Evaluation of the dosimetric differences in esophagitis induced from radiotherapy of lung cancer patients using three different radiation techniques

Objective: To evaluate the dosimetric differences in esophagitis induced from radiotherapy using three radiation techniques of lung cancer patients: “Low-Modulated” Intensity Modulated Radiation Therapy (LM-IMRT), Stereotactic Body Radiation Therapy (SBRT) and Three Dimensional Conformal Radiation Therapy (3DCRT). Methods and Materials: In this retrospective study, treatment charts of 243 lung cancer patients treated with radiation therapy or combined with chemotherapy from year 2014 to 2017 at University of Mississippi Medical Center (UMMC) Radiation Oncology were reviewed. The dosimetric parameters such as mean esophagus dose (MED), Dmax, Dmin, V5, V10, V15, V20, V30, V40, V50, and V60from three treatment techniques are collected from the Pinnacle treatment planning system. One way ANOVA method was used to compare the dosimetric parameters, and Tukey multiple comparison tests were used for pairwise comparisons of the three treatment techniques. Results: There were significant difference indosimetric parameters between SBRT and LM-IMRT, and between SBRT and 3DCRT. There were no significant difference between LM-IMRT and 3DCRT for mean esophagus dose, V5, V10, V15, and V20, but there were significant difference for V30 and V40 for treatment prescription of 3DCRT at 37.5Gy in 15 fractions(or 30 Gy in 10 fractions) and LM-IMRT at 60Gy in 30 fractions (or 59.4 Gy in 33 fractions) daily. However, after rescaling the prescription of the 3DCRT to the same level of LM-IMRT at 60Gy in 30 fractions daily, dosimetric difference of esophagus between 3DCRT and LM-IMRT turned out to be statistically significant (p<0.05). Conclusions: The result of this study suggests that the Low-Modulated IMRT was superior compared to the 3DCRT technique in sparing the esophagus. Additionally, it is important to rescale the dose prescription to have apple to apple treatment technique comparison regarding the dosimetric parameters of esophagus from clinical application point of view. All treatment data for this research is from the single institute, therefore the variety of volumetric metrics of the esophagus from the different institute’s published data are avoided. Findings from this study can help clinicians in making decisions about which treatment technique to choose and how dosimetric parameters can be optimized to avoid potential complication in esophagus.