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  Ion beam delivery equipment and an ion beam delivery methodUSPTO Application #: 20060163496Title: Ion beam delivery equipment and an ion beam delivery method Abstract: The invention is intended to increase the number of patients treatable using one wheel having a thickness varied in the rotating direction to change energy of an ion beam passing the wheel. Ion beam delivery equipment for irradiating an ion beam to a patient for treatment comprises a beam generator for producing and accelerating the ion beam, an beam delivery nozzle including a range modulation wheel which has a predetermined thickness distribution in the rotating direction and is rotated on a travel passage of the ion beam generated from the beam generator to control a range of the ion beam, and an irradiation controller for controlling the beam producing and accelerating operation of the beam generator in accordance with the phase of rotation of the range modulation wheel. (end of abstract) Agent: Dickstein Shapiro Morin & Oshinsky LLP - Washington, DC, US Inventors: Kazuo Hiramoto, Hiroshi Akiyama, Masaki Yanagisawa, Hisataka Fujimaki, Alfred Smith, Wayne Newhauser USPTO Applicaton #: 20060163496 - Class: 250492300 (USPTO) Related Patent Categories: Radiant Energy, Irradiation Of Objects Or Material, Ion Or Electron Beam Irradiation The Patent Description & Claims data below is from USPTO Patent Application 20060163496. Brief Patent Description - Full Patent Description - Patent Application Claims
BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to ion beam delivery equipment and ion beam delivery method, which are used to produce and deliver ion beam, e.g., proton or carbon ions, to a tumor for treatment. [0003] 2. Description of the Related Art [0004] There is known a method for delivering ion beam, e.g., proton or carbon ions, to a tumor, such as a cancer, in the body of a patient. The ion beam delivery equipment for such treatment comprises an ion beam generator to produce the said ion beam and accelerate it to a needed energy, a beam transport system, and an beam delivery nozzle. An ion beam accelerated by the beam generator reaches the beam delivery nozzle, which is installed in a rotating gantry to monitor and shape the therapeutic radiation field, through a first beam transport system and a second ion beam transport system, the latter being installed in the rotating gantry. The ion beam reached the beam delivery nozzle is delivered to the tumor in the patient body from the beam delivery nozzle. Known examples of the beam generator include a synchrotron (quasi-circular accelerator) provided with an extraction deflector for extracting the ion beam from the orbit (see, e.g., Patent Reference 1; U.S. Pat. No. 5,363,008). [0005] In radiation therapy using an ion beam, e.g., with a proton beam delivering a radiation dosage to a tumor, by utilizing characteristics that most of the energy of the proton beam is released just before protons come to rest, namely that a Bragg peak is formed just before the stop of protons, the energy of the proton beam is selected to stop protons in the tumor so that the beam energy is released most to cells within the tumor or its microscopic extensions. [0006] Usually, the tumor has a certain thickness in the direction of depth, i.e. along the direction of the ion beam, from the body surface of a patient (hereinafter referred to simply as "the direction of depth"). To effectively irradiate the ion beam over the entire thickness of the tumor in the direction of depth, the width of the Bragg peak must be spread out in the direction of depth. The spread-out width of the Bragg peak is called a Bragg peak width. To obtain the required Bragg peak width, the energy of the ion beam must be modulated. [0007] From that point of view, a range modulation wheel (RMW) has already been proposed in which a plurality of blades each having a thickness varied step by step in the circumferential direction are installed around a rotating shaft (see, e.g., Non-patent Reference 1; "REVIEW OF SCIENTIFIC INSTRUMENTS", Vol. 64, No. 8, pp 2074-2084 (FIGS. 30 and 31) issued in August, 1993). The plural blades are mounted to the rotating shaft. In the RMW, a through opening is formed between adjacent sets of the blades. For example, when the RMW is rotated from a state in which the opening is positioned on a path of the ion beam (hereinafter referred to simply as a "beam path"), the opening and the blade alternately intersect the beam path. At the time when the ion beam passes through the opening, the energy of the ion beam is not attenuated and therefore the Bragg peak is produced in the deepest position inside the patient body. At the time when the ion beam passes through a blade, the energy of the ion beam is attenuated more as the ion beam passes through the blade having a larger thickness, and therefore the Bragg peak is produced in a portion of the tumor near the body surface of the patient. With the rotation of the RMW, the position in the direction of depth where the Bragg peak is formed varies cyclically. As a result, the Bragg peak width being comparatively wide and flat in the direction of depth of the tumor can be obtained, looking at the beam energy integrated over time. SUMMARY OF THE INVENTION [0008] The known method described above has the problem as follows. [0009] Patients have body dimensions different from one another and tumor sizes also differ from one another. Accordingly, the Bragg peak width optimum for treatment of the tumor differs for each of the patients. With the known method, however, only one set Bragg peak width is obtained from one RMW. This has invited the necessity of forming and preparing a different RMW for each patient and replacing the RMW whenever the patient is changed, and hence has caused a difficulty in efficiently treating a large number of patients. [0010] It is an objective of the present invention to provide an ion beam delivery equipment and an ion beam delivery method, which can increase the number of patients treatable using one wheel having a thickness varied in the rotating direction to change energy of the ion beam passing the wheel. [0011] To achieve the above objective, the present invention is featured in that start and stop of extraction of the ion beam accelerated in the beam generator is controlled during rotation of a wheel having a thickness varied in the rotating direction to change energy of the ion beam passing the wheel. By controlling the start and stop of extraction of the ion beam from the beam generator during the rotation of the wheel, a region of the wheel where the ion beam passes the wheel can be changed in the rotating direction. It is therefore possible to form a plurality of spread-out beam peak (Bragg peak) widths (hereinafter referred to as "SOBP widths") having different values in the direction of depth from the body surface of a patient by using one modulation wheel, and to employ one wheel for a plurality of patients. In other words, various patients having tumors with different thickness can be treated with one modulation wheel. [0012] Preferably, a synchrotron is used as the beam generator. [0013] Preferably, the wheel is provided with a plurality of blades each having a thickness varied in the rotating direction. [0014] Preferably, the control of the start and stop of extraction of the ion beam from the beam generator is done by using the information for the SOBP width sent from the treatment planning software through communication network. [0015] According to the present invention, since the modulation wheel has the thickness varied in the rotating direction to change energy of the ion beam passing the wheel, the number of patients treatable using one modulation wheel can be increased. BRIEF DESCRIPTION OF THE DRAWINGS [0016] FIG. 1 is an overall block diagram of ion beam delivery equipment according to a first embodiment, i.e., one preferable embodiment, of the present invention; [0017] FIG. 2 is a vertical sectional view showing an internal structure of an beam delivery nozzle shown in FIG. 1; [0018] FIG. 3 is a perspective view of an RMW shown in FIGS. 1 and 2; [0019] FIG. 4 is a plan view of the RMW shown in FIG. 3, the view showing, by way of example, ion beam emission cases a to c; [0020] FIG. 5 is a chart showing beam-on and beam-off periods in each of the cases a to c, shown in FIG. 4, on the time serial base; [0021] FIG. 6 is a graph showing a dose distribution and a SOBP (spread-out beam peak) width in the direction of depth in each of the cases a to c shown in FIG. 4; Continue reading... Full patent description for Ion beam delivery equipment and an ion beam delivery method Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Ion beam delivery equipment and an ion beam delivery method patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. Start now! - Receive info on patent apps like Ion beam delivery equipment and an ion beam delivery method or other areas of interest. ### Previous Patent Application: Apparatus and method for irradiating electron beam Next Patent Application: Ion beam therapy system and its couch positioning method Industry Class: Radiant energy ### FreshPatents.com Support Thank you for viewing the Ion beam delivery equipment and an ion beam delivery method patent info. 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