Dosimetric comparison of three different treatment techniques in extensive scalp lesion irradiation.

Abstract

This study compared lateral photon/electron plan (3DCRT), intensity modulated radiation therapy (IMRT) plan, and high dose rate (HDR) brachytherapy plan for total scalp irradiation. The techniques were planned on a patient with squamous cell carcinoma of the scalp for a prescribed dose of 60 Gy. Conformity indexes and dose volume histograms were used for the comparison. Clinical target volume coverage factors for 3DCRT, IMRT, and HDR were 0.976, 0.998, and 0.967, and Conformation Numbers were 0.532, 0.713, and 0.761, respectively. The dose gradient across the target was 59-136%, 91-129%, and 58-242% for 3DCRT, IMRT, and HDR techniques, respectively. The 3DCRT and IMRT techniques produced low optical structure doses. 3DCRT produced hotspots in the brain, while IMRT produced brain sparing. HDR produced the highest integral doses to the brain and optical structures. IMRT provided the best target dose homogeneity and coverage, and delivered clinically acceptable doses to normal structures. HDR produced the most conformal plan, but the total dose delivered is limited by doses to the brain and eyes. HDR is a clinically feasible alternative for less extensive lesions, lower prescription doses, and for patients who cannot lie on the treatment table.