The combination of anatomical MRI examination with functional examination of tissue metabolic activity such as FET-PET (PET using the radiotracer - 18F-fluoro-ethyl-tyrosine) is a valuable tool to determine the actual tumor infiltration. The FET-PET examination can be performed using the dual-time point aqusition of FET for exact treatment planning. It has also been proven that using the dual FET-PET method, it is possible to obtain a precise image of the glioblastoma infiltration corresponding to the location and shape of the recurrence, and the tumor volumes in dual FET-PET are significantly larger than in MRI. Moreover, tumor defined in dual FET-PET is different than that of the tumor defined in single FET-PET acquisition.

In the DualFETboosT trial we plan to assess the safety and preliminary efficacy of hypofractionated irraditon using simultaneous in-field boost directed on dual FET-PET based tumor volumes for treatment of primary glioblastoma multiforme with concomitant temozolomide.

In the case of the treatment of glioblastoma multiforme, as a standard, radiotherapy lasts 6 weeks, and the extension of treatment may adversely affect the tumor cells death, the patient's well-being and treatment costs (prolonged hospitalization). In turn, escalating the dose may increase the toxicity of radiation therapy by increasing DNA damage in healthy brain tissue. Using of dual FET-PET images for treatment planning allow to reduce volumes of healthy tissue irradiated. Dose-intensification proposed in the study using simultaneous in-field boost allows the dose escalation without increasing the overall treatment time. All patient will be treated with moderately hypofractionated radiotherapy (2.6 Gy per fraction) directed on PET positive volumes and conventional fractionation (60Gy in 30 fractions) on tumor margin.

Inclusion Criteria:

• Histopathological confirmation of glioblastoma (WHO grade IV)
• Age between 18-75 years of age
• General condition according to the Zubrod scale 0 or 2
• The results of the blood counts are normal
• Liver enzyme parameters normal
• The results of the parameters of the patient's functions are normal
• Informed consent to participate in the category

Exclusion Criteria:

• Coexistence of another cancer
• The location of the tumor in the area of the brain stem or cerebellum
• Prior brain radiation therapy
• No uptake visible in the FET-PET imaging
• Contraindications for MRI
• Contraindications to radiotherapy or chemotherapy
• Pregnancy, lack of consent to the use of protection against pregnancy, puerperium
• Alcohol addiction
• Mental illness
• Claustrophobia