肺部立体定向体部放射治疗：根据肿瘤位置和 4DCT 扫描次数制定个体化 PTV 边界。
Lung stereotactic body radiation therapy: personalized PTV margins according to tumor location and number of four-dimensional CT scans.
机构信息
Department of Radiation Oncology, Institut de Cancérologie de L'Ouest Angers, 15 Rue A Boquel, 49055, Angers Cedex 02, France.
Department of Medical Physics, Institut de Cancérologie de L'Ouest Angers, 15 Rue A Boquel, 49055, Angers Cedex 02, France.
出版信息
Radiat Oncol. 2022 Jan 10;17(1):5. doi: 10.1186/s13014-021-01973-5.
OBJECTIVES
To characterise the motion of pulmonary tumours during stereotactic body radiation therapy (SBRT) and to evaluate different margins when creating the planning target volume (PTV) on a single 4D CT scan (4DCT).
METHODS
We conducted a retrospective single-site analysis on 30 patients undergoing lung SBRT. Two 4DCTs (4DCT1 and 4DCT2) were performed on all patients. First, motion was recorded for each 4DCT in anterior-posterior (AP), superior-inferior (SI) and rightleft (RL) directions. Then, we used 3 different margins (3,4 and 5 mm) to create the PTV, from the internal target volume (ITV) of 4DCT1 only (PTV D1 + 3, PTV D1 + 4, PTV D1 + 5). We compared, using the Dice coefficient, the volumes of these 3 PTVs, to the PTV actually used for the treatment (PTV). Finally, new treatment plans were calculated using only these 3 PTVs. We studied the ratio of the D2%, D50% and D98% between each new plan and the plan actually used for the treatment (D2% PTV, D50% PTV, D50% ITVttt D98% PTV).
RESULTS
30 lesions were studied. The greatest motion was observed in the SI axis (8.8 ± 6.6 [0.4-25.8] mm). The Dice index was higher when comparing PTVttt to PTV D1 + 4 mm (0.89 ± 0.04 [0.82-0.98]). Large differences were observed when comparing plans relative to PTVttt and PTV D1 + 3 for D98% PTV (0.85 ± 0.24 [0.19-1.00]). and also for D98% ITV (0.93 ± 0.12 [0.4-1.0]).D98% PTV (0.85 ± 0.24 [0.19-1.00], p value = 0.003) was statistically different when comparing plans relative to PTV and PTV D1 + 3. No stastistically differences were observed when comparing plans relative to PTV and PTV D1 + 4. A difference greater than 10% relative to D98% PTV was found for only in one UL lesion, located under the carina.
CONCLUSION
A single 4DCT appears feasible for upper lobe lesions located above the carina, using a 4-mm margin to generate the PTV.
ADVANCE IN KNOWLEDGE
Propostion of a personalized SBRT treatment (number of 4DCT, margins) according to tumor location (above or under the carina).
目的
描述立体定向体部放射治疗（SBRT）期间肺部肿瘤的运动，并评估在单次 4DCT 扫描（4DCT）上创建计划靶区（PTV）时不同的边界。
方法
我们对 30 名接受肺部 SBRT 的患者进行了回顾性单站点分析。所有患者均进行了两次 4DCT（4DCT1 和 4DCT2）。首先，在前后（AP）、上下（SI）和左右（RL）方向上记录每个 4DCT 的运动。然后，我们使用 3 种不同的边界（3、4 和 5mm）从仅 4DCT1 的内部靶区（ITV）创建 PTV（PTV D1+3、PTV D1+4、PTV D1+5）。我们使用 Dice 系数比较了这 3 个 PTV 的体积与实际用于治疗的 PTV（PTV）。最后，仅使用这 3 个 PTV 计算了新的治疗计划。我们研究了每个新计划与实际用于治疗的计划（D2%PTV、D50%PTV、D50%ITVttt D98%PTV）之间的 D2%、D50%和 D98%的比值。
结果
研究了 30 个病灶。最大运动发生在 SI 轴上（8.8±6.6[0.4-25.8]mm）。与 PTV D1+4mm 相比，PTVttt 的 Dice 指数更高（0.89±0.04[0.82-0.98]）。与 PTVttt 和 PTV D1+3 相比，D98%PTV（0.85±0.24[0.19-1.00]）和 D98%ITV（0.93±0.12[0.4-1.0]）的差异较大。与 PTV D1+3 相比，D98%PTV（0.85±0.24[0.19-1.00]，p 值=0.003）的差异具有统计学意义。与 PTV D1+4 相比，没有观察到与计划相关的差异。仅在一个位于隆突下的 UL 病灶中发现了与 D98%PTV 相差大于 10%的差异。
结论
对于位于隆突上方的上叶病灶，单次 4DCT 似乎可以使用 4mm 边界生成 PTV 来实现。
知识进步
根据肿瘤位置（隆突上方或下方）提出个性化 SBRT 治疗（4DCT 次数、边界）的建议。
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