Dosimetric impact of a frame-based strategy in stereotactic radiotherapy of lung tumors

Figures & data

Table I. Patient and tumor characteristics.

Number of patients	N = 30
Number of fractions	n = 90
Sex	M: 15; F: 15
Diaphragm control	Yes: 3; No: 27
Diagnosis	Primary lung tumors: 27 Lung metastasis: 3
Closest distance to spinal cord	118 mm (54–196 mm)
Tumor location	RUL: 11 RML: 0 RLL: 3 LUL: 13 LLL: 3

Table II. Characteristics of the initial dose plans. Median values are given, with ranges in brackets.

Volume GTV	5.4 cm^3 (0.6–38.8 cm^3)
Volume ITV	19.5 cm^3 (4.8–85.7 cm^3)
Volume PTV	47.0 cm^3 (16.3–151.6 cm^3)
PTVmin	45.0 Gy
ITVmin	54.1 Gy (48.8–57.4 Gy)
PTVmax	68.3 Gy (65.5–98.4 Gy)
Conformity Index (V100/VPTV)	1.32 (1.10–1.82)

Figure 1. Registered displacement of the target according to the initial set-up in the SBF compared to the planning CT, as obtained from the CT-CBCT registration. Results in the vertical, lateral and longitudinal directions are displayed for all treatment fractions, 90 in total.

Figure 2. Example of the four plans for a patient. The target volumes appear as solid lines in the axial view and as dotted lines in the reconstructed sagittal and coronal views. Dose isoshades are also displayed in the slices, where the yellow isoshade is the prescription dose (15 Gy).

Figure 3. Minimum doses to the ITV for all four plans for all patients. The 15 Gy level indicates the prescription dose.

Figure 4. The ITV minimum dose as a function of the absolute displacement vector. Results for all treatment fractions (n = 90) are displayed, where three fractions are summed for each patient (N = 30).