4-D IMRT: Imaging, Planning and Delivery

描述(申请人提供)：过去十年进行的研究表明，对于肺癌，增加放射治疗剂量将导致更好的局部控制和生存。进一步的研究表明，肺癌放射治疗的主要副作用-肺炎，可以通过降低对健康肺组织的剂量来显著减少。平衡这些相互冲突的目标是困难的，特别是在肺部肿瘤随着呼吸运动平均移动1.5-2厘米的情况下。该项目旨在开发和实施一种名为4D IMRT(4维强度调制放射治疗)的技术。该技术的第四维或时间部分意味着在成像、计划和放射治疗期间考虑肿瘤的运动。在治疗期间用辐射束跟踪肿瘤，可以减少射束边缘，从而减少暴露在高剂量下的健康组织的体积。调强放射治疗技术的组成部分允许我们对肿瘤给予足够高的剂量，而对健康肺组织给予可接受的低剂量。我们将探讨这样的假设：1.与传统的调强放疗相比，4D调强放疗的治疗计划有所改进；2.与传统的调强放疗相比，正常组织暴露在损伤剂量下的体积减少；3.与呼吸门控调强放疗相比，4D调强放疗的投放时间缩短；4.比屏气技术适用范围更广；5.与传统技术和呼吸门控技术相比，投放剂量分布的准确性更高。虽然这里的研究将主要集中在肺癌上，但4D调强放疗适用于所有受呼吸运动影响的部位，包括乳腺癌和肝癌，甚至宫颈癌和前列腺癌。

DESCRIPTION (provided by applicant): Studies performed over the past decade give evidence that for lung cancer, increased radiotherapy dose will lead to better local control and survival. Further studies show that the main lung cancer radiotherapy side effect, pneumonitis, can be significantly reduced by lowering the dose delivered to healthy lung tissue. Balancing these conflicting goals is difficult, especially since a lung tumor moves on average 1.5-2 cm with respiratory motion. This project aims to develop and implement a technique entitled 4D IMRT (4-Dimensional Intensity Modulated Radiation Therapy). The 4th dimension, or time, component of the technique means that the tumor motion is accounted for during the imaging, planning and delivery of radiation. Tracking the tumor with the radiation beam during treatment delivery allows a reduction in beam margin and consequently a reduction in the volume of healthy tissue exposed to a high dose. The IMRT component of the technique allows us to give a sufficiently high dose to the tumor and an acceptably low dose to the healthy lung tissue. We will investigate the hypotheses that 4D IMRT will lead to: 1. improved treatment plans compared with conventional IMRT, 2. reduced volumes of normal tissue exposed to injurious doses compared with conventional IMRT, 3. reduced delivery time compared with respiration-gated IMRT, 4. wider applicability than breath-hold techniques, and 5. higher accuracy in delivered dose distributions compared with conventional and respiration-gated techniques.Though the studies here will concentrate mainly on lung cancer, 4D IMRT is applicable to all sites affected by respiratory motion, including breast and liver cancer, and even cervix and prostate cancer.