Synchrotron radiation therapy of malignant brain glioma loaded with an iodinated contrast agent: first trial on rats bearing F98 gliomas.

Abstract

Enhancement of the radiation dose delivered to a brain tumor can be achieved by infusing an iodinated contrast agent to the patient and irradiating with kilovoltage X-rays in computed tomography (CT) mode. Synchrotron sources, providing monochromatic tunable intense beams, are ideal for this treatment. The aim of this study is to assess in vivo the efficiency of this novel radiotherapy modality, Synchrotron Radiation CT-Therapy. Intracranial implantations of 10(5) F98 glioma cells were performed on 18 Fisher 344 rats. Six rats were untreated controls, six received radiotherapy alone (10 Gy in the tumor by single fraction tomographic irradiation at 50 keV), and six received the same radiotherapy treatment under a continuous infusion of iodinated contrast agent. The rats that received contrast agent during radiotherapy survived significantly longer than rats that received radiotherapy alone (p = 0.025). Mean survival times (mean +/- SD) were 12.3 +/- 0.8, 14.8 +/- 2.8, and 18.2 +/- 1.3 days; median survival times were 12.5, 15, and 18 days (untreated controls, irradiated without iodine, irradiated with iodine, respectively). The increase in life spans was 20% and 44% for the rats irradiated without or with iodine, respectively. This method of radiation dose enhancement in brain tumors with synchrotron radiation significantly increases survival and appears highly promising.