Acute radiation-induced toxicity of heavy ion radiotherapy delivered with intensity modulated pencil beam scanning in patients with base of skull tumors

Abstract

Purpose: The purpose of this paper is to evaluate acute radiation-induced toxicity of carbon ion therapy.

Material and methods: From December 1997 to November 2000, 37 patients with chordomas and low-grade chondrosarcomas of the skull base have been treated with carbon ions at the heavy ion synchrotron (SIS) at GSI, Darmstadt. Tumor-conformal application of carbon beams was realized by intensity-controlled raster scanning in combination with pulse-to-pulse energy variation. The treatment planning procedure included a biological plan optimization. We applied a cobalt-Gray equivalent dose of 60GyE. Acute toxicity was assessed according to the common toxicity criteria (CTC).

Results: Acute toxicity included skin reactions ( degrees I+ degrees II) in four patients, mucositis ( degrees I- degrees III) in eight patients, otitis and middle ear effusion in four, sinusitis in four, nausea/weight loss in one and edema of the temporal lobes in one patient. In two patients, preexisting neurological symptoms worsened. We did not observe acute morbidity > degrees III of normal tissues.

Conclusion: Scanning beam delivery of heavy charged particles is safe and reliable. No unexpected acute dose limiting toxicity was observed. With regard to toxicity, a substantial improvement compared to passive beam shaping technology is achieved.