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Stanford University Details Findings in Medical Physics (Improving IMRT delivery efficiency with reweighted L1-minimization for inverse planning)

August 13, 2014



By a News Reporter-Staff News Editor at Biotech Week -- Current study results on Health and Medicine have been published. According to news reporting from Stanford, California, by NewsRx journalists, research stated, "This study presents an improved technique to further simplify the fluence-map in intensity modulated radiation therapy (IMRT) inverse planning, thereby reducing plan complexity and improving delivery efficiency, while maintaining the plan quality. First-order total-variation (TV) minimization (min.) based on L1-norm has been proposed to reduce the complexity of fluence-map in IMRT by generating sparse fluence-map variations."

The news correspondents obtained a quote from the research from Stanford University, "However, with stronger dose sparing to the critical structures, the inevitable increase in the fluence-map complexity can lead to inefficient dose delivery. Theoretically, L0-min. is the ideal solution for the sparse signal recovery problem, yet practically intractable due to its nonconvexity of the objective function. As an alternative, the authors use the iteratively reweighted L1-min. technique to incorporate the benefits of the L0-norm into the tractability of L1-min. The weight multiplied to each element is inversely related to the magnitude of the corresponding element, which is iteratively updated by the reweighting process. The proposed penalizing process combined with TV min. further improves sparsity in the fluence-map variations, hence ultimately enhancing the delivery efficiency. To validate the proposed method, this work compares three treatment plans obtained from quadratic min. (generally used in clinic IMRT), conventional TV min., and our proposed reweighted TV min. techniques, implemented by a large-scale L1-solver (template for first-order conic solver), for five patient clinical data. Criteria such as conformation number (CN), modulation index (MI), and estimated treatment time are employed to assess the relationship between the plan quality and delivery efficiency. The proposed method yields simpler fluence-maps than the quadratic and conventional TV based techniques. To attain a given CN and dose sparing to the critical organs for 5 clinical cases, the proposed method reduces the number of segments by 10-15 and 30-35, relative to TV min. and quadratic min. based plans, while MIs decreases by about 20%-30% and 40%-60% over the plans by two existing techniques, respectively. With such conditions, the total treatment time of the plans obtained from our proposed method can be reduced by 12-30 s and 30-80 s mainly due to greatly shorter multileaf collimator (MLC) traveling time in IMRT step-and-shoot delivery. The reweighted L1-minimization technique provides a promising solution to simplify the fluence-map variations in IMRT inverse planning."

According to the news reporters, the research concluded: "It improves the delivery efficiency by reducing the entire segments and treatment time, while maintaining the plan quality in terms of target conformity and critical structure sparing."

For more information on this research see: Improving IMRT delivery efficiency with reweighted L1-minimization for inverse planning. Medical Physics, 2013;40(7):071719. Medical Physics can be contacted at: Amer Assoc Physicists Medicine Amer Inst Physics, Ste 1 No 1, 2 Huntington Quadrangle, Melville, NY 11747-4502, USA. (American Association of Physicists in Medicine - www.aapm.org; Medical Physics - online.medphys.org/)

Our news journalists report that additional information may be obtained by contacting H. Kim, Dept. of Radiation Oncology, Stanford University, Stanford, California 94305-5847, United States. Additional authors for this research include S. Becker, R. Lee, S. Lee, S. Shin, E. Candes, L. Xing and R. Li (see also Health and Medicine).

Publisher contact information for the journal Medical Physics is: Amer Assoc Physicists Medicine Amer Inst Physics, Ste 1 No 1, 2 Huntington Quadrangle, Melville, NY 11747-4502, USA.

Keywords for this news article include: Stanford, California, United States, Health and Medicine, North and Central America.

Our reports deliver fact-based news of research and discoveries from around the world. Copyright 2014, NewsRx LLC


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Source: Biotech Week


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