PDF(Pubmed)
Abstract：
UNASSIGNED: In concurrent chemoradiotherapy for advanced esophageal cancer, a 2-phase method consisting of initial irradiation of a wide elective nodal region and boost irradiation of the primary lesion is commonly employed. Although dose escalation to the primary lesion may be required to achieve higher local control rates, the radiation dose to critical organs must not exceed dose constraints. To achieve an optimum balance of dose prescription and dose reduction to surrounding organs, such as the lungs and heart, we compared hybrid dose distributions and investigated the best combination of the following recent irradiation techniques: volumetric modulation arc therapy (VMAT), proton broad-beam irradiation, and intensity-modulated proton beam therapy (IMPT).
UNASSIGNED: Forty-five patients with advanced esophageal cancer whose primary lesions were located in the middle- or lower-thoracic region were studied. Radiotherapy plans for the initial and boost irradiation in the 2-phase method were calculated using VMAT, proton broad-beam irradiation, and IMPT calculation codes, and the dose-volume histogram indices of the lungs and heart for the accumulated plans were compared.
UNASSIGNED: In plans using boost proton irradiation with a prescribed dose of 60 Gy(RBE), all dose-volume histogram indices were significantly below the tolerance limits. Initial and boost irradiation with VMAT resulted in the median dose of V30 Gy(RBE)(heart) of 27.4% and an achievement rate below the tolerance limit of 57.8% (26 cases). In simulations of dose escalation up to 70 Gy(RBE), initial and boost IMPT resulted in the highest achievement rate, satisfying all dose constraints in 95.6% (43 cases).
UNASSIGNED: Applying VMAT to both initial and boost irradiation is not recommended because of the increased risk of the cardiac dose exceeding the tolerance limit. IMPT may allow dose escalation of up to 70 Gy(RBE) without radiation risks to the lungs and heart in the treatment of advanced esophageal cancer.
UNASSIGNED: Forty-five patients with advanced esophageal cancer whose primary lesions were located in the middle- or lower-thoracic region were studied. Radiotherapy plans for the initial and boost irradiation in the 2-phase method were calculated using VMAT, proton broad-beam irradiation, and IMPT calculation codes, and the dose-volume histogram indices of the lungs and heart for the accumulated plans were compared.
UNASSIGNED: In plans using boost proton irradiation with a prescribed dose of 60 Gy(RBE), all dose-volume histogram indices were significantly below the tolerance limits. Initial and boost irradiation with VMAT resulted in the median dose of V30 Gy(RBE)(heart) of 27.4% and an achievement rate below the tolerance limit of 57.8% (26 cases). In simulations of dose escalation up to 70 Gy(RBE), initial and boost IMPT resulted in the highest achievement rate, satisfying all dose constraints in 95.6% (43 cases).
UNASSIGNED: Applying VMAT to both initial and boost irradiation is not recommended because of the increased risk of the cardiac dose exceeding the tolerance limit. IMPT may allow dose escalation of up to 70 Gy(RBE) without radiation risks to the lungs and heart in the treatment of advanced esophageal cancer.
摘要：
■在晚期食管癌的同步放化疗中，通常采用两阶段方法，该方法包括对宽选择性结节区域进行初始照射和对原发病变进行增强照射。尽管可能需要将剂量递增至原发病灶以实现更高的局部控制率，对关键器官的辐射剂量不得超过剂量限制。为了实现剂量处方和对周围器官的剂量减少的最佳平衡，比如肺和心脏，我们比较了混合剂量分布，并研究了以下最新辐照技术的最佳组合：体积调制电弧治疗（VMAT），质子宽束辐照，和强度调制质子束治疗(IMPT)。
■研究了45例原发性病变位于中胸或下胸区域的晚期食管癌患者。使用VMAT计算了2阶段方法中初始和加强照射的放射治疗计划，质子宽束辐照，和IMPT计算代码，并比较了累积计划的肺和心脏的剂量-体积直方图指标。
■在使用规定剂量为60Gy（RBE）的增强质子辐照的计划中，所有剂量-体积直方图指数均显著低于耐受限值.用VMAT进行初始和加强照射导致V30Gy（RBE）（心脏）的中位剂量为27.4％，实现率低于57.8％的耐受极限（26例）。在剂量递增至70Gy(RBE)的模拟中，初始和提升IMPT导致最高的成就率，满足所有剂量限制的95.6%(43例)。
■不建议将VMAT同时应用于初始和增强照射，因为心脏剂量超过耐受极限的风险增加。在晚期食道癌的治疗中,IMPT可以允许高达70Gy(RBE)的剂量递增,而对肺和心脏没有放射风险。
■研究了45例原发性病变位于中胸或下胸区域的晚期食管癌患者。使用VMAT计算了2阶段方法中初始和加强照射的放射治疗计划，质子宽束辐照，和IMPT计算代码，并比较了累积计划的肺和心脏的剂量-体积直方图指标。
■在使用规定剂量为60Gy（RBE）的增强质子辐照的计划中，所有剂量-体积直方图指数均显著低于耐受限值.用VMAT进行初始和加强照射导致V30Gy（RBE）（心脏）的中位剂量为27.4％，实现率低于57.8％的耐受极限（26例）。在剂量递增至70Gy(RBE)的模拟中，初始和提升IMPT导致最高的成就率，满足所有剂量限制的95.6%(43例)。
■不建议将VMAT同时应用于初始和增强照射，因为心脏剂量超过耐受极限的风险增加。在晚期食道癌的治疗中,IMPT可以允许高达70Gy(RBE)的剂量递增,而对肺和心脏没有放射风险。
