Open AccessVolumetric modulated arc therapy versus step‐and‐shoot intensity modulated radiation therapy in the treatment of large nerve perineural spread to the skull base: a comparative dosimetric planning study
Author(s) -
Gorayski Peter,
Fitzgerald Rhys,
Barry Tamara,
Burmeister Elizabeth,
Foote Matthew
Publication year - 2014
Publication title -
journal of medical radiation sciences
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.484
H-Index - 18
eISSN - 2051-3909
pISSN - 2051-3895
DOI - 10.1002/jmrs.45
Subject(s) - nuclear medicine , medicine , radiation therapy , radiation treatment planning , base of skull , skull , radiology , surgery
Abstract Introduction Cutaneous squamous cell carcinoma with large nerve perineural ( LNPN ) infiltration of the base of skull is a radiotherapeutic challenge given the complex target volumes to nearby organs at risk ( OAR ). A comparative planning study was undertaken to evaluate dosimetric differences between volumetric modulated arc therapy ( VMAT ) versus intensity modulated radiation therapy ( IMRT ) in the treatment of LNPN . Methods Five consecutive patients previously treated with IMRT for LNPN were selected. VMAT plans were generated for each case using the same planning target volumes ( PTV ), dose prescriptions and OAR constraints as IMRT . Comparative parameters used to assess target volume coverage, conformity and homogeneity included V95 of the PTV (volume encompassed by the 95% isodose), conformity index ( CI ) and homogeneity index ( HI ). In addition, OAR maximum point doses, V20, V30, non‐target tissue ( NTT ) point max doses, NTT volume above reference dose, monitor units ( MU ) were compared. Results IMRT and VMAT plans generated were comparable for CI ( P = 0.12) and HI ( P = 0.89). VMAT plans achieved better V95 ( P = < 0.001) and reduced V20 and V30 by 652 cubic centimetres (cc) (28.5%) and 425.7 cc (29.1%), respectively. VMAT increased MU delivered by 18% without a corresponding increase in NTT dose. Conclusion Compared with IMRT plans for LNPN , VMAT achieved comparable HI and CI .