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Comparison of Carotid Artery Dose in Early-Stage Glottic Cancer Treated with 3D-Conformal, Helical-IMRT and VMAT

B Pires
B Pires
, 
D Rothwell
D Rothwell
, 
I Guimarães
I Guimarães
, 
J Sousa
J Sousa
, 
R Magalhães
R Magalhães
, 
T Serra
T Serra
, 
L Khouri
L Khouri
 and 
P Alves
P Alves
   | Nov 13, 2023
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Article Category: Research Article
Published Online: Nov 13, 2023
Page range: 23 - 30
Received: Jun 19, 2023
Accepted: Oct 07, 2023
DOI: https://doi.org/10.2478/fco-2023-0009
Keywords
© 2023 B Pires et al., published by Sciendo
This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

Figure 1:

Dose distribution with prescribed isodose curves (50% in dark blue, 80% in light blue, and 95% in orange) for four patients with T1–2 left glottic squamous cell cancer, who underwent radical radiotherapy at a dose of 63–65.25 Gy in 28–29 fractions over 5.6–5.8 weeks. The red volumes represent the clinical target volume (CTV) and the planning target volume (PTV). Axial slices of representative cases were planned using (A) 3D-conformal radiotherapy with opposed lateral fields, (B) 3D-conformal radiotherapy with oblique beams, (C) helical tomotherapy-intensity-modulated radiotherapy, and (D) volumetric modulated arc therapy.
Dose distribution with prescribed isodose curves (50% in dark blue, 80% in light blue, and 95% in orange) for four patients with T1–2 left glottic squamous cell cancer, who underwent radical radiotherapy at a dose of 63–65.25 Gy in 28–29 fractions over 5.6–5.8 weeks. The red volumes represent the clinical target volume (CTV) and the planning target volume (PTV). Axial slices of representative cases were planned using (A) 3D-conformal radiotherapy with opposed lateral fields, (B) 3D-conformal radiotherapy with oblique beams, (C) helical tomotherapy-intensity-modulated radiotherapy, and (D) volumetric modulated arc therapy.

Figure 2:

Verification of differences in mean and maximum doses (Gy) to carotid arteries among treatment techniques using the nonparametric Kruskal–Wallis test.
Verification of differences in mean and maximum doses (Gy) to carotid arteries among treatment techniques using the nonparametric Kruskal–Wallis test.

Summary of the patients’ demographics and disease and treatment characteristics for the three different radiotherapy techniques utilized in this study.

Characteristics Treatment technique Significance
3D-CRT (n = 14) (%) HT-IMRT (n = 8) (%) VMAT (n = 6) (%)
Sex p = 0.7
Female 1 (7.1) 1 (12.5) 0 (0.0)
Male 13 (92.9) 7 (87.5) 6 (100.0)
Age at diagnosis p = 0.1
<60 years 3 (21.4) 1 (12.5) 4 (66.7)
≥60 years 11 (78.6) 7 (87.5) 2 (33.3)
Performance status p = 0.1
ECOG 0 14 (100.0) 6 (75.0) 6 (100.0)
ECOG 1 0 (0.0) 2 (25.0) 0 (0.0)
Prognostic stage groups p = 0.3
Stage 0 2 (14.3) 0 (0.0) 0 (0.0)
Stage I 11 (78.6) 5 (63.5) 4 (66.7)
Stage II 1 (7.1) 3 (37.5) 2 (33.3)
Tumor location/target treatment volume p = 0.4
Both vocal cords 4 (28.6) 3 (37.5) 1 (16.7)
Right vocal cord 4 (28.6) 2 (25.0) 0 (0.0)
Left vocal cord 6 (42.9) 3 (37.5) 5 (83.3)
Mean ± SD total radiation dose (Gy) 64.9 ± 1.7 62.4 ± 5.4 64.4 ± 1.5 p = 0.2
Mean ± SD no. of fractions received 31.2 ± 2.5 29.3 ± 4.3 29.8 ± 2.5 p = 0.3
Mean ± SD dose per fraction (Gy) 2.1 ± 0.1 2.2 ± 0.2 2.2 ± 0.1 p = 0.4

Comparison of dosimetric characteristics among the three treatment techniques.

Parameter Treatment technique Significance
3D-CRT (n = 14) HT-IMRT (n = 8) VMAT (n = 6)
Right carotid artery
Mean dose, Gy (range) 30.9 (15.8–47.4) 27.6 (23.2–34.6) 16.6 (13.0–47.4) p = 0.01
Dmax, Gy (range) 51.7 (24.6–68.9) 49.9 (32.2–62.4) 31.9 (26.1–48.2) p = 0.02
Mean volume delineated, ml (range) 5.0 (3.6–6.4) 3.9 (2.8–5.8) 4.2 (2.6–6.5) p = 0.1
Left carotid artery
Mean dose, Gy (range) 31.0 (20.1–43.7) 28.2 (19.0–43.2) 23.4 (15.5–30.1) p = 0.1
Dmax, Gy (range) 54.0 (30.4–67.1) 49.7 (30.4–66.2) 48.4 (31.5–60.9) p = 0.6
Mean volume delineated, ml (range) 4.7 (3.1–6.2) 4.0 (3.0–5.8) 4.0 (2.5–5.6) p = 0.3
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