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Breast size and dose to cardiac substructures in adjuvant three-dimensional conformal radiotherapy compared to tangential intensity modulated radiotherapy

Ivica Ratosa
Ivica Ratosa
, 
Aljasa Jenko
Aljasa Jenko
, 
Zeljko Sljivic
Zeljko Sljivic
, 
Maja Pirnat
Maja Pirnat
 and 
Irena Oblak
Irena Oblak
   | Sep 29, 2020
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Article Category: Research Article
Published Online: Sep 29, 2020
Page range: 470 - 479
Received: Mar 18, 2020
Accepted: May 10, 2020
DOI: https://doi.org/10.2478/raon-2020-0050
© 2020 Ivica Ratosa, Aljasa Jenko, Zeljko Sljivic, Maja Pirnat, Irena Oblak, published by Sciendo
This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

Figure 1

Mean whole heart dose and number of plans within each CTV groups, concerning optimal mean dose value.3D-CRT = three-dimensional conformal radiotherapy; CTV = clinical target volume; Gy = Gray; t-IMRT = tangential intensity modulated radiation therapy
Mean whole heart dose and number of plans within each CTV groups, concerning optimal mean dose value.3D-CRT = three-dimensional conformal radiotherapy; CTV = clinical target volume; Gy = Gray; t-IMRT = tangential intensity modulated radiation therapy

Figure 2

Bull’s eye diagrams of the left ventricle and segment models of the coronary arteries with reported median Dmean distributions in three-dimensional conformal radiotherapy plans, divided in groups according to clinical target volume size. Contouring segments of left ventricle consisted of anterior (segments 1 and 7), apical (segments 13–17), inferior (segments 4 and 10), lateral (segments 5, 6, 11, 12) and septal regions (segments 2, 3, 8, 9).CTV = clinical target volume; Gy = Gray; LADCA = left anterior descending artery; LCX = left circumflex artery; LMCA = left main coronary artery; RCA = right coronary artery
Bull’s eye diagrams of the left ventricle and segment models of the coronary arteries with reported median Dmean distributions in three-dimensional conformal radiotherapy plans, divided in groups according to clinical target volume size. Contouring segments of left ventricle consisted of anterior (segments 1 and 7), apical (segments 13–17), inferior (segments 4 and 10), lateral (segments 5, 6, 11, 12) and septal regions (segments 2, 3, 8, 9).CTV = clinical target volume; Gy = Gray; LADCA = left anterior descending artery; LCX = left circumflex artery; LMCA = left main coronary artery; RCA = right coronary artery

Target volumes’ and organs at risk’s metrics

Target volume/ Organ at riskThe whole group N = 60Small CTV N = 22Medium CTV N = 21Large CTV N = 17p value
CTV [cm3]800.6 (124.8–2970.9)425.7 (124.8–545.5)867.0 (652.1–1295.1)1586.8 (1348.9–2970.9)0.021
PTVeval [cm3]990.7 (233.5–3336.1)583.0 (233.5–711.1)1035.9 (834.3–1576.5)1874.3 (1605.8–3336.1)< 0.005
PTV [cm3]1163.3 (340.1–3792.2)730.7 (340.1–856.6)1212.3 (985.1–1805)2134.8 (1826.4–3792.2)< 0.005
CWS [cm]23.1 (17.9–33.2)19.5 (17.9–23.2)24.0 (19.9–28.5)27.5 (22.9–33.2)< 0.005
4th arch metrics [cm]4.4 (0–11.6)1.6 (0–9.6)5.5 (0–11.6)7.1 (0–10.7)0.008
Heart [cm3]677.7 (432.9–1192.7)625.2 (432.9–912.8)671.1 (563.5–872.4)817.9 (620.1–1192.7)< 0.005
Left Ventricle [cm3]173.8 (116–277.4)161.3 (116–251.7)173.8 (120.8–229.8)188.7 (147.4–277.4)0.018
Left Lung [cm3]1245.1 (809.3–2127.9)1458.9 (824.5–2127.9)1123.8 (944.2–1619.2)1230.6 (809.3–1541.7)0.003
Right Lung [cm3]1563.4 (855–2560.1)1721.9 (992.9–2560.1)1466.4 (855.1–1838.2)1493.2 (1089.6–1925.6)0.002
Lungs [cm3]2879.7 (1504.6–4789.2)3241.3 (1877.5–4789.2)2634.4 (1504.6–3513.6)2799.8 (1960.2–3479.2)0.001

Radiotherapy technique and selected dose-volume parameters for the whole heart and selected cardiac substructures

Parameter3D-CRTt-IMRTp value*
MWHD [Gy]1.90 (0.61–4.14)2.13 (1.06–4.4)< 0.005
LV-Dmean [Gy]2.98 (0.78–8.03)3.22 (1.31–7.25)< 0.005
LV-V5 Gy [%]8.67 (0–26.3)9.21 (0–26.02)0.455
LV-V23 Gy [%]2.46 (0–14.32)1.86 (0–10.58)0.003
LV anterior-Dmean [Gy]5.00 (1.27–20.17)5.42 (1.94–19.18)< 0.005
LV apical-Dmean [Gy]8.97 (1.22–24.89)8.47 (1.64–22.16)< 0.005
LADCA-Dmean [Gy]8.20 (1.23–27.92)8.39 (1.8–27.62)< 0.005
LADCA-V30 Gy [%]5.39 (0–66.34)2.01 (0–84.20)< 0.005
LADCA-V40 Gy [%]0 (0–37.8)0 (0–43.09)< 0.005
LADCA-prox-Dmean [Gy]2.17 (0.62–8.68)2.66 (1.22–12.43)< 0.005
LADCA-mid-Dmean [Gy]9.63 (1.67–40.07)11.05 (2.26–39.63)0.956
LADCA-dist-Dmean [Gy]13.73 (1.44–41.11)15.93 (2.03–3.89)0.132

Breast size and selected dose-volume parameters for the whole heart and cardiac substructures

Small CTVMedium CTVLarge CTV
Parameterp value
3D-CRTt-IMRT3D-CRTt-IMRT3D-CRTt-IMRT
MWHD [Gy]1.29 (0.61–3.75)1.99 (1.06–3.98)2.05 (1.06–3.84)2.11 (1.62–3.54)2.26 (1.04–4.14)2.72 (1.46–4.4)< 0.005*; 0.047†
Heart-V5 Gy [%]2.56 (0.02–10.84)3.77 (0.1–11.01)4.99 (0.59–10.87)4.34 (1.19–9.58)5.29 (0–12.81)6.19 (0.04–12.83)0.043*
Heart-V10 Gy [%]1.28 (0–7.91)2.01 (0–7.59)2.71 (0.01–7.73)2.24 (0.12–68.14)3.09 (0–8.24)3.17 (0–8.54)NS
Heart-V17 Gy [%]0.76 (0–6.61)1.22 (0–6.08)2.03 (0–6.52)1.36 (0–4.79)2.37 (0–6.92)3.36 (0–6.42)NS
Heart-V20 Gy [%]0.62 (0–6.22)1 (0–5.63)1.83 (0–6.16)1.17 (0–4.38)2.15 (0–6.51)2.01 (0–5.81)NS
Heart-V35 Gy [%]0.15 (0–4.12)0.2 (0–3.4)0.93 (0–4.15)0.31 (0–2.3)1.06 (0–4.32)0.63 (0–2.91)NS
Heart-V40 Gy [%]0.02 (0–1.41)0.01 (0–1.65)0.24 (0–1.45)0.03 (0–0.42)0.03 (0–1.93)0.04 (0–1.69)NS
LV-Dmean [Gy]2.3 (0.7–5.7)2.9 (1.31–5.84)3.2 (1.1–6.9)3.15 (1.78–5.97)3.5 (1.3–8.0)3.92 (1.83–7.25)0.019*
LV-V5 Gy [%]6.8 (0–17.4)8.27 (0–17.39)9.7 (0–22.0)8.47 (0.46–19.87)10.8 (0–26.3)12 (0–26.02)0.052*
LV-V23 Gy [%]1.4 (0–9.5)1.73 (0–8.47)2.8 (0–12.0)1.81 (0–8.18)3.3 (0–14.3)3.1 (0–10.58)NS
LV anterior-Dmean [Gy]3.6 (1.2–12.8)4.86 (1.94–12.35)6.8 (2.0–15.9)5.71 (2.69–14.48)6.8 (1.9–20.1)6.94 (2.58–19.18)0.017*
LV lateral-Dmean [Gy]1.6 (0.7–2.8)2.16 (1.18–3.38)1.8 (0.9–6.3)2.24 (1.55–5.12)2.5 (1.2–8.7)2.98 (1.73–7.59)< < 0.0010.001*, †
LV inferior-Dmean [Gy]0.5 (0.3–3.3)0.96 (0.77–1.17)0.6 (0.5–0.9)1.07 (0.9–1.32)0.8 (0.6–2.0)1.33 (0.96–1.98)< < 0.0050.005*, †
LV septal-Dmean [Gy]1.2 (0.4–3.4)1.8 (1.01–3.71)1.6 (1.1–3.4)2.19 (1.77–3.74)1.9 (1.2–3.9)2.56 (1.72–4.46)< < 0.0050.005*, †
LV apical-Dmean [Gy]6.9 (1.2–19.6)8.54 (1.64–19.79)9.0 (1.7–21.9)8.42 (2.46–19.68)9.5 (1.2–24.8)8.91 (1.76–22.16)NS
LADCA-Dmean [Gy]5.2 (1.2–27.9)6.84 (1.8–27.62)13.8 (2.6–25.2)10.76 (3.01–20.73)11.1 (2.2–21.2)8.24 (2.84–21.22)NS
LADCA-V30 Gy [%]0.2 (0–66.3)0.36 (0–63.48)17.8 (0–59.0)7.39 (0–84.2)8.9 (0–43.3)2.13 (0–46.34)NS
LADCA-V40 Gy [%]0 (0–37.8)0 (0–43.09)0.5 (0–32.9)0 (0–3.22)0 (0–19.2)0 (0–7.26)NS
LADCA-prox-Dmean [Gy]1.6 (0.6–8.6)2.22 (1.22–7.95)2.9 (0.6–7.2)2.96 (1.96–5.19)2.5 (1.4–7.2)2.84 (2.07–12.43)< 0.001*, 0.002†
LADCA-mid-Dmean [Gy]7.9 (1.6–40.0)9.12 (2.26–39.63)17.9 (2.0–38.7)13.81 (4.22–30.95)10.4 (2.5–29.8)11.14 (3.23–36.01)NS
LADCA-dist-Dmean [Gy]5.5 (1.4–41.1)8.58 (2.03–40.65)26.9 (3.5–39.4)17.46 (3.98–35.39)14.0 (2.4–39.7)16.32 (2.87–34.95)NS

Target goals used in the planning process

StructureTarget goals
PTVD2%< 108%
PTVevalV95%> 95%
Whole Body ContourGlobal Dmax < V110%
Dmean < 3.2 Gy
HeartV17 Gy < 10%
V35 Gy < 5%
Dmean < 10 Gy
Ipsilateral LungV17 Gy < 25%
V26 Gy < 20%
Bilateral lungDmean < 3.2 Gy

Target volume dosimetric metrics

Target volume3D-CRTt-IMRTp value
PTVeval D98% [Gy]40.6 (39.8–41.4)40.3 (38.7–41.6)0.002
PTVeval D2% [Gy]44.7 (44.4–45.5)43.8 (43.8–47.1)NS
PTVeval D50% [Gy]43.3 (42.7–43.7)42.9 (42.2–43.9)< 0.005
PTVeval V95% [%]98.1 (95.3–99.6)96.8 (79.9–99.9)0.001
PTVeval V105% [%]1.3 (0.1–10.3)4.3 (0.01–85.9)< 0.005
PTVeval V105% [cm3]11.7 (0.08–656.7)5.4 (0.06–68.0)0.014
PTVeval V107% [%]0 (0–1.4)0.1 (0–9.6)< 0.005
PTVeval V107% [cm3]0 (0–321.4)0 (0–7.2)NS
PTVeval V110% [%]0 (0–0)0 (0–0)NS
Dmax [Gy]45.7 (45.1–46.9)46.9 (45.3–51)< 0.005

Target volume dosimetric metrics and CTV size

Target volumeSmall CTVMedium CTVLarge CTVp value (S vs. M vs. L)
3D-CRT PTVeval V95% [%]97.7 (95.3–99.6)98.3 (96.2–99.5)98.8 (97.5–99.4)0.022 (S vs. M, S vs. L)
t-IMRT PTVeval V95% [%]97.9 (96.3–99.2)97.3 (95.3–99.0)96.8 (79.9–99.9)NS
p value (3D-CRT vs. T-IMRT)NSp = 0.003p = 0.013
3D-CRT PTVeval V105% [cm3]8.1 (0.5–17.5)12.5 (0.08–91.3)87.3 (9.5–656.6)< 0.005 (S vs. M, S vs. L, M vs. L)
t-IMRT PTVeval V105% [cm3]7.4 (0.1–61.5)5.9 (0.09–54)4.2 (0.06–68.2)NS
p value (3D-CRT vs. T-IMRT)NSNSp = 0.012
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