Pages 4359-4367. Citing Literature. MeSH terms Animals Equipment Design Models, Animal Monte Carlo Method Phantoms, Imaging Radiotherapy / methods An apparatus and method for coupling a fixed-aperture collimator to a variable-aperture collimator. An apparatus and method for coupling a fixed-aperture collimator to a variable-aperture collimator. In a light-localizing, variable-aperture collimator: a. Variable aperture z-axis tracking collimator for computed tomograph system . Collimator Studies. The U.S. Department of Energy's Office of Scientific and Technical Information Added filtration is required b. The simplicity of this design comes from the VAC having a small apertureabout 4 5 cmand thus needing only eight moving SBAs . A thin section of glass is used. This variable aperture collimator technology is therefore a feasible and flexible solution for adjustable shaping of radiation beams for use in small animal radiotherapy as well as other applications in which beam shaping is desired. e.) Windows made of copper are used. This idea has led to the variable-aperture collimator (VAC) in which pairs of single bixel attenuators (SBAs) can be moved to any conguration in each of the collimator rows (Webb 2002b, 2004, Webb et al 2003). The pre-patient collimator includes a plurality of eccentric cams and a filtration device for altering the x-ray beam radiated from a x-ray source. The blocks may be offset at the apex angle to provide a non-equilateral aperture. A second model of a completely adjustable, variable aperture neutron collimator has been developed. Adjustable-focal-length collimators method and system US7671340; Embodiments relate to an imaging system that includes a collimator assembly having one or more pinhole apertures therein. 6298117 - 693367& - USPTO Application Oct 20, 2000 - Publication Oct 02, 2001 . Variable aperture z-axis tracking collimator for computed tomograph system: 2001-01-09: Hample et al. . They together produce a 12-sided aperture with an accuracy 0.2 mm at nominal distance of 800 mm [1]. This paper extends some earlier concepts of using a tertiary mask plus jaws for delivering IMRT without a multileaf collimator. The variable-aperture collimator may be an IRIS collimator having multiple leaves configured to open and close an aperture of the IRIS collimator within which the fixed-aperture collimator is retained. The variable-aperture collimator may be an IRIS collimator having multiple leaves configured to open and close an aperture of the IRIS collimator within which the fixed-aperture collimator is retained. A plurality of beam opaque blocks are in sliding interface edge contact to form a variable aperture. Shutters. collimator z-location. back in January we were discussing the collimator design and the backgrounds Roger suggested trying to make the lower edge of the collimator defined a.) An apparatus and method for coupling a fixed-aperture collimator to a variable-aperture collimator. Volume 34, Issue 11. R20 VARIABLE APERTURE COLLIMATOR MECHANICAL CONSTRUCTION AND MANUAL CONTROL. Are mounted as close as possible to the tube window to reduce the amount of off-focus radiation (x-rays emitted from parts of the tube other than the focal spot) coming from the primary beam & exiting at various angles from the x-ray tube window, upper part. Positive beam limiting device. 0.5 mm Al c.) 1.0 mm Al d.) 2.0 mm Al e.) 2.5 mm Al. 3) can be minimized by increasing the width of the base of each block. The Iris collimator contains two stacked hexagonal banks of tungsten segments that together produce a 12-sided aperture that can be continuously varied [1]. Our design feature includes a variable-aperture full-ring geometry to overcome the limited field of view and independently swiveling detectors . The most modern and commonly used beam-restricting device in radiography. The eccentric cams are positioned to collimate the x-ray beam and may be . Volume 34, Issue 11. The variable-aperture collimator may be an IRIS collimator having multiple leaves configured to open and close an aperture of the IRIS collimator within which the fixed-aperture collimator is retained. The potential of the variable-aperture collimator (VAC) in intensity-modulated radiation therapy (IMRT) has been evaluated by comparing its performance with that of the multi-leaf collimator (MLC). Related; Equipped with a PBL device, light field illumination is unnecessary c. If the lightbulb burns out, the graduated scale on the adjusting mechanism can be used d. It is not necessary to center the crosshairs in the light beam e. Misalignment between the collimator assembly and the x-ray source could be identified on the transmission images and corrected by adjustment of the collimator location. This comparison used a decomposition algorithm to find the series of collimator segments that would treat a given intensity-modulated beam (IMB . The blocks may be offset at the apex angle to provide a non-equilateral aperture. Variable Aperture. This variable aperture collimator technology is therefore a feasible and flexible solution for adjustable shaping of radiation beams for use in small animal radiotherapy as well as other applications in which beam shaping is desired. The eccentric cams are positioned to . The pre-patient collimator includes a plurality of eccentric cams and a filtration device for altering the x-ray beam radiated from a x-ray source. z location revisited new field map preliminary tilt studies some target boiling results. The U.S. Department of Energy's Office of Scientific and Technical Information In orde. Wedge filters are: Pages 4359-4367. The new concept is to sweep a variable-aperture collimator (VAC) across the space of the intensity-modulated beam (IMB) to be delivered and to strip this IMB down into multiple-static-field components, each deliverable with the VAC. The collimator should be removed. Variable aperture z-axis tracking collimator for a computed tomograph system. A variable aperture beam collimator as described in claim 9 and including means for translating the guide members of each block assembly said means for translating comprising a pinion member operably connected to each block assembly and a worm gear mounted between said pinions for simultaneously translating the guide members of each block assemb. The variable-aperture collimator may be an IRIS collimator having multiple leaves configured to open and close an aperture of the IRIS collimator within which the fixed-aperture collimator is. The use in the CyberKnife The equivalent added filtration provided by a conventional light-localizing, variable-aperture collimator is closest to: a.) This variable aperture collimator technology is therefore a feasible and flexible solution for adjustable shaping of radiation beams for use in small animal radiotherapy as well . PBL, Automatic collimator, Detects film size and automatically adjusts. One method of constructing a variable aperture col- limator for use in conjunction with an operating table could use sets of blocks mounted in a horizontal plane under the table. The CyberKnife (CK) system (Accuray Inc., Sunnyvale, CA) can be equipped with an optional Iris Variable Aperture Collimator (Iris) containing two stacked hexagonal banks of tungsten segments. Abstract An apparatus is disclosed providing a variable aperture energy beam collimator. Collimator. The variable-aperture collimator may be an IRIS collimator having multiple leaves configured to open and close an aperture of the IRIS collimator within which the fixed-aperture collimator is. Full Record; Other Related Research; Authors: Repeta, L E; Curtiss, J A Publication Date: Thu Jan 01 00:00:00 EST 1970 378/4: 6056437: Methods and apparatus for imaging system detector alignment: 2000-05-02: Toth: 378/205: 5982846 Abstract: . This redesigned model can be scaled to a full-size device appropriate for use in a medical facility. They together produce a 12-sided aperture with an accuracy 0.2 mm at nominal distance of 800 mm [1]. Lack of shielding at the four corners of each collimator section (as shown in fig. 378/150: 6061419: Methods and apparatus for noise compensation in an imaging system: 2000-05-09: Hsieh et al. Treatment of small animals with radiation has in general been limited to planar fields shaped with lead blocks, complicating spatial localization of dose and treatment of deep-seated targets. The U.S. Department of Energy's Office of Scientific and Technical Information A plurality of collimator block assemblies may be employed for providing a channel defining a collimated beam. Light-Localizing variable-Aperture rectangular collimator. Two sets made of lead and laid horizontally inside the device. The imaging system is configured so that one or more of the pinhole apertures has an adjustable focal length.The imaging system further includes a detector assembly configured to generate one or more signals . November 2007. optimized collimator design, we further evaluated a full-ring SPECT system design with eight large-area CZT detectors that can be used for a broad spectrum of single-photon emitting radiopharmaceuticals. The Iris aperture A variable irradiation range adjusting device of a digital tomographic image synthesizing system comprises a trapezoidal irradiation range adjusting device configured to take a trapezoidal shape having a longer length than a side of a direction in which an X- The trapezoidal irradiation range adjusting device is configured to adjust the shape of the irradiated X-ray to the size of the detector . 0 mm Al b.) The variable-aperture collimator may be an IRIS collimator having multiple leaves configured to open and close an aperture of the IRIS collimator within which the fixed-aperture collimator is retained. A plurality of beam opaque blocks are in sliding interface edge contact to form a variable aperture. Are adjustable for an infinite number of field sizes. An apparatus is disclosed providing a variable aperture energy beam collimator. This variable aperture collimator technology is therefore a feasible and flexible solution for adjustable shaping of radiation beams for use in small animal radiotherapy as well as other applications in which beam shaping is desired. Inventors: United States Patent 6173039 . The CyberKnife (CK) system (Accuray Inc., Sunnyvale, CA) can be equipped with an optional Iris Variable Aperture Collimator (Iris) containing two stacked hexagonal banks of tungsten segments. An apparatus and method for coupling a fixed-aperture collimator to a variable-aperture collimator. November 2007.

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