Surgery: light – thermal – and electrical application – Light – thermal – and electrical application – Electrical therapeutic systems
Reexamination Certificate
2001-11-15
2004-06-01
Manuel, George (Department: 3762)
Surgery: light, thermal, and electrical application
Light, thermal, and electrical application
Electrical therapeutic systems
Reexamination Certificate
active
06745072
ABSTRACT:
The present invention relates to a method of checking the beam generation means and beam acceleration means of an ion beam therapy system that is operated especially with heavy ions.
Ion beam therapy systems are preferably used in the treatment of tumours. An advantage of such systems is that, on irradiation of a target object (target), the major portion of the energy of the ion beam is transferred to the target, while only a small amount of energy is transferred to healthy tissue. A relatively high dose of radiation can therefore be used to treat a patient. X-rays, on the other hand, transfer their energy equally to the target and to healthy tissue, so that for health reasons, for the protection of the patient, it is not possible to use high doses of radiation.
There is known from U.S. Pat. No, 4,870,287, for example, an ion beam therapy system in which there are generated from a proton source proton beams of which the protons can be delivered to various treatment or irradiation sites by an acceleration device. Provided at each treatment site is a rotating cradle having a patient couch so that the patient can be irradiated with the proton beam at different angles of irradiation. While the patient is spatially located in a fixed position inside the rotating cradle, the rotating cradle revolves round the body of the patient in order to focus the treatment beams at various angles of irradiation onto the target located in the isocentre of the rotating cradle. The acceleration device comprises a combination of a linear accelerator (LINAC) and a so-called synchrotron ring.
In H.F. Weehuizen et al. CLOSED LOOP CONTROL OF A CYCLOTRON BEAM FOR PROTON THERAPY, KEK Proceedings 97-17, January 1998, a method of stabilising the proton beam in proton beam therapy systems is proposed in which the treatment beam is actively so controlled that it is located on the centre line of the corresponding beam delivery system at two measurement points spaced from each other in the longitudinal direction. The first measurement point is located between a pair of deflection magnets and is formed by a multi-wire ionisation chamber. Depending on the actual value of the beam position delivered from that multi-wire ionisation chamber relative to the centre point of the beam path, a PI control is generated by further deflection magnets arranged upstream from the first-mentioned pair of deflection magnets. The second measurement point is located just upstream of the isocentre and is formed by an ionisation chamber which is divided into four quadrants. Depending on the actual position value of that ionisation chamber, again PI control signals are generated, but those control signals are intended for the first-mentioned deflection magnets. Such a control arrangement is said to render possible both angle stability in terms of the centre line of the beam delivery system and lateral position stability of the proton beam.
When, however, heavy ion irradiation is carried out, that is to say irradiation with ions that are heavier than protons, large and heavy devices are necessary, with the result that there is a tendency to avoid the use of rotating cradles and instead move the patient or the patient couch. Corresponding therapy systems are described, for example, in E. Pedroni: Beam Delivery, Proc. 1
st
Int. Symposium on Hadrontherapy, Como, Italy, Oct. 18-21, 1993, page 434. Such systems are accordingly eccentric systems.
Since, however, mainly isocentric systems are preferred by oncologists, a heavy ion beam therapy system was proposed in which, although rotating cradles are used at the treatment sites, the radii of the rotating cradles can be reduced by virtue of the treatment beam delivered to each rotating cradle horizontally along its axis of rotation being so guided by means of suitable magnet and optics arrangements that, for the irradiation of a target, the beam is first of all directed away from the axis of rotation and later crosses the axis of rotation again in the isocentre. There is provided for the irradiation of the target a grid scanner, which comprises vertical deflection means and horizontal deflection means, each of which deflects the treatment beams at right angles to the beam axis, with the result that an area surrounding the target is scanned by the treatment beams. Such a system thus essentially provides beam guidance in only one plane of the rotating cradle.
The irradiation by the grid scanner is carried out with the aid of radiation dose data that are calculated automatically by the supervisory control system of the ion beam therapy system according to the patient to be irradiated or treated.
Since a high level of operational safety and operational stability in terms of the treatment beam is necessary in ion beam therapy systems, a monitoring device for monitoring the treatment beam delivered by the grid scanner is provided in the afore-described heavy ion beam therapy system. The monitoring device is arranged between the last deflection magnets of the above-mentioned magnet arrangement and the isocentre, and can comprise ionisation chambers for monitoring the particle flow and multi-wire chambers for monitoring the beam position and the beam width.
For safety reasons, various DIN standards have to be observed in the operation of medical electron accelerators. Those standards are concerned on the one hand with the inspection test, that is, the inspection of the readiness for operation, and on the other hand with the consistency test, that is, examination of operational stability, of the system. For ion beam therapy systems, especially for heavy ion beam therapy systems, safety standards of that kind developed specifically for such systems are not yet known, but there is still a need, in ion beam therapy systems too, for as high as possible a level of operational safety and operational stability.
The problem underlying the present invention is therefore to propose a method of checking the beam generation means and the beam acceleration means of an ion beam therapy system in order to improve operational safety and operational stability, especially in respect of the beam generation means and the beam acceleration means. The process shall at the same time be suitable especially for use with heavy ions.
The problem is solved in accordance with the present invention by a method having the features of Claim 1. The dependent claims each define preferred and advantageous embodiments of the present invention.
According to the present invention, an ion beam therapy system that has at least one ion source, one acceleration device and one beam guidance system is operated, wherein the type of ion, the ion beam energy, the ion beam intensity and the blocking of the accelerator and also the means for terminating extraction are checked. For that purpose, the type of ion is checked by recording the charge spectrum of the ion source in a high-charge injector and comparing it with a reference spectrum. The ion beam energy is checked by measuring Bragg curves in selected energy levels in an absorber ionisation chamber system. The ion beam intensity is checked by measuring the particle intensity in the accelerator device in an upper range of intensity, and measuring the particle intensity at the irradiation site for all planned levels of intensity. The blocking of the accelerator is checked by sending switch-off commands and adjustment commands to components that are deactivated beforehand.
The means for terminating extraction are checked by generating an interlock condition during an ion extraction and measuring decay time of the ion extraction.
In the present invention there are used especially
12
C
2+
ions, which are stripped to
12
C
6+
in the beam guide between a linear accelerator and a synchrotron ring. For that purpose, a stripper is provided downstream of the linear accelerator. Owing to their physical and biological properties, those carbon ions have proved to be very effective in the treatment of tumours and have the advantages of a high physical selectivity and a high biological effectiv
Badura Eugen
Eickhoff Hartmut
Haberer Thomas
Poppensieker Klaus
Schardt Dieter
Frommer & Lawrence & Haug LLP
Gesellschaft fuer Schwerionenforschung mbH
Manuel George
Santucci Ronald R.
LandOfFree
Method for checking beam generation and beam acceleration... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method for checking beam generation and beam acceleration..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method for checking beam generation and beam acceleration... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3311330