Reducing Range Uncertainties in Proton Radiation Therapy

减少质子放射治疗的范围不确定性

• 批准号: 8336787
• 负责人: THOMAS R. BORTFELD
• 金额: $ 5.03万
• 依托单位: MASSACHUSETTS GENERAL HOSPITAL
• 依托单位国家: 美国
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-09-21 至 2014-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8336787
• 关键词: Address; Affect; Articular Range of Motion; Biological; Characteristics; Clinic; Distal; Dose; Family suidae; Four-dimensional; Goals; Heterogeneity; Image; Imaging Techniques; Imaging technology; Immobilization; Lateral; Lead; Liquid substance; Lung; Malignant neoplasm of lung; Measurement; Measures; Metals; Methods; Morphologic artifacts; Motion; Organ; PET/CT scan; Patients; Positioning Attribute; Positron; Proton Radiation; Protons; Radiation therapy; Residual state; Scanning; Simulate; Structure; System; Technology; Testing; Therapeutic Studies; Tissues; Translating; Uncertainty; Validation; Variant; X-Ray Computed Tomography; clinically relevant; design; dosimetry; falls; heart motion; improved; in vivo; irradiation; meetings; optical imaging; physical property; proton beam; respiratory; treatment planning; treatment site; tumor

The main physical advantage of proton radiation therapy is the finite range of protons in the patient. However, proton treatment planning and delivery, as practiced today, is affected by considerable uncertainties in the range and therefore in the position of the distal dose fall-off region. Our overall goal is to utilize the physical proton advantage, i.e., the range, to its full extent in the clinic. We hypothesize that, mainly through the use of advanced imaging technology, we can reduce range uncertainties substantially, and control the depth position of the dose delivered to the patient to within 1 mm in the quasi-static case and within 3 mm in the presence of intra-fractional motion. We further hypothesize that this will lead to substantially improved target coverage and/or reduced dose to nearby critical structures. To meet the overall goal and test the hypotheses we will strive to achieve 3 Specific Aims. Aim 1 is the reduction of range uncertainties in the static scenario. It involves the reduction of CT metal artifacts through a filtering approach and the use of higher energies. It also addresses the conversion of CT numbers to stopping powers, which are needed for accurate dose calculation. Monte Carlo dose calculation methods will be developed. We will not only aim to calculate the proton range with great precision, but also to investigate range degradation due to tissue heterogeneities, which leads to a reduced steepness of the distal dose fall-off. Aim 2 is range control in the presence of organ motion. Here we will introduce spatio-temporal (4D) imaging techniques to analyze motion characteristics, and simulate organ motion in a numerical phantom. We will focus on gating strategies to mitigate the effects of the motion. We will also aim to improve positioning and immobilization accuracies, for example with optical imaging techniques. The third aim is to validate the achievable level of accuracy. This will be done in three ways. First we will investigate the feasibility and utility of in-vivo measurements using PET/CT scans taken directly after a proton treatment fraction. We will also do phantom measurements, both in a static phantom and in a biological motion phantom (swine lung). Finally, we will measure the residual range of an energetic proton beam after traversing the patient, and compare it with the expected value. All Aims are generally applicable to both passively scattered proton therapy and IMPT. Overall this project will show to what degree the primary physical advantage of protons (i.e., the finite range) can be translated into a dosimetric advantage in patients. The clinical relevance of this will be studied in Project 1 and Project 2.

质子辐射疗法的主要物理优势是患者的质子有限范围。 但是，如今所实践的质子治疗计划和交付受到相当大的影响 范围内的不确定性，因此在远端剂量下降区域的位置。我们的总体目标是 利用物理质子优势，即在诊所的全部范围。我们假设这一点， 主要通过使用高级成像技术，我们可以大大减少范围不确定性， 并控制在准静态病例中将给患者剂量的深度位置到1毫米以内 在存在分数内运动的情况下，在3毫米之内。我们进一步假设这将导致 大大改善了目标覆盖率和/或减少对附近关键结构的剂量。见面 总体目标并测试我们将努力实现3个具体目标的假设。 AIM 1是范围的减少 在静态场景中的不确定性。它涉及通过过滤方法减少CT金属伪像 以及更高能量的使用。它还解决了CT数字转换为停止权力的转换， 需要进行准确的剂量计算。将开发蒙特卡洛剂量计算方法。我们将 不仅要精确地计算质子范围，而且还要调查应得的范围降解 到组织异质性，导致远端剂量下降的陡度降低。 AIM 2是范围 控制器官运动的控制。在这里，我们将为时空（4D）成像技术介绍 分析运动特性，并在数值幻影中模拟器官运动。我们将专注于门控 减轻运动影响的策略。我们还将旨在改善定位和固定 精度，例如使用光学成像技术。第三个目的是验证可实现的水平 准确性。这将通过三种方式完成。首先，我们将研究体内的可行性和效用 使用PET/CT扫描直接在质子处理部分后进行的测量。我们还将做幻影 在静态幻影和生物运动幻影（猪肺）中进行的测量。最后，我们会的 穿越患者后，测量能量质子束的残留范围，并将其与 期望值。所有目标通常都适用于被动分散的质子疗法和IMPT。 总体而言，该项目将显示质子的主要物理优势在多大程度上（即有限范围） 可以将患者转化为剂量优势。将在此研究的临床相关性 项目1和项目2。