Optimal set of grid size and angular increment for practical dose calculation using the dynamic conformal arc technique: a systematic evaluation of the dosimetric effects in lung stereotactic body radiation therapy

Park, Ji-Yeon; Kim, Siyong; Park, Hae-Jin; Lee, Jeong-Woo; Kim, Yeon-Sil; Suh, Tae-Suk

doi:10.1186/1748-717X-9-5

Table 3 Monitor units (MUs) and structure doses in the form of a ratio normalized to a reference value from the case of a 2-mm grid size and 2° angular increment, when different plan parameter sets (grid sizes of 2 mm, 3 mm, and 4 mm, and angular increments of 2°, 4°, 6°, and 10°) were used in patient groups divided according to the equivalent diameter (d_equi) of the planning target volume (PTV)

From: Optimal set of grid size and angular increment for practical dose calculation using the dynamic conformal arc technique: a systematic evaluation of the dosimetric effects in lung stereotactic body radiation therapy

Patient	∆Angle/∆Grid	MU	PTV (D_mean)	Heart (D_max)				Normal Lung (D_1000cc)				Cord (D_max)				Esophagus (D_max)
Patient	∆Angle/∆Grid	MU	PTV (D_mean)	2°	4°	6°	10°	2°	4°	6°	10°	2°	4°	6°	10°	2°	4°	6°	10°
(a) G ₁ ^a
Proximal case	2 mm	1.00 (1777)^b	1.00 (50.32)^c	1.00 (0.21)	1.00	1.00	1.00	1.00 (2.99)	1.00	1.00	1.00	1.00 (18.03)	1.00	1.00	1.00	1.00 (16.01)	1.00	1.00	1.00
	3 mm	1.00	1.00	1.00	1.00	0.99	0.99	1.01	1.01	1.01	1.01	1.00	1.00	1.00	1.00	1.00	1.00	1.00	0.99
	4 mm	1.02	1.01	1.00	1.00	0.99	0.99	1.03	1.03	1.03	1.03	1.01	1.01	1.01	1.01	1.01	1.01	1.01	1.00
Intermediate case	2 mm	1.00 (1725)	1.00 (51.33)	1.00 (11.49)	1.00	1.00	1.02	1.00 (2.00)	1.01	1.00	0.97	1.00 (9.37)	1.00	1.01	1.02	1.00 (11.54)	1.00	1.00	1.03
	3 mm	1.00	1.00	1.00	1.00	1.00	1.02	1.01	1.01	1.01	0.98	1.00	1.00	1.01	1.02	1.00	1.00	1.00	1.03
	4 mm	1.01	1.01	1.01	1.01	1.01	1.02	1.03	1.03	1.03	1.00	1.00	1.00	1.01	1.02	1.01	1.01	1.01	1.03
Distant case	2 mm	1.00 (1767)	1.00 (51.09)	1.00 (27.57)	1.00	1.00	1.00	1.00 (3.61)	1.00	0.99	1.00	1.00 (8.14)	1.00	1.01	1.04	1.00 (10.23)	1.00	1.00	0.99
	3 mm	1.01	1.01	1.00	1.00	1.00	1.00	1.01	1.01	1.01	1.01	1.00	1.01	1.00	1.04	1.00	1.00	1.00	0.99
	4 mm	1.02	1.02	1.02	1.02	1.02	1.02	1.01	1.01	1.01	1.01	1.01	1.01	1.01	1.04	1.01	1.01	1.01	1.00
(b) G ₂ ^d
Proximal case	2 mm	1.00 (1542)	1.00 (51.25)	1.00 (0.34)	1.00	1.00	1.00	1.00 (9.38)	1.00	1.00	1.00	1.00 (25.31)	1.00	1.00	1.00	1.00 (20.57)	1.00	1.00	1.00
	3 mm	1.00	1.00	1.01	1.01	1.01	1.01	1.00	1.00	1.00	1.00	1.01	1.01	1.01	1.01	1.00	1.00	1.00	1.00
	4 mm	1.01	1.00	1.00	1.00	1.00	1.00	1.00	1.00	1.00	1.00	1.02	1.02	1.02	1.02	1.01	1.01	1.01	1.01
Intermediate case	2 mm	1.00 (1558)	1.00 (51.08)	1.00 (12.05)	1.00	1.00	1.01	1.00 (1.11)	1.00	1.00	1.00	1.00 (11.19)	1.00	1.00	1.02	1.00 (8.56)	1.00	1.01	1.05
	3 mm	1.00	1.00	1.01	1.00	1.00	1.02	1.01	1.01	1.01	1.01	1.00	1.00	1.00	1.02	1.00	1.00	1.01	1.05
	4 mm	1.01	1.01	1.01	1.01	1.01	1.02	1.03	1.03	1.03	1.02	1.02	1.01	1.01	1.02	1.01	1.01	1.02	1.05
Distant case	2 mm	1.00 (1658)	1.00 (50.68)	1.00 (31.91)	1.00	1.00	0.99	1.00 (1.09)	1.00	1.00	1.00	1.00 (5.54)	1.00	1.00	1.04	1.00 (6.66)	1.00	1.00	1.06
	3 mm	1.01	1.00	1.00	1.00	1.00	1.00	1.01	1.01	1.01	1.01	1.00	1.01	1.00	1.04	1.01	1.01	1.00	1.05
	4 mm	1.01	1.01	1.01	1.01	1.01	1.00	1.03	1.03	1.03	1.03	1.01	1.01	1.01	1.05	1.01	1.01	1.01	1.05
(c) G ₃ ^e
Proximal case	2 mm	1.00 (1625)	1.00 (52.00)	1.00 (20.55)	1.00	1.00	1.00	1.00 (6.75)	1.00	1.00	1.01	1.00 (24.96)	1.00	1.00	1.00	1.00 (14.41)	1.00	1.00	1.00
	3 mm	1.00	1.00	1.00	1.00	1.00	1.00	1.00	1.00	1.00	1.01	1.00	1.00	1.00	1.00	1.00	1.00	1.00	1.00
	4 mm	1.01	1.00	1.01	1.01	1.01	1.01	1.00	1.00	1.00	1.01	1.02	1.02	1.02	1.02	1.00	1.00	1.00	1.00
Intermediate case	2 mm	1.00 (1506)	1.00 (50.94)	1.00 (16.36)	1.00	1.00	1.01	1.00 (3.82)	1.00	1.00	1.00	1.00 (15.93)	1.00	1.00	1.01	1.00 (16.00)	1.00	1.00	1.01
	3 mm	1.00	1.00	1.00	1.00	1.01	1.01	1.01	1.01	1.01	1.01	1.00	1.00	1.00	1.01	1.00	1.00	1.00	1.00
	4 mm	1.01	1.01	1.01	1.01	1.01	1.02	1.01	1.01	1.01	1.01	1.01	1.01	1.01	1.01	1.00	1.00	1.00	1.00
Distant case	2 mm	1.00 (1566)	1.00 (52.07)	1.00 (0.70)	1.00	1.00	1.00	1.00 (6.23)	1.00	1.00	1.01	1.00 (12.61)	1.00	1.01	1.03	1.00 (18.42)	1.00	1.00	1.00
	3 mm	1.00	1.00	0.98	0.98	-0.98	0.98	1.00	1.00	1.00	1.01	1.00	1.00	1.01	1.03	1.00	1.00	1.00	1.00
	4 mm	1.01	1.00	0.98	0.98	-0.98	0.98	1.00	1.00	1.00	1.01	1.00	1.00	1.01	1.03	1.00	1.00	1.00	1.00

a) The patient group meeting the criteria of the PTV size, 3 cm ≤ d_equi < 3.5 cm. Each group includes three patients with different spinal cords distances (ds) from the isocenter as follows: proximal (ds < 6 cm), intermediate (6 cm ≤ ds ≤ 10 cm), and distant (10 cm ≤ ds). b) The reference MU value and c) the reference dose (Gy) were presented as absolute values in parentheses. d) The patient group meeting the criteria of the PTV size, 3.5 cm ≤ d_equi < 4.5 cm. e) The patient group meeting the criteria of the PTV size, 4.5 cm ≤ d_equi < 5.5 cm.

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