Interfractional Variations of Tumor Centroid Position and Tumor Regression during Stereotactic Body Radiotherapy for Lung Tumor

Abstract

Purpose. To determine interfractional changes of lung tumor centroid position and tumor regression during stereotactic body radiation therapy (SBRT). Methods and Materials. 34 patients were treated by SBRT in 4-5 fractions to a median dose of 50 Gy. The CT scans acquired for verification were registered with simulation CT scans. The gross target volume (GTV) was contoured on all verification CT scans and compared to the initial GTV in treatment plan system. Results. The mean (±standard deviation, SD) three-dimension vector shift was 5.2 ± 3.1 mm. The mean (±SD) interfractional variations of tumor centroid position were −0.7 ± 4.5 mm in anterior-posterior (AP) direction, 0.2 ± 3.1 mm in superior-inferior (SI) direction, and 0.4 ± 2.4 mm in right-left (RL) direction. Large interfractional variations (≥5 mm) were observed in 5 fractions (3.3%) in RL direction, 16 fractions (10.5%) in SI direction, and 36 fractions (23.5%) in AP direction. Tumor volume did not decrease significantly during lung SBRT. Conclusions. Small but insignificant tumor volume regression was observed during lung SBRT. While the mean interfractional variations of tumor centroid position were minimal in three directions, variations more than 5 mm account for approximately a third of all, indicating additional margin for PTV, especially in AP direction.

Accumulation of the delivered dose based on cone-beam CT and deformable image registration for non-small cell lung cancer treated with hypofractionated radiotherapy

“…Previous studies found that the mean GTV reduction was about 19–51.1% in patients treated by conventional fractionated radiotherapy [ 22 – 25 ]. A less marked reduction in tumor volume was obtained during SBRT due to the short irradiation course, with the mean GTV reduction of 12.8–32% [ 26 , 27 ]. In current study, we detected a gradual shrinking of tumor volume over the course of treatment with median reduction of 11.1%, which suggested only a fraction of patients could benefit from ART.…”

Accumulation of the delivered dose based on cone-beam CT and deformable image registration for non-small cell lung cancer treated with hypofractionated radiotherapy

“…Previous studies found that the mean GTV reduction was about 19%-51.1% in patients treated by conventional fractionated radiotherapy [22][23][24][25]. A less marked reduction in tumor volume was obtained during SBRT due to the short irradiation course, with the mean GTV reduction of 12.8%-32% [26,27]. In current study, we detected a gradual shrinking of tumor volume over the course of treatment with median reduction of 11.1%, which suggested only a fraction of patients could bene t from ART.…”

Effects of Exercise Training and Weight Loss on Plasma Fetuin-A Levels and Insulin Sensitivity in Overweight Older Men

“…Furthermore, although lower fetuin-A levels were associated with greater CVD risk in nondiabetic people, in diabetic people, the opposite trend was observed [ 36 ]. Finally, a recent meta-analysis of 10 case-control studies including over 1200 patients with cardiovascular disease and 2600 healthy controls concluded that lower serum fetuin-A levels correlated with the development of cardiovascular disease [ 37 ]. Additional evidence suggests that there may be a sex-specific relationship between fetuin-A, VO 2max , and coronary artery calcification.…”