Image guidance improves gain ratio in radioactive seeds brachytherapy

Abstract

Objective To investigate whether quality assurance and quality control using multimodal image guidance and radiation dosimetry optimization could ensure and improve the targeting of 125I seeds brachytherapy. Methods A total of 287 patients (184 males, 103 females, average age 61.9 years) with non-small-cell lung cancer (NSCLC) and 122 patients (average age 65.5 years) with prostate cancer who were diagnosed by pathology or imaging methods(coincidence imaging, CT, flexible fiberoptic bronchoscopy, ultrasonography) from October 2002 to October 2016 were retrospectively enrolled. All imaging methods were used to locate the target area. Optimization of radiation dosimetry was made according to treatment planning system (TPS) and evaluated by dose-volume histogram (DVH). 125I seeds implantation was performed under the imaging guidance, followed by real-time location verification, dosimetric verification. Therapeutic efficacy was evaluated. Paired t test was used to analyze the data. Results The prescribed dose (PD) of planning target volume (PTV) was above 140 Gy. Immediate dosimetric verification was performed in 59 patients with NSCLC and 31 patients with pulmonary metastases. The radiation dose before and after the implantation was coincident in 93.2%(55/59) of NSCLC and 93.5%(29/31) of pulmonary metastases. The coincident rate of patients with dose delivered to 90% GTV (D90)>matched peripheral dose (MPD) was 93.2%(55/59) and 87.1%(27/31) respectively in NSCLC and pulmonary metastases. There was no significant difference in MPD, D90 and conformity index (CI) before and after implantation (t values: 2.11-9.71, all P>0.05). The average dose of the risk organs was significantly lower than the tolerance dose of the normal tissue. The incidence of radiation pneumonitis was 1.05%(3/287). No other serious complications were found. Conclusion Targeted diagnosis and therapy of multimodal image guidance could be optimized to improve the effect of targeting and therapeutic gain ratio of 125I seeds brachytherapy. Key words: Carcinoma, non-small-cell lung; Radiotherapy, image-guided; Brachytherapy; Iodine radioisotopes