PDF(Pubmed)
Abstract：
UNASSIGNED: Postoperative radiotherapy after conservative surgery for patients with breast cancer usually includes focal over-irradiation (boost) to the surgical bed (SB). Irradiation planning using computed tomography (CT) is difficult in many cases because of insufficient intrinsic soft tissue contrast. To ensure appropriate radiation to the tumor, large boost volumes are delineated, resulting in a higher dose to the normal tissue. Magnetic resonance imaging (MRI) provides superior soft tissue contrast than CT and can better differentiate between normal tissue and the SB. However, for SB delineation CT images alone remain the pathway followed in patients undergoing breast irradiation. This study aimed to evaluate the potential advantages in boost dosimetry by using MRI and CT as pre-treatment imaging.
UNASSIGNED: Eighteen boost volumes were drawn on CT and MRI and elastically co-registered using commercial image registration software. The radiotherapy treatment plan was optimized using the CT volumes as the baseline. The dose distributions of the target volumes on CT and MRI were compared using dose-volume histogram cutoff points.
UNASSIGNED: The radiation volumes to the SB varied considerably between CT and MRI (conformity index between 0.24 and 0.67). The differences between the MRI and CT boost doses in terms of the volume receiving 98% of the prescribed dose (V98%) varied between 10% and 30%. Smaller differences in the V98% were observed when the boost volumes were delineated using MRI.
UNASSIGNED: Using MRI to delineate the volume of the SB may increase the accuracy of boost dosimetry.
UNASSIGNED: Eighteen boost volumes were drawn on CT and MRI and elastically co-registered using commercial image registration software. The radiotherapy treatment plan was optimized using the CT volumes as the baseline. The dose distributions of the target volumes on CT and MRI were compared using dose-volume histogram cutoff points.
UNASSIGNED: The radiation volumes to the SB varied considerably between CT and MRI (conformity index between 0.24 and 0.67). The differences between the MRI and CT boost doses in terms of the volume receiving 98% of the prescribed dose (V98%) varied between 10% and 30%. Smaller differences in the V98% were observed when the boost volumes were delineated using MRI.
UNASSIGNED: Using MRI to delineate the volume of the SB may increase the accuracy of boost dosimetry.
摘要：
■乳腺癌患者保守性手术后的术后放疗通常包括对手术床（SB）的局灶性过度照射（增强）。由于内在软组织对比度不足，因此在许多情况下很难进行使用计算机断层扫描（CT）的辐射计划。为了确保对肿瘤进行适当的辐射，描绘了大量的升压量，导致对正常组织的较高剂量。磁共振成像（MRI）提供比CT更好的软组织对比度，并且可以更好地区分正常组织和SB。然而,对于SB勾画，仅CT图像仍然是接受乳房照射的患者所遵循的路径。本研究旨在通过使用MRI和CT作为治疗前成像来评估增强剂量学的潜在优势。
■在CT和MRI上绘制18个增强体积,并使用商业图像配准软件进行弹性共配准。以CT体积为基线优化放射治疗计划。使用剂量-体积直方图截止点比较CT和MRI上目标体积的剂量分布。
■对SB的辐射量在CT和MRI之间变化很大（合格指数在0.24和0.67之间）。MRI和CT增强剂量之间的差异在接受98％的处方剂量（V98％）的体积方面在10％和30％之间变化。当使用MRI描绘增强体积时,观察到V98%的较小差异。
■使用MRI描绘SB的体积可能会提高增强剂量测定的准确性。
■在CT和MRI上绘制18个增强体积,并使用商业图像配准软件进行弹性共配准。以CT体积为基线优化放射治疗计划。使用剂量-体积直方图截止点比较CT和MRI上目标体积的剂量分布。
■对SB的辐射量在CT和MRI之间变化很大（合格指数在0.24和0.67之间）。MRI和CT增强剂量之间的差异在接受98％的处方剂量（V98％）的体积方面在10％和30％之间变化。当使用MRI描绘增强体积时,观察到V98%的较小差异。
■使用MRI描绘SB的体积可能会提高增强剂量测定的准确性。
