Genauigkeit und lokale Kontrolle der kontinuierlichenextrakraniellen Radiochirurgie am Beispielintrapulmonaler Tumore
Fragestellung: Literaturdaten belegen, dass mittels stereotaktischen Standardmethoden hohe lokale Kontrollraten mit geringem Nebenwirkungsrisiko ermöglicht werden können. Dazu werden in erster Linie eine extrem hohe Präzision der Patientenlagerung und der Dosisapplikation gefordert, um durch höhere...
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Introduction: In literature it has been shown that a high local control for small intrapulmonal tumours is reached with a precise patient supposition and an exact application of the total dose. To lead a lethal dose into the tumour a time consuming and conformal treatment planning is necessary. Before treatment the patients experienced a second CT to get repositioned. After this CT-study a setup-vector has to be determined to calculate the difference between the two CT. In literature this value is about 6,0 – 6,8 mm. In this paper we tried to optimize the published methods to reach a faster but conformal stereotactic radiotherapy. Material and method: We tested a new method of an extracranial radiotherapy to treat patients with medical non-small cell lung cancer (NSCLC) or single metastases of the lung. They all had contraindications for or refused surgery. The patients were immobilised only once; for planning-CT, treatment planning and radiation with a vacuum body cast and an abdominal press, fixed on a steretactic body frame. Patients could be treated even of a bad lung function because no special breathing exercises are necessary and the total procedure needs only less than 2 hours so that a tolerable position was confirmed by all of them. Results Because of the patient’s continuous positioning we avoided a deviation of the body and so a second CT for repositioning. Virtual treatment-planning using a planning library, auto-segmentation and a fast planning system were the conditions for an optimized therapy for peripheral lung tumours. During the treatment we controlled – using a film option of the portal imaging system – the intrathoracical tumour movement by using DRRs, produced with the planning-CT. The result of this method was 59 a small setup-vector which showed a reduced patient’s movement during therapy so that a moving target could be radiated successfully. Conclusion Disease free survival and overall survival without worse secondary effects are comparable with the literature so that this new method is a fast and efficient therapy for patients with peripheral intrapulmonal and inoperable tumours.