Comparative treatment planning study for mediastinal Hodgkin’s lymphoma: impact on normal tissue dose using deep inspiration breath hold proton and photon therapy

Figures & data

Table 1. Patient and disease characteristics.

Age, median (range)	34 (15–71)
Gender
Female	10
Male	8
Stage
IIA	9 (7^a)
IIB	3 (3^a)
III	4 (4^a)
IV	1 (1^a)
Recurrence	1
Disease location
Mediastinum	3
Mediastinum + fscl	5
Mediastinum + fscl + neck	7
Mediastinum + fscl + neck + axilla	3

fscl: supraclavicular fossa.

^aUnfavorable disease.

Figure 2. The mean dose to the (a) lungs, (b) heart, (c) LAD, (d) right breast and (e) left breast for free breathing (FB) 3-dimensional conformal radiation therapy (3D-CRT), deep inspiration breath hold (DIBH) 3D-CRT, FB volumetric modulated arc therapy (VMAT), DIBH VMAT, FB intensity modulated proton therapy (IMPT) and DIBH IMPT. The values for each individual patient are shown in black and the median values for the whole patient cohort in red.

Table 2. Dosimetric parameters for free breathing (FB) and deep inspiration breath hold (DIBH) 3-dimensional conformal radiation therapy (3D-CRT), volumetric modulated arc therapy (VMAT) and intensity modulated proton therapy (IMPT).

Parameter	FB 3D-CRT	DIBH 3D-CRT	FB VMAT	DIBH VMAT	FB IMPT	DIBH IMPT	p value Friedman
V95%,CTV (%)	97.7 [90.9–100.0]^c,d,e,f	97.3 [91.1–99.9]^c,d,e,f	100.0 [100.0–100.0]^a,b,e,f	100.0 [100.0–100.0]^a,b,e,f	99.9 [97.8–100.0]^a,b,c,d,f	99.6 [98.4–100.0]^a,b,c,d,e	<.001
V95%,PTV (%)	91.9 [85.3–99.2]^c,d,e,f	90.2 [84.7–98.5]^c,d,e,f	98.0 [96.1–99.5]^a,b,e	98.0 [96.5–99.2]^a,b,e	99.4 [97.2–99.8]^a,b,c,d,f	98.8 [96.1–99.7]^a,b,e	<.001
HIPTV (%)	14.1 [8.8–18.9]^c,d,e,f	15.0 [9.2–17.6]^c,d,e,f	7.7 [5.5–9.9]^a,b,e	7.8 [5.7–10.0]^a,b,e	6.3 [4.3–9.5]^a,b,c,d,f	7.5 [4.2–11.3]^a,b,e	<.001
Dmean,Heart (Gy/Gy(RBE))	8.8 [0.5–22.9]^c,d,e,f	7.7 [0.5–27.3]^d,e,f	6.7 [0.4–18.3]^a,d,e,f	5.3 [0.5–20.6]^a,b,c,f	6.1 [0.0–17.6]^a,b,c	3.8 [0.1–20.9]^a,b,c,d	<.001
D2%,Heart (Gy/Gy(RBE))	29.2 [1.3–30.5]	29.1 [1.4–30.7]	29.8 [1.1–30.8]	29.5 [1.2–30.9]	30.0 [0.5–30.3]	29.6 [0.8–30.4]	.935
Dmean,LAD (Gy/Gy(RBE))	15.2 [0.7–30.4]^c,d,e,f	13.9 [0.7–26.9]^d,f	13.0 [0.7–30.1]^a,d,f	5.6 [0.7–22.7]^a,b,c,e	12.9 [0.1–29.8]^a,d	8.1 [0.1–23.1]^a,b,c	<.001
D2%,LAD (Gy/Gy(RBE))	28.3 [1.1–30.9]	28.5 [1.2–31.0]	29.9 [1.0–31.2]	22.7 [1.1–31.2]	30.3 [0.4–30.9]	26.6 [0.6–31.2]	.215
Dmean,lungs (Gy/Gy(RBE))	8.8 [4.2–18.8]^b,c,d,e,f	7.2 [3.8–15.8]^a,d,e,f	6.7 [4.0–14.2]^a,d,e,f	6.2 [3.6–14.1]^a,b,c,f	5.2 [1.9–13.8]^a,b,c,f	4.5 [1.8–12.2]^a,b,c,d,e	<.001
V20Gy,lungs (%)	21.3 [8.4–57.0]^b,c,d,e,f	16.8 [7.6–44.8]^a,c,d,e,f	10.3 [3.2–29.8]^a,b,d,e	8.9 [3.1–25.5]^a,b,c,e,f	12.7 [3.8–35.8]^a,b,c,d,f	10.9 [3.6–32.8]^a,b,d,e	<.001
V5Gy,lungs (%)	37.1 [16.3–76.1]^b,c,e,f	31.4 [15.1–70.9]^a,c,d,e,f	42.5 [22.7–83.5]^a,b,e,f	39.8 [20.0–91.1]^b,e,f	26.4 [9.7–66.4]^a,b,c,d,f	22.4 [9.1–58.0]^a,b,c,d,e	<.001
Dmean,left breast (Gy/Gy(RBE))^g	2.1 [0.3–10.0]^e,f	1.6 [0.5–5.6]^e,f	2.2 [0.5–7.0]^e,f	2.3 [0.5–5.3]^e,f	0.5 [0.0–2.6]^a,b,c,d	0.7 [0.0–2.1]^a,b,c,d	<.001
Dmean,right breast (Gy/Gy(RBE))^g	1.9 [0.4–8.5]^e,f	2.3 [0.5–9.9]^e,f	1.4 [0.4–5.3]^e,f	2.1 [0.4–5.1]^e,f	0.3 [0.0–3.0]^a,b,c,d	0.5 [0.0–4.2]^a,b,c,d	<.001
ID (Gy·kg/Gy(RBE)·kg)^h	80.6 [42.2–217.3]^c,e	85.8 [43.5–211.4]^d,f	79.8 [38.3–189.8]^a,e	84.9 [40.3–180.4]^b,f	42.2 [13.6–119.5]^a,c	44.9 [14.2–118.2]^b,d	<.001
CIPaddick	0.40 [0.35–0.56]^b,c,d,e,f	0.39 [0.31–0.59]^a,c,d,e,f	0.88 [0.85–0.90]^a,b,e,f	0.88 [0.84–0.91]^a,b,e,f	0.84 [0.74–0.87]^a,b,c,d,f	0.81 [0.71–0.86]^a,b,c,d,e	<.001

CTV: clinical target volume; PTV: planning target volume; HI: heterogeneity index; LAD: left anterior descending coronary artery; ID: integral dose; CI_Paddick: Paddick’s conformity index.

The data are presented as median value and range, with the results of the Friedman and pairwise Wilcoxon tests.

Statistically significant difference (p<.05) for the pairwise comparison of each treatment technique vs. alternatives: ^avs. FB 3D-CRT, ^bvs. DIBH 3D-CRT, ^cvs. FB VMAT, ^dvs. DIBH VMAT, ^evs. FB IMPT and ^fvs. DIBH IMPT.

^gFor the 10 female patients, ^hComparison only within the same breathing technique.