RU2702316C1 - Method for verification of patient's laying in remote beam therapy and dual-energy detector device circuit - Google Patents

Abstract

FIELD: medicine.

SUBSTANCE: group of inventions relates to radiation monitoring methods, namely to an X-ray method, and can be used in verification of the patient's position relative to the isocenter of the remote beam therapy apparatus. Method for verification of patient's laying in remote beam therapy consists in placing patient so that patient's controlled area of patient is located in initial position relative to X-ray radiation flux of remote radiation therapy apparatus, dividing radiation transmitted through patient's body area into low-energy and high-energy components of X-ray spectrum by means of filter, detecting transmitted radiation on a flat panel x-ray detector and processing data from the detector after completion of exposure, wherein filter is fixed on end of flat panel detector of X-ray radiation, absorbs low-energy component of X-ray spectrum and covers half of pixels of detector in staggered order or by means of parallel lamels, half of pixels of detector registers radiation, not interacting with filter, and forms first group of pixels, and other half of pixels of detector registers radiation passed through filter, and forms second group of pixels, wherein radiation detection condition is provided when combination of four adjacent pixels consists of two pixels of first group, detecting radiation, not interacting with filter and representing full spectrum of X-ray radiation, and two pixels of the second group, detecting radiation passing through the filter and representing high-energy component of the X-ray radiation spectrum, when processing data in each of the pixel groups, adding the signals, subtracting the signal of the second group of pixels from the first and obtaining information on the low-energy component of the X-ray spectrum obtained for the four pixels of the first and second groups, which is referred to the average pixel coordinate, then boundaries of patient's controlled area are determined and combined with data from remote beam therapy planning system. A device for implementing the method comprises an apparatus for remote radiation therapy, a filter configured to divide radiation transmitted through the patient's body region into low-energy and high-energy components of the X-ray spectrum, and a flat panel x-ray detector.

EFFECT: using the group of inventions makes it possible to improve the quality of obtained 2D images, including in cases when the analyzed area of the patient is in process of movement related to respiration or other physiological processes of the organism.

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Description

The invention relates to radiation control methods, in particular to an X-ray method, and can be used to verify the position of the patient relative to the isocenter of the apparatus for remote radiation therapy.

A known method of verification using a spiral computed tomography scanner, located in the same room as the radiation therapy apparatus, the table provides the positioning of the patient in the therapeutic and diagnostic apparatus by obtaining a 3-dimensional tomogram [1].

Also known is a method of controlling the patient’s styling using a magnetic resonance imager, which can be located both in a separate room and in combination with a radiation therapy apparatus [2], [3].

Known methods and methods for verification of patient placement and the use of megavolt (MB) imaging systems based on obtaining shadow projections of the patient's studied area with a therapeutic beam and registering this beam with a flat panel detector located after the patient, both with and without markers inserted into the patient. In this case, the combination of initial data from the planning system occurs both according to planar data and tomographic [4], [5].

The closest in technology and design is a method of verification of patient placement during remote radiation therapy, which implements obtaining kV images using an X-ray tube with operating voltages in the range of 80 - 140 kV and registering radiation transmitted through the patient’s body with a flat panel detector. In this case, verification can be carried out both using radiopaque markers inserted into the near-tumor space, and by combining bone structures or soft tissues of the patient’s body [6], [7].

The disadvantage of these verification methods is the low accuracy of positioning, due to the low contrast of the image, which in turn is a consequence of the limited dynamic range of the applied visualization systems.

The technical result of the present invention is to improve the quality of the obtained 2D images, including in cases where the patient’s studied area is in the process of movement associated with breathing or other physiological processes of the body. Improving the quality of images consists in more clearly defining the boundaries of the target for further alignment with data from the planning system. This provides a more correct verification of the patient's styling during remote radiation therapy.

The indicated technical result is achieved by separating the low-energy and high-energy components of the X-ray spectrum absorbed in the detector, due to the fact that the profile of the filtering system of transmitted radiation creates such a radiation flux that some of the pixels of the detector register radiation that has not interacted with the filter, and the other half of the pixels register radiation passing through the filter. In this case, the condition must be ensured that the combination of four adjacent pixels consists of two pixels recording radiation that did not interact with the filter and two pixels recording radiation passing through the filter.

To implement the method, a diagram of the device is shown (Figs. 1 and 2), comprising: an x-ray apparatus 1, which generates a directed x-ray flux 2 of the studied region of the patient’s body 3, through which a directed x-ray flux passes, a flat-panel x-ray detector 5 with a fixed on its end a filter 4 located at the minimum possible distance to the scintillator and overlapping half the detector pixels in a checkerboard pattern (Fig. 2a) or in the form of parallel lamellas (Fig. 2b).

The device operates as follows: the device is installed in a room with an apparatus for remote radiation therapy and is placed directly on or next to the radiation therapy apparatus. In this case, you need to know information about the relative positions of the centers of the apparatus and device. The controlled area of the patient’s body 3 is located in the initial position, after which the x-ray apparatus 1 creates a stream of x-ray radiation directed to the controlled area of the patient’s body. The radiation transmitted through the patient enters the X-ray filter 4. Part of the radiation, namely, the low-energy component of the spectrum, is absorbed in the filter. In the future, the X-ray detector detects the entire field of x-ray radiation, both transmitted and not passed through the filter 5.

After exposure is complete, the data from the detector is processed. The essence of data processing is as follows: data are taken from four neighboring pixels, two of which register radiation that did not interact with the filter, i.e. the full spectrum of radiation (group 1), and two other pixels register radiation after interacting with the filter, i.e. high-energy part of the radiation spectrum (group 2). Next, the signals are added in each of the groups of pixels and the signal of the second group of pixels is subtracted from the first, which gives information about the low-energy component of the spectrum. Information on the low-energy component of the spectrum obtained in a group of four pixels is assigned to the average coordinate of these pixels.

Literature

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[2] Robba Rai, MHlthSc, Shivani Kumar, MPH, Vikneswary Batumalai, PhD, Doaa Elwadia, BAppSc, Lucy Ohanessian, BAppSc, Ewa Juresic, MMagResonTech, Lynette Cassapi, BSc, Shalini K. Vinod, MD, Lois Holis Paul J. Keall, PhD, & Gary P. Liney, PhD "The integration of MRI in radiation therapy: collaboration of radiographers and radiation therapists". Collaboration of radiographers and radiation therapists. Journal of Medical Radiation Sciences, February 2017, 64 61-68. DOI: 10.1002 / jmrs.225

[3] Benjamin W. Fischer-Valuck MD, Lauren Henke MD, "Two-and-a-half-year clinical experience with the world's first magnetic resonance image guided radiation therapy system". Adv Radiat Oncol. 2017 Jun l; 2 (3): 485-493. DOI: 10.1016 / j.adro.2017.05.05.006. eCollection 2017 Jul-Sep.

[4] Nithya Kanakavelua, E. James Jebaseelan Samueld "Assessment and evaluation of MV image guidance system performance in radiotherapy". Rep Pract Oncol Radiother. 2015 May-Jun; 20 (3): 188-97. doi: 10.1016 / j.rpor.2015.01.002. Epub 2015 Feb 7.

[5] Olivier Morin B.S.E., Amy Gillis M.D., Josephine Chen Ph.D., Michele Aubin M.S.E.E., M. Kara Bucci M.D., Mack Roach III M.D., Jean Pouliot Ph.D. "Megavoltage cone-beam CT: System description and clinical applications." Med Dosim. 2006 Spring; 31 (1): 51-61. DOI: 10.1016 / j.meddos. 2005.12.009.

[6] Peter H. Goff MD, PhD, Louis B. Harrison MD, FASTRO, Eli Furhang PhD, Evan Ng MBBS, FRANZCR, Stephen Bhatia RTT, Frieda Trichter DSc, Ronald D. Ennis MD "2D kV orthogonal imaging with fiducial markers is more precise for daily image guided alignments than soft-tissue cone beam computed tomography for prostate radiation therapy ". Adv Radiat Oncol. 2017 May 4; 2 (3): 420-428. DOI: 10.1016 / j.adro. 2017.05.001. eCollection 2017 Jul-Sep.

, Stine Korreman, Peter Meidahl Petersen "Comparison of the accuracy and precision of prostate localization with 2D-2D and 3D images". Radiother Oncol. 2011 Feb;98(2).175-80. doi: 10.1016/j.radonc.2010.11.012. Epub 2010 Dec 21.[7]

, Stine Korreman, Peter Meidahl Petersen "Comparison of the accuracy and precision of prostate localization with 2D-2D and 3D images." Radiother Oncol. 2011 Feb; 98 (2). 175-80. doi: 10.1016 / j.radonc. 2010.11.012. Epub 2010 Dec 21.

Claims (2)

1. A method for verifying the patient’s styling during remote radiation therapy, which consists in laying the patient so that the controlled portion of the patient’s body is in the initial position relative to the x-ray flux of the remote radiation therapy apparatus, dividing the radiation transmitted through the patient’s body into low-energy and high-energy components of the x-ray spectrum through a filter, registration of transmitted radiation on a flat-panel x-ray detector from radiation and processing the data from the detector after completion of exposure, characterized in that the filter is mounted on the end of the flat-panel X-ray detector, absorbs the low-energy component of the X-ray spectrum and overlaps half of the detector pixels in a checkerboard pattern or by means of parallel lamellas, half of the detector pixels detects radiation that did not interact with filter, and forms the first group of pixels, and the other half of the detector pixels registers the radiation that passed cut filter, and forms a second group of pixels, while the condition for registering radiation is provided when a combination of four adjacent pixels consists of two pixels of the first group, recording radiation that does not interact with the filter and representing the full spectrum of x-ray radiation, and two pixels of the second group, recording radiation passing through the filter and representing the high-energy component of the x-ray spectrum, when processing data in each of the groups of pixels, the addition of signals, subtract the signal of the second group of pixels from the first and obtain information about the low-energy component of the X-ray spectrum obtained for the four pixels of the first and second groups, which is related to the average coordinate of the pixels, after which the boundaries of the controlled area of the patient’s body are determined and combined with data from the system planning remote radiation therapy. 2. A device for implementing the method according to claim 1, comprising an apparatus for remote radiation therapy, a filter configured to separate radiation transmitted through the patient’s body area into low-energy and high-energy components of the X-ray spectrum, and a flat-panel x-ray detector, characterized in that the filter is fixed at the end of a flat-panel x-ray detector, is configured to absorb the low-energy component of the x-ray spectrum and cross over the half of the pixels of the x-ray detector in a checkerboard pattern or by means of parallel lamellas, while the detector is installed so that half of its pixels detects radiation that has not interacted with the filter, and forms the first group of pixels, and the other half of the pixels of the detector detects radiation transmitted through the filter , and forms a second group of pixels, and is designed in such a way that a condition for registering radiation is provided when the combination of four adjacent pixels consists of two the pixels of the first group, recording radiation that does not interact with the filter and representing the full spectrum of x-ray radiation, and the two pixels of the second group, recording radiation that passed through the filter and representing the high-energy component of the x-ray spectrum.

Images