Modeling the transport of photons from source to detector as a means of improving radiation therapy by enhanced utilization of kV and MV x-ray imaging

对光子从源到探测器的传输进行建模，作为通过增强 kV 和 MV X 射线成像的利用来改进放射治疗的一种手段

• 批准号: RGPIN-2015-05623
• 负责人: McCurdy, Boyd
• 金额: $ 1.75万
• 依托单位: University of Manitoba
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2016
• 资助国家: 加拿大
• 起止时间: 2016-01-01 至 2017-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=613652
• 关键词: Modeling; transport; photons; source; detector

Introduction: This research program seeks to develop new algorithms to remove contaminating x-ray scatter from diagnostic and therapeutic medical images obtained in modern radiation therapy. Current radiation treatment units use kilovoltage (KV) x-rays for anatomical imaging (ie. cone-beam computed tomography, CBCT) just prior to therapy delivery using a megavoltage (MV) x-ray beam. Therapy and diagnostic imaging applications on these units are currently at a rudimentary level. Hypothesis: A hybrid scatter estimation algorithm for both MV and KV energy x-rays will improve the accuracy of image reconstruction and density conversion (CBCT) and also improve the accuracy of dose reconstruction (MV) providing increased sensitivity for error detection.  Objectives: 1. Develop a hybrid scatter estimation algorithm combining a deterministic approach with a novel, fast Monte Carlo method. 2. Validate and optimize this algorithm using both MV and KV x-ray beams. 3. Combine interleaved KV and MV imaging allowing diagnostic imaging during therapy delivery. Methods: Building on our previous experience, a hybrid algorithm will be developed to estimate x-ray scatter from patients for both KV and MV energy x-ray beams. A fast analytical solution will estimate singly-scattered x-rays, while a novel Monte Carlo approach treating each voxel as a scatter source will estimate multiply-scattered x-rays. The method will be validated on both MV therapeutic beams and KV (CBCT) diagnostic imaging beams and quantitatively evaluated in terms of reconstruction accuracy and improved contrast (CBCT), and patient reconstructed dose accuracy (MV) on a variety of geometric and anthropomorphic phantoms. Furthermore, an interleaved acquisition approach will be developed to concurrently obtain KV and MV image data during radiation treatment delivery through the use of XML control software, minimizing the impact of patient motion. Performance will be assessed through quantitative comparison of image quality results to standard sequential image acquisition. Significance: This research program will provide significantly improved quality CBCT data on radiation treatment units (i.e. improved tumour visibility, accurate density conversions). For MV imaging, more accurate patient dose reconstructions will be provided, improving sensitivity in detecting delivery errors. Interleaved image acquisition will provide a more accurate representation of patient anatomy during treatment. Future research opportunities for real-time tumour tracking and adaptive radiation therapy will be created. Conclusion: This research program builds on our experience developing scatter estimation algorithms and their applications to improve the accuracy of radiation treatments. Eventually these advances may be used throughout Canada and the world to improve quality of life for all patients treated with radiation.

简介：本研究计划旨在开发新的算法，以消除在现代放射治疗中获得的诊断和治疗医学图像中的污染x射线散射。目前的放射治疗单位使用千伏（KV） x射线进行解剖成像。锥形束计算机断层扫描（CBCT），在使用兆伏（MV） x射线束进行治疗之前。这些单位的治疗和诊断成像应用目前处于初级水平。