Dosimetric comparative study of 3-dimensional conformal radiation therapy (3D-CRT), volumetric-modulated arc therapy (V-MAT) and hybrid V-MAT (H-VMAT) in radiotherapy of cancer of the esophagus.

Divyashree, N; Narayanan, Geeta S; Banumathy, G; Sowmya, N

Background: Chemoradiation is an important treatment strategy for esophageal cancer. Attempts to intensify treatment have been hampered by unacceptable toxicity. Newer techniques are more conformal to target structures but increase lung dose. H-VMAT technique uses a combination of 3D-CRT and V-MAT to gain advantages of both plans. We have undertaken this study to explore the advantages of this new technique by comparing planning target volume (PTV) coverage and evaluate doses to Organs at Risk (OAR) like lungs, heart, and spinal cord in 3D-CRT, V-MAT, and H-VMAT. Methods: The study includes 30 esophageal cancer patients planned for concurrent chemo-radiation. Three plans were generated for each patient for a dose of 5040 cGy/28 fractions and compared using conformality index (CI), conformation number (CN), homogeneity index (HI), and dose received by 95% of volume (D95%). Results: CI and CN were significantly better in V-MAT but HI was comparable in all three techniques. D95% was statistically significant with H-VMAT. The spinal cord dose for H-VMAT was more than V-MAT but lesser than 3D-CRT. Dose to heart with H-VMAT was higher than V-MAT but lesser than 3D-CRT. Lung was significantly better with H-VMAT. Conclusion: The H-VMAT plans had better PTV coverage when compared with 3D-CRT and V-MAT plans. Though doses to the spinal cord and heart were high with H-VMAT, they were lesser than 3D-CRT plans. Lung sparing was significantly better with H-VMAT plans. Hence H-VMAT takes the advantage of better PTV coverage with V-MAT and better lung-sparing with 3D-CRT.

VOLUMETRIC-modulated arc therapy; ESOPHAGEAL cancer; SPINAL cord; ESOPHAGEAL tumors; RADIOTHERAPY

Indian Journal of Cancer, 2024, Vol 61, Issue 3, p490

0019-509X

Academic Journal

10.4103/ijc.IJC_201_20