PROGNOSTIC FACTORS FOR DEEP SITUATED MALIGNANT GLIOMAS TREATED WITH LINAC RADIOSURGERY

Objective To study the function of radiosurgery on malignant glioma by analyzing prognostic factors affecting malignant gliomas treated with linac radiosurgery. Method Fifty-eight patients with deep situated malignant gliomas, aged 7 to 70 years, 28 anaplastic astrocytomas and 30 glioblastomas multiforme were analyzed. The median volume of tumor was 10.67 cm3, and median prescription dose for linac radiosurgery was 20 Gy. Results were analyzed with Kaplan-Meier curve and Cox regression. Result In follow-up 44.8 percent tumors (26 patients) decreased in size. Median tumor local control interval was 10 months, 15 months for anaplastic astrocytomas, and 9 months for glioblastoma multiforme. Tumor local control probability was 37.9 percent for 1 year and 10.3 percent for 2 years. Median survival was 22.5 months for anaplastic astrocytoma, 13 months for glioblastoma multiforme, and 15 months for all patients. The survival probability was 79.3 percent at 1 year and 20.6 per-cent at 2 years. Isocenter numbers and tumor volume were the prognostic factors for tumor control, but conformity index was the prognostic factor for survival by Cox regression analysis. Considering pathology, only isocenter number and target volume significantly affected tumor control interval. Complications appeared in 44.8 percent patients and the median interval of com-plication onset was 8 months. Symptomatic cerebral edema was observed in 31.0 percent patients. Conclusion Linac radiosurgery can effectively improve tumor local control and prolong survival for deep situated mali-gnant gliomas.

Accreting He-rich material onto carbon-oxygen white dwarfs until explosive carbon ignition

Type Ia supernovae （SNe Ia） play an important role in studies of cosmology and galactic chemi- cal evolution. They are believed to be thermonuclear explosions of carbon-oxygen white dwarfs （CO WDs） when their masses approach the Chandrasekar （Ch） mass limit. However, it is still not completely under- stood how a CO WD increases its mass to the Ch-mass limit in the classical single-degenerate （SD） model. In this paper, we studied the mass accretion process in the SD model to examine whether the WD can explode as an SN Ia. Employing the stellar evolution code called modules for experiments in stellar as- trophysics （MESA）, we simulated the He accretion process onto CO WDs. We found that the WD can increase its mass to the Ch-mass limit through the SD model and explosive carbon ignition finally occurs in its center, which will lead to an SN Ia explosion. Our results imply that SNe Ia can be produced from the SD model through steady helium accretion. Moreover, this work can provide initial input parameters for explosion models of SNe Ia.