Research on radiotherapy target volumes for glioblastoma is increasingly focused on exploring more limited yet effective irradiation fields, aiming to achieve local control while minimizing acute and long-term neurotoxicity. Previous retrospective analysis by investigators revealed that local recurrences of glioblastoma are predominantly confined to a narrow margin around the original lesion: 98.3% of recurrences occurred within 0.5 cm of the original T2-FLAIR abnormality, 94.8% within 1 cm of the original T1-enhanced region. These findings have been cited in the ESTRO-EANO treatment guidelines. Building on this evidence, investigators plan to conduct a single-arm, phase II clinical trial to systematically evaluate the efficacy and safety of a 1 cm radiotherapy target volume in post-operative glioblastoma patients.Eligible patients with glioblastoma who have undergone surgical resection will be selected to receive limited-field radiotherapy. The target volume will be defined based on the postoperative MRI enhancing lesion: a 1 cm margin will be added to form the clinical target volume (CTV), followed by a further 0.3 cm margin to create the planning target volume (PTV). A total dose of 60 Gy will be delivered in 30 fractions (2 Gy per fraction, 5 fractions per week). Concurrent and adjuvant chemotherapy will be administered per standard guidelines. The primary efficacy endpoints are the 6-month progression-free survival rate and the incidence of symptomatic radiation-induced brain necrosis of grade 3 or higher. Secondary endpoints include overall survival, patterns of recurrence, neurocognitive function, and quality of life.

Inclusion Criteria:

• Aged between 18 and 70 years.
• Diagnosed with glioblastoma by surgical pathology, with the extent of resection achieving maximal safe resection.
• Within 2 to 6 weeks after surgery
• In good physical condition with a Karnofsky Performance Status (KPS) score ≥ 60.
• Hematological, hepatic, and renal functions are essentially normal.
• Signed informed consent, willing to undergo treatment and follow-up as stipulated in the study protocol.

Exclusion Criteria:

• Prior history of cranial radiotherapy or other malignant tumors.
• Severe dysfunction of vital organs (e.g., heart, liver, kidneys) that precludes tolerance to radiotherapy.
• Active infection, immune system disorders, or other serious chronic diseases.
• Pregnancy or lactation.
• Psychiatric disorders or severe cognitive impairment that compromises the ability to cooperate with treatment and follow-up.