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Updated: Jun 16, 2026
Dynamic Lung Tumor Tracking for Stereotactic Ablative Body Radiation Therapy
Published on: June 7, 2015
Robustness of Tumor Control Against Intrafraction Patient Motion in Lung Stereotactic Body Radiation Therapy
Yohan A Walter1,2, Chiachien J Wang1, Daniel B Speir1
1Department of Radiation Oncology, Willis Knighton Cancer Center, Shreveport, Louisiana.
Purpose:
In stereotactic body radiation therapy (SBRT), patient motion during treatment may significantly impact the tumor control probability. In this study, we performed an analysis of patient outcomes to determine the clinical robustness of our lung SBRT protocols against patient motion and to assess the overall efficacy of our unique treatment delivery technique.
Methods And Materials:
Seventy-eight patients treated for 85 primary lung tumors or lung metastases using SBRT were included. An abdominal compression belt was used for respiratory motion management. Prescription doses were 50 to 70 Gy, delivered in 5 fractions. Our standard planning target volume expansion was 5.0 mm. Image guided positional corrections were performed halfway through treatment. Intrafraction shifts were recorded for analysis. Kaplan-Meier analysis was performed to determine the 2-and 3-year local control (LC) and overall survival. Adverse effects were evaluated using the National Cancer Institute Common Terminology Criteria for Adverse Events version 6.0.
Results:
The median follow-up duration was 25 months (IQR, 13-40 months). Course-averaged intrafraction patient motion ranged from 1.2 to 8.2 mm (median, 3.5 mm; IQR, 2.5-4.0 mm). The 2-and 3-year LC (95% confidence interval) were 97.6% (83.9%-99.7%) and 94.0% (77.3%-98.5%), respectively. The 2-and 3-year overall survival were 77.3% (65.8%-87.8%) and 69.6% (56.8%-79.3%), respectively. The 2 local recurrences were observed at 22 and 31 months post-SBRT. They were associated with the 33rd largest and the smallest average repositioning shifts in the study. No adverse events of grade ≥3 were observed over the study interval.
Conclusions:
The excellent LC rates observed irrespective of patient positioning uncertainty were demonstrative of the clinical robustness of our SBRT workflow and may support future studies investigating planning target volume margin reduction. High efficacy and low incidence of adverse events support the implementation of this workflow in clinics developing SBRT programs. Similar study designs may be used to assess alternative SBRT workflows.
