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: 7523010
• 负责人: THOMAS R. BORTFELD
• 金额: $ 28.21万
• 依托单位: MASSACHUSETTS GENERAL HOSPITAL
• 依托单位国家: 美国
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-09-25 至 2013-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7523010
• 关键词: Address; Affect; Articular Range of Motion; Biological; Characteristics; Clinic; Depth; 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; Numbers; Organ; PET/CT scan; Patients; Positioning Attribute; Positron; Proton Radiation; Protons; Radiation therapy; Range; Range of motion exercise; Residual state; Simulate; Structure; System; Technology; Testing; Tissues; Today; Translating; Uncertainty; Validation; Variant; X-Ray Computed Tomography; clinically relevant; day; design; dosimetry; falls; heart motion; improved; in vivo; irradiation; 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.

质子放射治疗的主要物理优势是患者体内质子的范围有限。 然而，当今实践的质子治疗计划和实施受到相当大的影响。 该范围的不确定性以及因此远端剂量下降区域的位置的不确定性。我们的总体目标是 在临床上充分利用物理质子的优势，即射程。我们假设， 主要通过使用先进的成像技术，我们可以大幅降低范围不确定性， 并在准静态情况下将输送到患者的剂量深度位置控制在1毫米以内， 存在分数内运动时，误差在 3 毫米以内。我们进一步假设这将导致 显着提高目标覆盖范围和/或减少对附近关键结构的剂量。为了满足 总体目标并测试我们将努力实现 3 个具体目标的假设。目标 1 是缩小射程 静态场景中的不确定性。它涉及通过过滤方法减少 CT 金属伪影 以及更高能量的使用。它还解决了 CT 数到阻止本领的转换问题， 需要精确的剂量计算。将开发蒙特卡罗剂量计算方法。我们将 不仅旨在高精度计算质子射程，而且还研究由于 组织异质性，这导致远端剂量下降的陡度降低。目标2是范围 存在器官运动时的控制。在这里，我们将介绍时空（4D）成像技术 分析运动特征，并在数字模型中模拟器官运动。我们将重点关注门控 减轻动议影响的策略。我们还将致力于改善定位和固定 精度，例如光学成像技术。第三个目标是验证可达到的水平 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实用性 使用质子治疗部分后直接进行的 PET/CT 扫描进行测量。我们也会做幻影 在静态体模和生物运动体模（猪肺）中进行测量。最后，我们将 测量高能质子束穿过患者后的剩余射程，并将其与 预期值。所有目标通常适用于被动散射质子治疗和 IMPT。 总体而言，该项目将展示质子的主要物理优势（即有限范围）到什么程度 可以转化为患者的剂量学优势。其临床相关性将在以下研究中进行研究 项目 1 和项目 2。