Abstract
Background and PurposeTo investigate combining unmodulated electron beams with intensity-modulated radiation therapy to improve dose distributions for superficial head and neck cancers, and to compare mixed beam plans with helical tomotherapy.Materials and methodsMixed beam and helical tomotherapy dose plans were developed for two patients with parotid gland tumors and two patients with nasal cavity tumors. Mixed beam plans consisted of various weightings of a enface electron beam and IMRT, which was optimized after calculation of the electron dose to compensate for heterogeneity in the electron dose distribution within the target volume.ResultsHelical tomotherapy plans showed dose conformity and homogeneity in the target volume that was equal to or better than the mixed beam plans. Electron-only plans tended to show the lowest doses to normal tissues, but with markedly worse dose conformity and homogeneity than in the other plans. However, adding a 20% IMRT dose fraction (i.e., IMRT:electron weighting = 1:4) to the electron plan restored target conformity and homogeneity to values comparable to helical tomotherapy plans, while maintaining lower normal tissue dose.ConclusionsMixed beam treatments offer some dosimetric advantages over IMRT or helical tomotherapy for target depths that do not exceed the useful range of the electron beam. Adding a small IMRT component (e.g., IMRT:electron weighting = 1:4) to electron beam plans markedly improved target dose homogeneity and conformity for the cases examined in this study.
Highlights
Clinical radiation therapy techniques for superficial head and neck cancers have evolved dramatically over the past several decades
Previous works that have examined helical tomotherapy for superficial cancers generally conclude that it is capable of delivering dose distributions that are equivalent to or better than distributions delivered with fixedbeam IMRT [4,5] These results, augmented with institutional experience, have resulted in helical tomotherapy often being the treatment of choice for head and neck cancer in our clinic
Salguero et al [8] reported that modulated electron radiation therapy plans created with a photon multileaf collimator (MLC) showed comparable target volume dose homogeneity and significantly lower normal tissue dose compared with fixed-beam IMRT plans in four patients with superficial tumors head and neck tumors
Summary
Clinical radiation therapy techniques for superficial (i.e., located within approximately 5 cm of the patient surface) head and neck cancers have evolved dramatically over the past several decades. Salguero et al [8] reported that modulated electron radiation therapy plans created with a photon MLC showed comparable target volume dose homogeneity and significantly lower normal tissue dose compared with fixed-beam IMRT plans in four patients with superficial tumors head and neck tumors. Mu et al [14] compared various mixtures of electrons and IMRT for five deep-seated head and neck targets They reported that the mixed beam plans achieved adequate target and normal tissue dose with lower integral dose, and concluded that mixed beam plans could more readily meet planning goals if computerized optimization tools were available. To investigate combining unmodulated electron beams with intensity-modulated radiation therapy to improve dose distributions for superficial head and neck cancers, and to compare mixed beam plans with helical tomotherapy
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
