The Feasibility of Hybrid IMRT treatment planning for Left sided Chest wall irradiation: A Comparative Treatment Planning Study

Abstract

Introduction: Due to the limited target volume and irregular body surface, irradiating the chest wall (CW) and lymphatic nodes is more challenging. IMRT and VMAT (volumetric modulated arc therapy) are two treatment delivery techniques that help to improve dose coverage and homogeneity while reducing irradiation to the heart and ipsilateral (I/L) lung. The use of a hybrid treatment planning approach for the ca-breast will impact the treatment plan. The hybrid planning system must be reviewed and compared to alternative treatment options for ca-breast cancer. Material and Methods: For 10 patients undergoing left-sided breast chest wall irradiation, the 3 distinct planning techniques (FiF [Field-in-field], IMRT, and Hybrid IMRT) were evaluated. A prescription dose of 40 Gy in 15 fractions was used for the planned target volume (PTV). To compare plans, dose-volume histograms (DVHs) were assessed for PTV and organs at risk. Results: D95% of PTV was 37.10 ± 0.48 Gy in FiF, but considerably raised to 39.32 ± 0.34 Gy and 38.39 ± 0.29 Gy in IMRT (p=0.01) and Hybrid IMRT (p=0.01).When compared to IMRT (0.981 ± 0.014) and Hybrid IMRT (0.970 ± 0.013) FiF plans have the lowest CI value of 0.931 ± 0.026. IMRT plans (0.087 ± 0.021) were found to be more homogeneous than other 2 planning techniques (0.111 ± 0.013 [FiF, p=0.016], 0.107 ± 0.021[hybrid IMRT, p=0.056]). Conclusion: Hybrid IMRT treatment plans for the ca-breast are recommended because they provide superior and similar PTV dose coverage and OAR sparing compared to FiF and IMRT plans. Hybrid IMRT plans feature lower MU and BOT, as well as a smaller low dose volume in comparison to IMRT.

Keywords

• field in field
• intensity modulated radiotherapy
• hybrid
• chest wall
• monitor unit