Document Type : Original Paper
Authors
1
Department of Physics, Tilak Dhari P. G. College, Jaunpur, (U.P.) - 222002, INDIA and Department of Radiation Oncology, Lecturer(Physicist), Uttar Pradesh University of Medical Sciences, Saifai etawah-UP 206130 India
2
Department of Physics, Tilak Dhari P. G. College, Jaunpur, (U.P.) - 222002, INDIA
3
Department of Radiation Oncology, Uttar Pradesh University of Medical Sciences, Saifai, Etawah (U.P.) - 206130, INDIA
4
Department of Radiation Oncology, Dr. Ram Manohar Lohia Institute of Medical Sciences, Vibhuti Khand Gomti Nagar, Lucknow -226010
5
Department of Radiation Oncology, Dr. Ram Manohar Lohia Institute of Medical Sciences, Vibhuti Khand Gomti Nagar, Lucknow -226010 India
Abstract
Introduction: With the introduction of Intensity Modulated Radiotherapy (IMRT) approach, better dosimetry results and patient outcomes has been attained for various anatomical sites. In present study, a comparative dosimetric evaluation of Volumetric-Modulated Arc Therapy (VMAT) versus two techniques of IMRT i.e. Dynamic IMRT (d-IMRT) and step & shoot IMRT (ss-IMRT) was done for thoracic esophageal cancer.
Materials and Methods: VMAT, ss-IMRT, and d-IMRT plans were generated on the Computed Tomography Simulator data sets of 13 Patients of thoracic esophageal carcinoma who had been treated earlier. The prescription dose for each patient was 50.4 Gy in 28 fractions. All the plans were optimized to achieve greater or equal to 95% of the prescribed dose to the Planning Target Volume (PTV). Dose to PTV and organ at risk (OAR) were compared with the help of Dose Volume Histogram (DVH).
Results: VMAT and d-IMRT plans were nearly equivalent for PTV coverage, homogeneity index (HI), and uniformity index (UI) (p> 0.05). However, VMAT and d-IMRT plans had superior PTV coverage, HI and UI, (p < 0.01) than ss-IMRT. The Dmean and D95 differed significantly among the three techniques of VMAT, ss-IMRT, and d-IMRT (p< 0.006). For PTV, the Dmean, D98, and D95 values in ss-IMRT were significantly less than VMAT and d-IMRT (p< 0.05).
Conclusion: VMAT and d-IMRT results in homogeneous dose distribution and may be preferred for treating thoracic esophageal carcinoma as compared to ss-IMRT. VMAT may be a better option with equivalent or superior dose distribution, uniformity and homogeneity.
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