Anterior-oriented proton beams for prostate cancer: A multi-institutional experience

Figures & data

Table I. Patient characteristics.

Age	Median	69 (57–83)
	< 65	5 (25%)
	≥ 65	15 (75%)
PSA	Median	5.04 ng/ml
	< 10 ng/ml	18 (90%)
	10–20 ng/ml	2 (10%)
	> 20 ng/ml	0 (0%)
T stage	T1–T2a	19 (95%)
	T2b–T2c	1 (5%)
Gleason score	< 7	10 (50%)
	3 + 4 = 7	4 (20%)
	4 + 3 = 7	4 (20%)
	> 7	2 (10%)

Figure 1. Dose distribution and beam arrangement of patients treated with a lateral- and anterior-oriented beam (A and B) and laterally oriented beams (C and D). (A) CT slice demonstrating trajectory of anterior-oriented beam through the bladder. (B) CT slice demonstrating trajectory of anterior-oriented beam through isocenter. (C) CT slice demonstrating trajectory of lateral beams through the bladder. (D) CT slice demonstrating trajectory of lateral beams through isocenter. (Green color wash: Bladder. Brown color wash: Rectum. Red color wash: PTV).

Figure 2. Dose volume histograms of a patient treated with a lateral- and anterior-oriented beam (A) and a patient treated with lateral beams (B).

Table II. Median target coverage and dose to OARs.

Dose parameter	Anterior-oriented beams	Lateral beams
PTV D95	79.2 Gy (RBE) (69.7–79.9)	79.2 Gy (RBE) (78.4–79.5)
PTV V98	99.9% (98.5–100)	99.9% (99.6–99.9)
Rectum V70	9.2% (2.5–15.4)	6.8% (3.4–14.0)
Bladder V50	12.4% (3.7–27.1)	15.6% (2.7–24.8)
Bladder V80	3.5 cm^3 (0–7.1)	5.4 cm^3 (1.7–11.3)
Mean bladder dose	14.9 Gy (RBE) (4.6–37.8)	15.2 Gy (RBE) (2.9–23.2)
Femoral head V45	0.01 cm^3 (0–16.6)	0.0 cm^3
Femoral head MPD	43.7 Gy (RBE) (15.6–52.5)	36.80 (RBE) (34.8–40)

Table III. Toxicity.

	Grade 1 N (%)	Grade 2 N (%)	Grade 3 N (%)	Grade 4 N (%)
Acute urinary toxicity	9 (45)	8 (40)	0 (0)	0 (0)
Acute gastrointestinal toxicity	5 (25)	0 (0)	0 (0)	0 (0)
Acute erectile dysfunction	1 (5)	1 (5)	0 (0)	0 (0)
Hip toxicity (pain, fracture)	5 (25)	0 (0)	0 (0)	0 (0)