X-ray or gamma ray systems or devices – Specific application – Absorption
Patent
1995-04-14
1997-05-06
Porta, David P.
X-ray or gamma ray systems or devices
Specific application
Absorption
378 68, A61N 510
Patent
active
056278705
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a device for treating cerebral lesions by gamma radiation, of the type comprising an approximately hemispherical source/collimator assembly which includes a large number of gamma-ray sources associated with channels which are all oriented towards one and the same focusing point.
BACKGROUND OF THE INVENTION
Gamma-radiation apparatuses have been proposed for non-invasive neurosurgery of the brain in order to treat cerebral lesions without opening the cranium. Destruction of the lesions is achieved by precisely concentrating gamma radiation onto the areas to be treated, such as venous malformations or tumors. These apparatuses are often designated by the name "gamma surgical apparatuses" or "gamma bistouries".
In these apparatuses, external gamma-radiation sources are used, the radiation being directed and concentrated, in a precise manner, onto the treated lesion in order for the desired dose to be absorbed by this lesion without appreciably damaging the intermediate tissues intervening between the sources and the lesion, nor the tissues surrounding the lesion and, in a general manner, reducing to a minimum the radiation doses absorbed by the healthy tissues.
This is achieved especially by the devices of the aforementioned type, an example of which is described in FR-A-2,672,220. In this technology, a large number of fixed external sources are used, these being collimated individually and arranged radially so that the axes of the rays that they produce converge onto a focal point which coincides with the lesion to be treated. The intensity of each beam is insufficient to damage the intermediate healthy tissues through which it passes, especially as the device is given, during the treatment, an angular movement about the focusing point. In contrast, at the point of convergence or focal point, the dose received by the lesion is sufficient to destroy it.
In this known technique, each source is associated with an at least approximately conical single channel, the generatrices of which converge towards the focusing point and in which a conical central needle made of a material absorbing the gamma rays is positioned.
SUMMARY OF THE INVENTION
The object of the invention is to improve this known device so as better to concentrate the radiation at the focusing point in order to improve the effectiveness of the treatment, while at the same time better protecting the healthy areas in the brain from the gamma radiation.
For this purpose, the invention is a treatment device of the aforementioned type, in which each gamma-ray source is associated with a bundle of channels bounded by a conical envelope of revolution, the vertex of which is located at the focusing point.
The device may include one or more of the following characteristics: bundle which is associated with it;
The invention also relates to an apparatus for treating cerebral lesions by gamma radiation, comprising a device such as defined hereinabove, and a movable patient-supporting table equipped with a stereotactic device intended to interact with the patient's head.
BRIEF DESCRIPTION OF THE DRAWINGS
An illustrative embodiment of the invention will now be described with reference to the appended drawings, in which:
FIG. 1 is a schematic overall view, in side elevation and partly in section, of a treatment apparatus in accordance with the invention, in the stand-by position;
FIG. 2 depicts, in a similar manner, the apparatus during treatment;
FIG. 3 is a side-on view of the source/collimator assembly indicating the possible positions of the patient's head;
FIG. 4 is a front view of the subject of FIG. 3;
FIG. 5 depicts, in longitudinal section and on a larger scale, the region of the source/collimator assembly associated with a source;
FIG. 6 illustrates, in perspective, the set of channels associated with a source;
FIG. 7 is a view taken in the direction of FIG. 5; and
FIG. 8 illustrates, by means of a diagram, the energy-flux distribution in the vicinity of the focusing point.
DETAILED DESCR
REFERENCES:
patent: 4780898 (1988-10-01), Sundqvist
patent: 5528653 (1996-06-01), Song et al.
Search Report FR 93 06787 1994.
Atea, Societe Atlantique de Techniques Avancees
Bruce David Vernon
Porta David P.
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