Optimal beam arrangement for stereotactic body radiation therapy delivery in lung tumors

Figures & data

Table I. Patients’ characteristics (n=37).

Age	35–86 years (median 71 years)
Sex
Male	27 (73.0%)
Female	10 (27.0%)
Tumor size
<3 cm	24 (64.9%)
3–5 cm	13 (35.1%)
Tumor diameter (mm)	10–55 (median 30mm)
PTV volume (cc)	9.2–112.6 (median 30.7 cc)

Table II. Major and minor deviations according to RTOG 0236 criteria from all 12 plans per each patient (n=37).

Criteria	Major deviation	Minor deviation	Total deviation
1. Prescription surface isodose coverage	0	0	0
2. High dose volume - conformality index	0	2 (5.4%)	2 (5.4%)
3. Low dose volume
- R50%	32 (86.5%)	27 (73.0%)	37 (100%)
- D2cm	2 (5.4%)	8 (21.6%)	9 (24.3%)
4. Critical organ dose limit			2 (5.4%)

Table III. Major and minor deviations according to R_50% criteria from all 12 plans per each patient and from the best plan within each of three treatment techniques.

R50%	Major deviation	Minor deviation	No deviation
1. All plans
- multiple coplanar static beams	27 (73.0%)	9 (24.3%)	1 (2.7%)
- multiple non-coplanar static beams	25 (67.6%)	11 (29.7%)	1 (2.7%)
- arc therapy	25 (67.6%)	12 (32.4%)	0 (0.0%)
2. Best plan
- multiple coplanar static beams	22 (59.5%)	13 (35.1%)	2 (5.4%)
- multiple non-coplanar static beams	9 (24.3%)	17 (45.9%)	11 (29.7%)
- arc therapy	25 (67.6%)	12 (32.4%)	0 (0.0%)

Table IV. Mean and standard deviation (SD) values of R_50% according to plans (n=37).

Number of beams	Mean±SD	p
Multiple coplanar static beams		0.2640^a*
7	4.0765±0.3513
9	4.0332±0.3266
11	4.0096±0.3153
13	3.9983±0.3131
15	4.0000±0.3176
Multiple non-coplanar static beams		<0.0001^b*
2 non-coplanar beams
7	3.8623±0.1867
9	3.8613±0.1468
11	3.8694±0.0873
4 non-coplanar beams
7	4.1052±0.9709
9	3.9580±0.2809
11	3.9327±0.2038

a) Pearson correlation; number of beams vs. R_50%.

b) Paired t-test; 2 non-coplanar beams vs. 4 non-coplanar beams according to number of beams.