Table 6.

Documentation of rib doses in MC lung SBRT plans calculated by iPlan XVMC algorithm. First 5 patients had dose delivery schema of total 54 Gy in 3 fractions, and remaining 15 patients with 50 Gy in 5 fractions. For the 1st 5 patients who were treated for a total dose of 54 Gy in 3 fractions, the 3D distance from the tumor isocenter to the proximity of the rib contour was more than 5 cm, except for one patient who had relatively small PTV (20.1 cc, Patient #2), it was 3.5 cm and the associated maximum point dose to ribs was 59.3 Gy.

Patient No.	PTV Vol. (cc)	Maximum Rib Dose (Gy)	Dose to $<1\hspace{0.17em}\text{cc}$ of Ribs (Gy)	Dose to $<5\hspace{0.17em}\text{cc}$ of Ribs (Gy)	Dose to $<10\hspace{0.17em}\text{cc}$ of Ribs (Gy)	Isocenter to Proximal Rib Contour Distance in 3D (cm)
1	11.1	41.8	30.2	21.4	12.6	5.6
2	20.1	59.3	42.5	32.2	25.7	3.5
3	27.1	33.1	27.9	25.3	22.2	6.9
4	50.9	45.6	38.7	31.5	27.7	5.4
5	68.1	38.4	33.1	30.5	27.3	7.0
6	12.9	55.5	36.9	10.6	1.1	1.5
7	15.0	54.5	47.9	30.3	20.9	1.7
8	20.1	54.6	44.6	25.7	2.0	1.6
9	21.0	54.4	47.9	28.7	17.4	1.7
10	26.3	53.3	43.5	32.1	24.3	3.9
11	31.2	53.6	42.4	31.4	20.6	3.6
12	36.2	54.1	45.1	32.6	22.9	3.0
13	37.1	51.5	44.7	32.1	23.2	4.4
14	39.7	49.5	42.4	28.1	17.3	5.4
15	39.8	52.4	45.9	33.3	23.3	2.8
16	53.4	54.4	45.8	43.1	28.9	3.6
17	56.5	54.9	44.6	40.6	18.3	3.3
18	61.5	53.3	43.9	36.9	33.6	4.0
19	132.0	52.8	42.4	36.6	19.7	5.0
20	163.0	52.3	42.8	41.6	35.9	5.2
AVG	46.1	50.9	41.6	31.2	21.2	4.0
STDEV	38.7	6.4	5.6	7.3	8.7	1.7

Note: Rib dose values ranged from 35.1 to 59.3 Gy for maximum rib dose ($\text{mean}=50.9\pm 6.4\hspace{0.17em}\text{Gy}$) and 27.9 to 47.9 Gy for dose to $<1\hspace{0.17em}\text{cc}$ of ribs ($\text{mean}=41.6\pm 5.6\hspace{0.17em}\text{Gy}$), respectively; the dose to $<10\hspace{0.17em}\text{cc}$ of ribs was less than 36 Gy (Patient #20, who had the largest PTV). The RTOG 0915 suggested doses limit for maximum rib dose $<40\hspace{0.17em}\text{Gy}$, and dose to $<1\hspace{0.17em}\text{cc}$ of ribs $<32\hspace{0.17em}\text{Gy}$ for a total prescription dose of 48 Gy in 4 fractions.

PTV = planning target volume; AVG = average; STDEV = standard deviation.