithm.

When calibrating a positron emission tomography (PET) scanner, a radioactive calibration phantom is scanned over a period of several half lives to acquire a plurality of frames of scan data. Interlaced timing windows are employed to facilitate acquiring coincidence data for a plurality of coincidence timing windows and energy windows during a single calibration scan. Coincident events are binned according to each of a plurality of selected coincidence windows, and the PET scanner is calibrated for each of the plurality of coincidence timing windows using data acquired from the single calibration scan.

A method is for calibration of a transformation of at least two X-ray attenuation values (which are determined using different X-ray spectra) for a material, to a value for the density and a value for the atomic number of the material. A first distribution is recorded of first X-ray attenuation values obtained from a calibration phantom using a first X-ray spectrum, and a second distribution is recorded of second X-ray attenuation values obtained from the calibration phantom using a second X-ray spectrum. The recorded X-ray attenuation values are used to produce a density function and to produce an atomic number function. A value for the density and for the atomic number of the calibration sample is determined with the aid of the density function and the atomic number function, and a discrepancy between the determined values and the actual density and atomic number of the calibration sample is found. The discrepancy is used for producing a mapping rule which changes the values determined by the density function and the atomic number function to the actual values.

A medical robot for use inside an MRI includes a horizontal motion assembly, a vertical motion assembly and a controller. The horizontal motion assembly and the vertical assembly each includes a motion joint, an ultrasonic motor operably connected to the motion joint and an encoder operably connected to the ultrasonic motor. The motor and encoder are positioned proximate to the joint of the respective horizontal motion assembly and vertical motion assembly. Each motor has a cross section positioned in one of the axial and sagittal plane of the MRI. A medical instrument assembly is operably connectable to one of the moving joint of the vertical motion assembly. The controller is operably connected to the horizontal motion joint and the vertical motion joint and it is adapted to be powered off when the magnetic resonance imager is being used to collect images.

A diagnostic imaging system comprises a plurality of radiation detectors (20) configured to detect radiation events emanating from an imaging region. The system comprises a calibration phantom (14) configured to be disposed in the imaging region spanning substantially an entire field of view and to generate radiation event pairs that define lines-of-response, wherein the calibration phantom is thin such that each LOR intersects the calibration phantom along its length, the thickness of the phantom being smaller than the length of the LORs. A calibration processor (24) receives input of the radiation detectors and calculates an incidence angle independent crystal delay tau i for each detector. The calibration processor (24) constructs a first look-up table for the timing correction of each LOR and a second look-up table for the angle depth of interaction correction for each crystal by combining tau i and eta i.