Purpose: This study conducts a comparative evaluation of the skin dose in CyberKnife (CK) and
Helical Tomotherapy (HT) to predict the accurate dose of radiation and minimize skin burns in headand-
neck stereotactic body radiotherapy.
Materials and Methods: Arbitrarily-defined planning target volume (PTV) close to the skin was
drawn on the planning computed tomography acquired from a head-and-neck phantom with 19
optically stimulated luminescent dosimeters (OSLDs) attached to the surface (3 OSLDs were
positioned at the skin close to PTV and 16 OSLDs were near sideburns and forehead, away from
PTV). The calculation doses were obtained from the MultiPlan 5.1.2 treatment planning system
using raytracing (RT), finite size pencil beam (FSPB), and Monte Carlo (MC) algorithms for CK. For
HT, t he s kin d ose w as e stimated v ia c onvolution s uperposition ( CS) a lgorithm f rom t he
Tomotherapy planning station 5.0.2.5. The prescribed dose was 8 Gy for 95% coverage of the PTV.
Results and Conclusions: The mean differences between calculation and measurement values
were −1.2±3.1%, 2.5±7.9%, −2.8±3.8%, −6.6±8.8%, and −1.4±1.8% in CS, RT, RT with contour
correction (CC), FSPB, and MC, respectively. FSPB showed a dose error comparable to RT. CS and
RT with CC led to a small error as compared to FSPB and RT. Considering OSLDs close to PTV, MC
minimized the uncertainty of skin dose as compared to other algorithms.