tailieunhanh - Báo cáo khoa học: " Four-dimensional dosimetry validation and study in lung radiotherapy using deformable image registration and Monte Carlo techniques"

Tuyển tập các báo cáo nghiên cứu về y học được đăng trên tạp chí y học Radiation Oncology cung cấp cho các bạn kiến thức về ngành y đề tài: Four-dimensional dosimetry validation and study in lung radiotherapy using deformable image registration and Monte Carlo techniques. | Huang etal. Radiation Oncology 2010 5 45 http content 5 1 45 RADIATION ONCOLOGY RESEARCH Open Access Four-dimensional dosimetry validation and study in lung radiotherapy using deformable image registration and Monte Carlo techniques Tzung-Chi Huang1 Ji-An Liang1 2 Thomas Dilling3 Tung-Hsin Wu 4 and Geoffrey Zhang3 Abstract Thoracic cancer treatment presents dosimetric difficulties due to respiratory motion and lung inhomogeneity. Monte Carlo and deformable image registration techniques have been proposed to be used in four-dimensional 4D dose calculations to overcome the difficulties. This study validates the 4D Monte Carlo dosimetry with measurement compares 4D dosimetry of different tumor sizes and tumor motion ranges and demonstrates differences of dosevolume histograms DVH with the number of respiratory phases that are included in 4D dosimetry. BEAMnrc was used in dose calculations while an optical flow algorithm was used in deformable image registration and dose mapping. Calculated and measured doses of a moving phantom agreed within 3 at the center of the moving gross tumor volumes GTV . 4D CT image sets of lung cancer cases were used in the analysis of 4D dosimetry. For a small tumor cm3 with motion range of cm reduced tumor volume coverage was observed in the 4D dose with a beam margin of 1 cm. For large tumors and tumors with small motion range around 1 cm the 4D dosimetry did not differ appreciably from the static plans. The dose-volume histogram DVH analysis shows that the inclusion of only extreme respiratory phases in 4D dosimetry is a reasonable approximation of all-phase inclusion for lung cancer cases similar to the ones studied which reduces the calculation in 4D dosimetry. Introduction Monte Carlo simulation is the most accurate radiation dose calculation algorithm in radiotherapy 1 2 . With the advent of increasingly fast computers and optimized computational algorithms Monte Carlo methods promise to become the primary