A novel intra pre-plan method of interstitial needle optimization for cervical cancer patients treated with Venezia applicator brachytherapy: a technical note.

Purpose: Novel hybrid Venezia applicator enables intracavitary and interstitial brachytherapy (BT) for locally advanced cervical cancer. However, the method to determine the optimal interstitial needle number, position, and depth using this applicator is unknown. Therefore, we aimed to establish a method for reliable needle optimization. Material and methods: We produced a template model of the Venezia applicator with whole needles, and acquired computed tomography (CT) images (template CT). Using this template CT as a map, clinicians could define interstitial needle's insertion route in advance. During treatment, we first placed tandem and ovoid, and acquired a CT (tandem + ovoid CT). This was fused to the template CT by matching the contour of applicators with high accuracy. Then, we determined the optimal interstitial needle number, position, and depth to fit high-risk clinical target volume (HR-CTV) and avoid organs at risk (OARs) on the fused CT (intra pre-plan). Next, we re-inserted the tandem and ovoids with interstitial needle into patient's uterus and vagina. We inserted the optimized interstitial needle using insertion tool of optimal depth immediately following the applicator insertion. Lastly, a real-time treatment planning CT was performed, followed by planning and treatment. Results: We achieved a good dose distribution of Venezia applicator BT using intra pre-plan method to optimize the number of interstitial needles, position, and depth. Conclusions: This novel intra pre-plan method of interstitial needle optimization using template CT fusion provides high reproducibility, efficiency, and safety for patients with cervical cancer treated with brachytherapy using Venezia applicator.

A comparison of clinical outcomes between three-dimensional conformal radiotherapy and intensity-modulated radiotherapy for prostate cancer.

BACKGROUND: Intensity-modulated radiation therapy (IMRT) reduces the dose delivered to organs at risk. However, there have been few direct comparisons of IMRT with conventional three-dimensional conformal radiotherapy (3DCRT). The aim of this study was to evaluate the clinical benefit of IMRT in terms of toxicity and biochemical control. METHODS: The medical records of 203 consecutive patients with localized to non-metastatic (stage T1a-T3bN0M0) prostate cancer between 2007 and 2011 were retrospectively reviewed. The prescribed dose was 76 Gy delivered in 38 fractions in both the 3DCRT and IMRT treatment groups. The frequency of grade 2 or greater late gastrointestinal (GI) and genitourinary toxicity and biochemical control were estimated by the log-rank test and Cox proportional hazards model with and without adjustment by the propensity score for treatment choice. RESULTS: A total of 159 patients were included in the study (3DCRT: 70 patients, IMRT: 89 patients). The median follow-up period was 4.7 years. The estimated 5-year cumulative risk of late GI toxicity was significantly lower in the IMRT group than in the 3DCRT group (3.6 vs 13.2%, respectively, p = 0.022). After adjustment by propensity score, IMRT remained associated with a lower risk of late GI toxicity (hazard ratio 0.22; 95% confidence interval 0.058-0.85; p = 0.028). The 5-year biochemical failure-free rate was 93.2% in the 3DCRT group and 95.4% in the IMRT group (non-significant difference). CONCLUSIONS: The incidence of late GI toxicity was significantly lower in the IMRT group than in the 3DCRT group, while the biochemical control rates were no different between the two groups. These clinical data suggest the benefit of IMRT in the reduction of late GI toxicity.