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Author Pokhrel, D. ♦ Sood, S. ♦ Badkul, R. ♦ Jiang, H. ♦ Saleh, H. ♦ Wang, F.
Source United States Department of Energy Office of Scientific and Technical Information
Content type Text
Language English
Subject Keyword APPLIED LIFE SCIENCES ♦ RADIATION PROTECTION AND DOSIMETRY ♦ ALGORITHMS ♦ BEAM MONITORS ♦ BEAMS ♦ COMPUTERIZED TOMOGRAPHY ♦ HEALTH HAZARDS ♦ IMAGES ♦ LUNGS ♦ MONTE CARLO METHOD ♦ NEOPLASMS ♦ NERVES ♦ NMR IMAGING ♦ PATIENTS ♦ RADIATION DOSE DISTRIBUTIONS ♦ RADIATION DOSES ♦ RADIOTHERAPY ♦ SINUSES ♦ SPINAL CORD ♦ X RADIATION
Abstract Purpose: To compare dose distributions calculated using PB-hete vs. XVMC algorithms for SRT treatments of cavernous sinus tumors. Methods: Using PB-hete SRT, five patients with cavernous sinus tumors received the prescription dose of 25 Gy in 5 fractions for planning target volume PTV(V100%)=95%. Gross tumor volume (GTV) and organs at risk (OARs) were delineated on T1/T2 MRI-CT-fused images. PTV (range 2.1–84.3cc, mean=21.7cc) was generated using a 5mm uniform-margin around GTV. PB-hete SRT plans included a combination of non-coplanar conformal arcs/static beams delivered by Novalis-TX consisting of HD-MLCs and a 6MV-SRS(1000 MU/min) beam. Plans were re-optimized using XVMC algorithm with identical beam geometry and MLC positions. Comparison of plan specific PTV(V99%), maximal, mean, isocenter doses, and total monitor units(MUs) were evaluated. Maximal dose to OARs such as brainstem, optic-pathway, spinal cord, and lenses as well as normal tissue volume receiving 12Gy(V12) were compared between two algorithms. All analysis was performed using two-tailed paired t-tests of an upper-bound p-value of <0.05. Results: Using either algorithm, no dosimetrically significant differences in PTV coverage (PTVV99%,maximal, mean, isocenter doses) and total number of MUs were observed (all p-values >0.05, mean ratios within 2%). However, maximal doses to optic-chiasm and nerves were significantly under-predicted using PB-hete (p=0.04). Maximal brainstem, spinal cord, lens dose and V12 were all comparable between two algorithms, with exception of one patient with the largest PTV who exhibited 11% higher V12 with XVMC. Conclusion: Unlike lung tumors, XVMC and PB-hete treatment plans provided similar PTV coverage for cavernous sinus tumors. Majority of OARs doses were comparable between two algorithms, except for small structures such as optic chiasm/nerves which could potentially receive higher doses when using XVMC algorithm. Special attention may need to be paid on a case-by-case basis when planning for sinus SRT based on tumor size and location to OARs particularly the optic apparatus.
ISSN 00942405
Educational Use Research
Learning Resource Type Article
Publisher Date 2015-06-15
Publisher Place United States
Journal Medical Physics
Volume Number 42
Issue Number 6


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