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首页> 外文学位 >Image guided radiation therapy applications for head and neck, prostate, and breast cancers using 3D ultrasound imaging and Monte Carlo dose calculations.
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Image guided radiation therapy applications for head and neck, prostate, and breast cancers using 3D ultrasound imaging and Monte Carlo dose calculations.

机译：使用3D超声成像和蒙特卡洛剂量计算，针对头颈部，前列腺癌和乳腺癌的图像引导放射疗法应用。

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摘要

In radiation therapy an uncertainty in the delivered dose always exists because anatomic changes are unpredictable and patient specific. Image guided radiation therapy (IGRT) relies on imaging in the treatment room to monitor the tumour and surrounding tissue to ensure their prescribed position in the radiation beam. The goal of this thesis was to determine the dosimetric impact on the misaligned radiation therapy target for three cancer sites due to common setup errors; organ motion, tumour tissue deformation, changes in body habitus, and treatment planning errors. For this purpose, a novel 3D ultrasound system (Restitu, Resonant Medical, Inc.) was used to acquire a reference image of the target in the computed tomography simulation room at the time of treatment planning, to acquire daily images in the treatment room at the time of treatment delivery, and to compare the daily images to the reference image. The measured differences in position and volume between daily and reference geometries were incorporated into Monte Carlo (MC) dose calculations. The EGSnrc (National Research Council, Canada) family of codes was used to model Varian linear accelerators and patient specific beam parameters, as well as to estimate the dose to the target and organs at risk under several different scenarios.;In collaboration with the manufacturer, the ultrasound system was adapted from transabdominal imaging to neck imaging. Two case studies of nasopharyngeal cancer are discussed. The deformation of disease-positive cervical lymph nodes was monitored throughout treatment. Node volumes shrunk to 17% of the initial volume, moved up 1.3 cm, and received up to a 12% lower dose than that prescribed. It is shown that difficulties in imaging soft tissue in the neck region are circumvented with ultrasound imaging, and after dosimetric verification it is argued that adaptive replanning may be more beneficial than patient realignment when intensity modulated radiation therapy techniques are used.;Some of the largest dose delivery errors were found in external electron beam treatments for breast cancer patients who underwent breast conserving surgery. Inaccuracies in conventional treatment planning resulted in substantial target dose discrepancies of up to 88%. When patient setup errors, interfraction tumour bed motion, and tissue remodeling were considered, inadequate target coverage was exacerbated.;This thesis quantifies the dose discrepancy between that prescribed and that delivered. I delve into detail for common IGRT treatment sites, and illuminate problems that have not received much attention for less common IGRT treatment sites.;After validating the necessity of MC dose calculations in the pelvic region, the impact of interfraction prostate motion, and subsequent patient realignment under the treatment beams, on the delivered dose was investigated. For 32 patients it is demonstrated that using 3D conformal radiation therapy techniques and a 7 mm margin, the prescribed dose to the prostate, rectum, and bladder is recovered within 0.5% of that planned when patient setup is corrected for prostate motion, despite the beams interacting with a new external surface and internal tissue boundaries.
机译：在放射治疗中，由于解剖变化是不可预测的且因患者而异，因此始终存在输送剂量的不确定性。图像引导放射疗法（IGRT）依靠治疗室中的成像来监视肿瘤和周围组织，以确保其在放射束中的指定位置。本文的目的是确定由于常见设置错误而导致的三个癌症部位对未对准放射治疗靶标的剂量学影响。器官运动，肿瘤组织变形，身体习性变化和治疗计划错误。为此，在治疗计划时，使用了新型3D超声系统（Restitu，Resonant Medical，Inc.）在计算机断层扫描模拟室中获取目标的参考图像，并在进行治疗的时间，并将每日图像与参考图像进行比较。每日和参考几何之间的位置和体积的测量差异已合并到Monte Carlo（MC）剂量计算中。 EGSnrc（加拿大国家研究委员会）代码系列用于对Varian线性加速器和患者特定的射束参数进行建模，以及在几种不同情况下估算目标和处于危险中的器官的剂量。 ，超声系统已从经腹成像改为颈部成像。讨论了两个鼻咽癌病例研究。在整个治疗过程中监测疾病阳性宫颈淋巴结的变形。结节体积缩小至初始体积的17％，向上移动1.3厘米，并比规定的剂量降低多达12％。结果表明，超声成像可以规避颈部软组织成像的困难，并且在剂量学验证之后，当使用强度调制放射治疗技术时，适应性重新计划可能比患者重新调整更为有益。在接受保乳手术的乳腺癌患者的外部电子束治疗中发现剂量输送错误。传统治疗计划中的错误导致目标剂量差异高达88％。当考虑到患者设置错误，间质性肿瘤床运动和组织重塑时，目标覆盖率不足会加剧。;本论文量化了处方药和给药药之间的剂量差异。我详细研究了常见的IGRT治疗部位，并阐明了不太常见的IGRT治疗部位尚未引起足够重视的问题。;在确认骨盆区域进行MC剂量计算的必要性，分行前列腺运动的影响以及随后的患者研究了在治疗光束下的重新对准，对所提供的剂量。对于32例患者，证明了使用3D适形放射治疗技术和7 mm的余量，尽管校正了光束，但校正了患者的前列腺运动后，前列腺，直肠和膀胱的处方剂量可恢复到计划的0.5％以内与新的外表面和内部组织边界相互作用。

著录项

  • 作者

    Fraser, Danielle.;

  • 作者单位

    McGill University (Canada).;

  • 授予单位 McGill University (Canada).;
  • 学科 Physics Radiation.;Biophysics General.;Health Sciences Oncology.;Health Sciences Radiology.
  • 学位 Ph.D.
  • 年度 2010
  • 页码 194 p.
  • 总页数 194
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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