Enhanced radio sensitivity with iodinated contrast agents using monochromatic synchrotron X-rays on human cancerous cells
As stressed by clinicians (1), therapy of high grades brain gliomas can be considered as a model of therapeutic failure. Despite research efforts in many therapeutic domains, high grades gliomas are of poor prognosis. Radiation therapy is commonly used for these patients but a limiting factor of this tool is the difficulty to deliver high therapeutic dose of ionizing radiation to the tumour volume without exceeding normal tissue tolerance. In conventional external radiotherapy, the treatment of brain tumors is a delicate challenge because of energy deposit to surrounding healthy tissues. One strategy is to enhance x-rays dose deposition inside the tumor while sparing surrounding tissues, owing to injection of a contrast agent to the patient (2,3). It is possible to use computerized tomography scanner to deliver highest doses in the targeted tissue by using infused contrast material (4-6). The goal of any x-ray contrast material is to produce a gradient in cross-sections leading to a gradient in photon flux measured by the imaging device detector. The energy deposit in the vicinity of the contrast material has been assessed (2,7). Contrast agent accumulates in the tumor interstitium which is irradiated with diagnostic x-rays (lower than 150 keV) by means of a conventional scanner. The increase of dose deposit in the tumor, with regard to healthy tissues, results from the combination of two effects:
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