Clinical study on 4D-CT combined with respiratory gating technology in stereotactic body radiotherapy for lung cancer

Objective To explore target size, dosimetric difference, adverse reactions and clinical efficacy of radiotherapy by 4D-CT combined with respiratory gating technique in stereotactic body radiotherapy (SBRT) for metastatic or primary lung cancer.

Methods The data of 32 patients (54 lesions) with metastatic or primary lung cancer treated in the Radiotherapy Center of Affiliated Hospital of Yangzhou University were collected. The CT data was processed by 4D software program, and 10 groups of CT images were obtained. Respiratory gating plan and conventional radiotherapy plan were made for them. The target volume and dose of the two plans were compared, and the adverse reactions and efficacy of radiotherapy were observed within 3 months after treatment.

Results Compared with the conventional plan, the volume of inner target area (ITV) and planning target area (PTV) under respiratory gating plan was smaller, and the dose received by 95% of PTV (D₉₅) was higher(P < 0.05). The percentage of volume of normal lung tissue exposed to radiation doses greater than 20 Gy (V₂₀), the percentage of volume of normal lung tissue exposed to radiation doses greater than 5 Gy (V₅), mean dose of bilateral lung (MLD) and dose of spinal cord for 1 cm³ volume (D_1cc) under the respiratory gating plan were significantly lower than those under the conventional plan (P < 0.05). The follow-up results showed that the incidence rate of grade 1 and 2 radiation pneumonia was 25.0%, and the total effective rate was 65.6%.

Conclusion 4D-CT combined with respiratory gating technology can be applied to SBRT for lung cancer, especially for patients with multiple lung metastases. It can accurately track the location of multiple tumors, ensure the effectiveness and accuracy of treatment, and reduce the occurrence of adverse reactions in surrounding normal tissues.