Dosimetric analysis of rib interference of the CTV during interstitial brachytherapy of lung tumors

Template-assisted 192Ir-based stereotactic ablative brachytherapy as a neoadjuvant treatment for operable peripheral non-small cell lung cancer: a phase I clinical trial

Purpose

To evaluate safety, feasibility, and efficacy of template-assisted ¹⁹²Ir-based stereotactic ablative brachytherapy (SABT), combined with surgery for peripheral non-small cell lung cancer (NSCLC).

Material and methods

Patients with pathologically confirmed operable peripheral NSCLC, who underwent template-assisted SABT (30 Gy delivered in one fraction) and were scheduled for tumor resection 4-6 weeks after SABT were included in this study. The perioperative adverse reactions of SABT were recorded to evaluate safety and feasibility of SABT for neoadjuvant therapy. Dosimetric data from both simulated and actual plans were collected and compared. Imaging with ¹⁸F-fluorodeoxyglucose-positron emission tomography/computed tomography (¹⁸F-FDG-PET/CT) and dynamic contrast-enhanced computed tomography were scheduled before SABT and surgery to evaluate the efficacy of the neoadjuvant therapy with SABT.

Results

Patients did not experience any serious adverse events. None of the patients had a delay in receiving surgery. After 4-6 weeks, the indicators for the efficacy of neoadjuvant therapy significantly decreased in all patients: gross tumor volume (p < 0.001), maximum standardized uptake value (p < 0.001), tumor blood volume (p < 0.001), and tumor blood flow (p = 0.008). Dosimetric parameters in the delivered SABT plan slightly changed from the preoperative simulation, but the difference was not statistically significant (p > 0.05).

Conclusions

The efficacy of template-assisted SABT for neoadjuvant therapy was significant in operable peripheral NSCLC. Moreover, no serious adverse reactions were observed; when the coplanar template guidance technique was applied, dosimetric parameters were in good agreement between the actual SABT plan and the preoperative simulated plan.

Single fraction computed tomography-guided high-dose-rate brachytherapy or stereotactic body radiotherapy for primary and metastatic lung tumors?

PURPOSE

To provide a pilot dosimetric study of computed tomography (CT)-guided high-dose-rate (HDR) brachytherapy (BRT) and stereotactic body radiotherapy (SBRT) for primary and metastatic lung lesions.

MATERIAL AND METHODS

For nine lung primary and metastasis patients, 3D image-based BRT plan using a single virtual catheter was planned for 34 Gy in single fraction to the gross tumor volume (GTV) + 3 mm margin to account for tumor deformation. These plans were compared to margin-based (MB-) and robustness optimized (RO-) SBRT, assuming the same tumor deformation under real-time tumor tracking. Consistent dose calculation was ensured for both BRT and SBRT plans using the same class of collapsed cone convolution superposition algorithm. Plan quality metrics were compared by Friedman tests and Wilcoxon t-tests.

RESULTS AND CONCLUSIONS

Brachytherapy plans showed significant higher GTV mean dose compared to MB- and RO-SBRT (122.2 Gy vs. 50.4 and 44.7 Gy, p < 0.05), and better dose gradient index (R50) = 2.9 vs. 4.3 and 8.4 for MB- and RO-SBRT, respectively. Dose constraints per the RTOG 0915 protocol were achieved for all critical organs except chest wall in BRT. All other dose-volume histograms (DVH) metrics are comparable between BRT and SBRT. Treatment delivery time of BRT and SBRT plans significantly increased and decreased with increasing GTV size, respectively. SBRT using advanced MLC tracking technique and non-coplanar VMAT can achieve comparable dosimetric quality to HDR BRT. Whether or not, the significantly higher GTV dose can increase killing of radioresistant tumor cells and offset the effect of tumor reoxygenation in single fraction BRT, requires further clinical investigation.

Effectiveness and safety of a robot-assisted 3D personalized template in 125I seed brachytherapy of thoracoabdominal tumors

PURPOSE

This research aims to evaluate the effectiveness and safety of a robot-assisted 3D personalized template in 125I seed brachytherapy of thoracoabdominal tumors.

MATERIAL AND METHODS

Forty-three patients with different tumors were involved in this research between 2013 and 2015. They were all eligible to 125I seed implantation based on robot-assisted 3D personalized template. Meanwhile, 51 patients with similar tumors, which were treated with a conventional coplanar template, were involved for comparison. Follow-up was carried out after the surgery to evaluate the therapeutic efficacy, including overall survival (OS) of the patient and local control (LC) of the tumor. Complications were also summarized to evaluate the safety. Besides, statistical analysis was achieved to investigate possible factors associated with the result.

RESULTS

In the robot-assisted 3D personalized template-guided brachytherapy, the median target volume treated by the prescription dose (V100) was 95.3% (range, 92.4-109.8), and the median dose administered to 90% of the target volume (D90) was 126.1 Gy (range, 114.2-132.0), improved 5% and 8% compared with the conventional template-guided brachytherapy, respectively. The median OS was 30 months (95% CI: 19.4-40.6) and the rates of 2-year OS and LC were 58.1% and 86.0%, respectively. The median OS was prolonged 10 months and the 2-year OS and LC were improved 18.9% and 23.3% compared with the conventional template-guided brachytherapy, respectively.

CONCLUSIONS

Through analysis of the selected patients with thoracoabdominal tumors, the robot-assisted 3D personalized template in 125I seed brachytherapy was a more effective and safer method. It can achieve a more favorable OS and LC.