Cancer Res Treat.  2016 Jan;48(1):63-70. 10.4143/crt.2014.265.

Carotid-Sparing TomoHelical 3-Dimensional Conformal Radiotherapy for Early Glottic Cancer

• Hong CS
• Oh D
• Ju SG
• Ahn YC
• Noh JM
• Chung K
• Kim JS
• Suh TS

• KMID: 2152261
• DOI: http://doi.org/10.4143/crt.2014.265

Abstract

PURPOSE
The purpose of this study was to investigate the dosimetric benefits and treatment efficiency of carotid-sparing TomoHelical 3-dimensional conformal radiotherapy (TH-3DCRT) for early glottic cancer.
MATERIALS AND METHODS
Ten early-stage (T1N0M0) glottic squamous cell carcinoma patients were simulated, based on computed tomography scans. Two-field 3DCRT (2F-3DCRT), 3-field intensity-modulated radiation therapy (3F-IMRT), TomoHelical-IMRT (TH-IMRT), and TH-3DCRT plans were generated with a 67.5-Gy total prescription dose to the planning target volume (PTV) for each patient. In order to evaluate the plan quality, dosimetric characteristics were compared in terms of conformity index (CI) and homogeneity index (HI) for PTV, dose to the carotid arteries, and maximum dose to the spinal cord. Treatment planning and delivery times were compared to evaluate treatment efficiency.
RESULTS
The median CI was substantially better for the 3F-IMRT (0.65), TH-IMRT (0.64), and TH-3DCRT (0.63) plans, compared to the 2F-3DCRT plan (0.32). PTV HI was slightly better for TH-3DCRT and TH-IMRT (1.05) compared to 2F-3DCRT (1.06) and 3F-IMRT (1.09). TH-3DCRT, 3F-IMRT, and TH-IMRT showed an excellent carotid sparing capability compared to 2F-3DCRT (p < 0.05). For all plans, the maximum dose to the spinal cord was < 45 Gy. The median treatment planning times for 2F-3DCRT (5.85 minutes) and TH-3DCRT (7.10 minutes) were much lower than those for 3F-IMRT (45.48 minutes) and TH-IMRT (35.30 minutes). The delivery times for 2F-3DCRT (2.06 minutes) and 3F-IMRT (2.48 minutes) were slightly lower than those for TH-IMRT (2.90 minutes) and TH-3DCRT (2.86 minutes).
CONCLUSION
TH-3DCRT showed excellent carotid-sparing capability, while offering high efficiency and maintaining good PTV coverage.

Keyword

Early glottic cancer; Carotid sparing; TomoHelical three-dimensional conformal radiotherapy; Intensity-modulated radiotherapy

MeSH Terms

Carcinoma, Squamous Cell
Carotid Arteries
Humans
Prescriptions
Radiotherapy, Conformal*
Radiotherapy, Intensity-Modulated
Spinal Cord

Figure

• 

  Fig. 1. An axial view of isodose distributions at the target center for each of the four treatment plans and a single representative patient. (A) Two-field 3-dimensional conformal radiotherapy (2F-3DCRT). (B) Three-field intensity-modulated radiation therapy. (C) TomoHelical IMRT. (D) TomoHelical 3DCRT. Under 2F-3DCRT, the high-dose region that received the prescription dose was widely distributed over the carotid artery. Under the other three plans, the high-dose region did not include the carotid artery.

• 

  Fig. 2. This figure shows the mean dose-volume histogram (10 patients) for the carotid artery, including results for each of the four treatment plans that were investigated. In our treatment-planning simulations, the normalized volume of the carotid artery that received in excess of 30 Gy was the lowest using TomoHelical intensity-modulated radiation therapy (TH-IMRT), the second-lowest using TomoHelical 3-dimensional conformal radiotherapy (TH-3DCRT), the third-lowest using 3-field IMRT (3F-IMRT), and the highest using 2-field 3DCRT (2F-3DCRT).

Reference

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