Development and characterization of optical readout well-type glass gas electron multiplier for dose imaging in clinical carbon beams

The use of carbon ion beams in cancer therapy (also known as hadron therapy) is steadily growing worldwide; therefore, the demand for more efficient dosimetry systems is also increasing because daily quality assurance (QA) measurements of hadron radiotherapy is one of the most complex and time consuming tasks. The aim of this study is to develop a two-dimensional dosimetry system that offers high spatial resolution, a large field of view, quick data response, and a linear dose-response relationship. We demonstrate the dose imaging performance of a novel digital dose imager using carbon ion beams for hadron therapy. The dose imager is based on a newly-developed gaseous detector, a well-type glass gas electron multiplier. The imager is successfully operated in a hadron therapy facility with clinical intensity beams for radiotherapy. It features a high spatial resolution of less than 1 mm and an almost linear dose-response relationship with no saturation and very low linear-energy-transfer dependence. Experimental results show that the dose imager has the potential to improve dosimetry accuracy for daily QA.

Cellular and molecular portrait of eleven human glioblastoma cell lines under photon and carbon ion irradiation

This study aimed to examine the cellular and molecular long-term responses of glioblastomas to radiotherapy and hadrontherapy in order to better understand the biological effects of carbon beams in cancer treatment. Eleven human glioblastoma cell lines, displaying gradual radiosensitivity, were irradiated with photons or carbon ions. Independently of p53 or O(6)-methylguanine-DNA methyltransferase(1) status, all cell lines responded to irradiation by a G2/M phase arrest followed by the appearance of mitotic catastrophe, which was concluded by a ceramide-dependent-apoptotic cell death. Statistical analysis demonstrated that: (i) the SF2(2) and the D10(3) values for photon are correlated with that obtained in response to carbon ions; (ii) regardless of the p53, MGMT status, and radiosensitivity, the release of ceramide is associated with the induction of late apoptosis; and (iii) the appearance of polyploid cells after photon irradiation could predict the Relative Biological Efficiency(4) to carbon ions. This large collection of data should increase our knowledge in glioblastoma radiobiology in order to better understand, and to later individualize, appropriate radiotherapy treatment for patients who are good candidates.