Abstract
Hintergrund
In der klinischen Praxis gibt es immer wieder Fälle, bei denen mit konventionellen Methoden keine zufriedenstellende Dosisverteilung erzielt werden kann. Für diese Fälle können die inverse Bestrahlungsplanung und eine Strahlentherapie mit intensitätsmodulierten Feldern möglicherweise eine Lösung bieten.
Methode
Bei der inversen Bestrahlungsplanung wird mit Hilfe eines Computeralgorithmus automatisch ein Bestrahlungsplan erzeugt, der den Vorgaben des Arztes entspricht. Die Vorgaben können entweder dosisabhängig sein, wie zum Beispiel Minimal- und Maximaldosen in Zielvolumina und Risikoorganen, oder sie können auf medizinisch-biologischen Modellen basieren, wie der komplikationsfreien Tumorheilung. Als Resultat der inversen Planung erhält man nach Vorgabe der Anzahl und Einstrahlrichtung die Fluenzverteilung der entsprechenden Strahlenfelder. Diese Fluenzverteilungen können mit Kompensatoren bzw. Multi-Leaf-Kollimatoren erzeugt werden.
Ergebnisse
Erste klinische Studien mit optimierten intensitätsmodulierten Bestrahlungstechniken werden bereits durchgeführt. Es hat sich gezeigt, daß die Technologie beherrschbar ist und die erreichbaren Dosisverteilungen in bezug auf Tumorkonformität denen konventioneller Methoden überlegen sind.
Schlußfolgerung
Die inverse Bestrahlungsplanung mit intensitätsmodulierten Feldern wird bei weiterer Verbesserung der Technologie sicher bei ausgewählten klinischen Fällen mehr und mehr eingesetzt werden.
Abstract
Background
In clinical practice it sometimes happens that with currently available conformai radiotherapy techniques no satisfactory dose distribution can be achieved. In these cases inverse radiotherapy planning and intensity modulated radiotherapy may give better solutions.
Method
Inverse planning is a technique using a computer program to automatically achieve a treatment plan which has an optimal merit. This merit may either depend on dose or dose-volume constraints like minimum and maximum doses in the target region or critical organs, respectively, or biological indices like the complication free tumor control rate. As the result of inverse planning the inhomogeneous intensity fluence of the beams is calculated. These fluence distributions may be generated by beam compensators or multi-leaf collimation.
Results
Clinical studies to prove the advantage of inverse planning are already on the way. It has been shown that this technology is safe and that the dose distributions which can be achieved are superior to conventional methods.
Conclusions
Inverse treatment planning and intensity modulated radiation therapy will almost certainly come to be the technique of choice for selected clinical cases.
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Schlegel, W., Kneschaurek, P. Inverse bestrahlungsplanung. Strahlentherapie und Onkologie 175, 197–207 (1999). https://doi.org/10.1007/BF02742396
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DOI: https://doi.org/10.1007/BF02742396