Comparison of field-in-field (FiF), intensity modulated radiation therapy (IMRT) and volumetric arc radiation therapy (VMAT) treatment techniques for post-mastectomy radiotherapy

Purpose: To investigate the feasibility of Field-in-Field (FiF), Intensity Modulated Radiotherapy (IMRT) and Volumetric Modulated Arc Therapy (VMAT) for Postmastectomy Radiotherapy (PMRT) and compare tangential VMAT treatment plans to IMRT and FiF plans. Methods: FiF, IMRT and tVMAT treatment plans were created for seventeen PMRT patients previously treated at our clinic. XIO treatment planning systems was used for FiF treatment plans and MONACO Planning systems was used for IMRT, tVMAT treatment plans. Planning target volumes (PTV) included the chest wall. Lenf nodes, axilla, supra clavicular fossa, ipsilateral, contralateral and total lungs, heart and contralateral breast doses was evaluated. The following metrics were used to compare treatment plans for each patient. FiF plans were generated tangential field and clavicular and axilla field, IMRT plans consisting of 6 beams of about tangential beam, ±150 adding beam and a VMAT plans consisting of 2 small tangential arc segments of about 600. Results: All treatment methods clinically can be accepted PMRT plans. As a results of statistical analyzes, all of data have the normal dispersion. While all techniques are occurred acceptable results for target volumes, tVMAT and IMRT plans showed better for critical volumes to compared the FiF plans. tVMAT and IMRT plans showed a 31.0% and 28.5% decrease in V20Gy in the left lung to compared the FiF plans (p<0.05). tVMAT and IMRT plans showed a 32.4% and 33.8% decrease in mean doses of heart compared to FiF plans. Heart doses evaluated in terms of the plans shows significant differences between IMRT and FIF plans statistically. However, tVMAT plans have not been differences compared with FiF and IMRT. When examined the maximum doses of contralateral breast are differences between FiF and tVMAT plans (p<0.05). Conclusion: FiF, IMRT and tVMAT provide acceptable treatment plans for target volumes and these plans can be delivered in clinical procedures. However Our study showed that tVMAT technique gives better results according to both IMRT and FiF techniques when the ciritical volumes are concerned particularly for heart and lung doses. So that, the parameters like anatomical structure, immobilization and physical specification of the patients should also be taken in consideration to perform these planning techniquies.