Prog Med Phys.  2019 Mar;30(1):1-6. 10.14316/pmp.2019.30.1.1.

Skin Dose Comparison of CyberKnife and Helical Tomotherapy for Head-and-Neck Stereotactic Body Radiotherapy

Affiliations
  • 1Department of Radiation Oncology, Seoul National University Hospital, Seoul, Korea.
  • 2Department of Radiation Oncology, Yonsei Cancer Center, Yonsei University College of Medicine, Seoul, Korea.
  • 3Department of Radiation Oncology, Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul, Korea. holee@yuhs.ac

Abstract

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 head-and-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.

Keyword

CyberKnife; Skin dose; Helical TomoTherapy; SBRT

MeSH Terms

Burns
Forehead
Radiosurgery*
Radiotherapy, Intensity-Modulated*
Skin*
Uncertainty
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