Bone marrow-sparing intensity-modulated radiation therapy for Stage I seminoma

Figures & data

Table I. Target volume and organs at risk dose constraints used in bone marrow-sparing intensity-modulated radiotherapy treatment planning.

Structure	Constraints	Volume (%)	Dose in Gy (%)
CTV	Upper	0	22 (110%)
	Dmean	100	20 (100%)
PTV	Upper	1	21.4 (107%)
	Lower	100	19 (95%)
ABM	Dmean	100	< 7.5
Combined kidneys	Upper	1	20 (100%)
	Upper	20	15 (75%)
	Upper	33	10 (50%)
	Dmean	100	< 6.9
Bowel	Upper	50	10 (50%)
Stomach	Upper	50	5 (25%)
Pancreas	Upper	30	20 (100%)
	Upper	50	15 (75%)
Liver	Upper	33	10 (50%)
Spinal cord	No dose constraint

CTV, clinical target volume; PTV, planning target volume; ABM, active bone marrow.

Figure 1. Patient with Stage I testicular seminoma: color wash bone-marrow-sparing intensity-modulated radiotherapy (BMS-IMRT) (a, c) and computed tomography-based traditional radiotherapy (CT-tRT) (b, d) isodose distributions (95% isodose line) on axial (a, b) and sagittal (c, d) views.

Figure 2. Mean dose-volume histograms for planning target volume (PTV) and organs at risk (OARs) for bone-marrow-sparing intensity-modulated radiotherapy (BMS-IMRT) and computed tomography-based traditional radiotherapy (CT-tRT).

Table II. Comparison of dosimetric parameters for clinical target volume (CTV) and planning target volume (PTV). Results in mean ± SD (n = 10).

Variable	CT-tRT	BMS-IMRT	p-value
CTV Dmean (Gy)	20.5 ± 0.1	20.5 ± 0.07	0.445
CTV Dmin (%)	98.5 ± 0.4	98.9 ± 0.6	0.139
PTV Dmean (Gy)	20.3 ± 0.1	20.2 ± 0.05	0.093
PTV Dmax (%)	105.8 ± 0.9	105.6 ± 0.9	0.646
PTV D50% (Gy)	20.4 ± 0.1	20.4 ± 0.08	0.859
PTV D95% (Gy)	19.7 ± 0.06	19.5 ± 0.06	0.005*
PTV V95% (%)	100	99.7 ± 0.2	0.011*
PTV V93% (%)	100	100	–
Monitor units/fraction (n)	236 ± 7	1180 ± 222	0.005*

CT-tRT, Computed tomography-based traditional radiotherapy; BMS-IMRT, bone marrow-sparing intensity-modulated radiotherapy; D_n%, minimal dose delivered to the percentage of volume of the target volume; V_n%, volume receiving at least n% of the prescribed dose.

*Statistically significant.

Table III. Comparison of dosimetric parameters for organs at risk and non-target tissues. Results in mean ± SD (n = 10).

Variable	CT-tRT	BMS-IMRT	p-value
Active bone marrow
Dmean (Gy)	13.1 ± 1.3	7.9 ± 0.5	0.005*
D50% (Gy)	19.7 ± 1.2	7.1 ± 0.9	0.005*
V100% (%)	53.4 ± 5.9	1.7 ± 0.8	0.005*
V75% (%)	59.0 ± 5.9	16.7 ± 1.4	0.005*
V50% (%)	61.2 ± 5.9	34.9 ± 3.2	0.005*
Combined kidneys
Dmean (Gy)	6.8 ± 1.5	8.0 ± 0.8	0.007*
D50% (Gy)	2.2 ± 1.3	7.4 ± 0.9	0.005*
V100% (%)	8.6 ± 4.0	0.9 ± 0.4	0.005*
V75% (%)	25.1 ± 6.8	8.8 ± 2.5	0.005*
V50% (%)	30.4 ± 8.0	23.9 ± 7.1	0.038*
Bowel
Dmean (Gy)	6.2 ± 1.0	8.1 ± 0.7	0.005*
D50% (Gy)	0.9 ± 0.3	8 ± 0.4	0.005*
V100% (%)	17.2 ± 4.6	1.5 ± 0.8	0.005*
V75% (%)	24.7 ± 4.6	7.9 ± 2.5	0.005*
V50% (%)	27.3 ± 4.9	26.6 ± 5.6	0.959
Stomach
Dmean (Gy)	7.6 ± 3.8	5.0 ± 2.3	0.011*
D50% (Gy)	5.0 ± 7.2	3.4 ± 2.6	0.878
V100% (%)	22.4 ± 13.0	0.4 ± 1.0	0.005*
V75% (%)	30.8 ± 17.7	3.1 ± 3.0	0.005*
V50% (%)	33.8 ± 19.2	14.9 ± 8.3	0.005*
Pancreas
Dmean (Gy)	12.5 ± 3.6	12.2 ± 1.7	0.799
D50% (Gy)	16.3 ± 5.7	10.2 ± 3.7	0.017*
V100% (%)	40.2 ± 16.4	3.1 ± 3.7	0.005*
V75% (%)	61.5 ± 17.6	25.6 ± 14.4	0.005*
V50% (%)	65.3 ± 16.5	62.8 ± 14.2	0.575
Liver
Dmean (Gy)	2.8 ± 1.6	3.8 ± 1.3	0.008*
D50% (Gy)	0.4 ± 0.1	2.3 ± 1.6	0.005*
V100% (%)	3.2 ± 3.5	0.1 ± 0.3	0.018*
V75% (%)	8.0 ± 6.0	1.9 ± 1.3	0.008*
V50% (%)	10.0 ± 6.9	8.4 ± 4.7	0.173
Spinal Cord
Dmax (%)	107.4 ± 1.7	65.7 ± 5.0	0.005*
Dmean (Gy)	19.8 ± 0.5	8.0 ± 0.8	0.005*
D50% (Gy)	21.0 ± 0.3	8.5 ± 0.7	0.005*
Non-target tissues
DoseInt	1.02 ± 0.18	0.99 ± 0.20	0.028*

CT-tRT, computed tomography-based traditional radiotherapy; BMS-IMRT, bone marrow-sparing intensity-modulated radiotherapy; D_n%, minimal dose delivered to the percentage of volume of the target volume; V_n%, volume receiving at least n% of the prescribed dose; Dose Int, integral dose (Gy*cm³*10⁵).

*Statistically significant