四维超声对前列腺运动靶体积分辨能力的研究

目的 探究四维(4D)超声对运动靶体积分辨能力。方法 选用前列腺超声模型,分组对比研究应用4D超声在不同运动振幅(A)及运动周期(T)下勾画前列腺靶区,模拟A值分别设置为0.5、1.0、2.0、3.0、4.0、5.0 mm,t值设为1、2、3、4s。分别计算模体前列腺靶体积,并以靶区静止时超声图像作为对照,分析两者间差异。结果 模体静止时超声靶体积与CT靶体积大小有较高一致性(P>0.05)。A值为0.5、1.0 mm,t值为1~4s时的体积与静止时超声靶体积相近(均P>0.05);A值为2.0、3.0 mm,t值为1~3s时靶体积与静止时超声靶体积不同(均P<0.05)。A值为2.0 mm,t值为4s时靶体积与静止时超声靶体积相近(P=0.710),组内极差为6.7cm³,标准差为1.15cm³;A值为3.0 mm,t值为4.0s时靶体积重复性差,组内极差为14.4cm³;A值为4.0、5.0 mm,t值为1~4s时组内极差分别为3.27~17.63cm³、6.51~21.02cm³。各周期下靶体积重复性很差,不能满足临床要求。结论 4D维超声可在患者运动周期1~4s内、运动幅度≤1 mm内为患者靶区勾画提供可靠参考数据,探头初始位置无影响。

Study of volume resolution of prostate motion target by four-dimensional ultrasound

Objective To explore the volume resolution of prostate motion target by four-dimensional (4D) ultrasound. Methods The prostate ultrasound model was selected, and the group comparison study was conducted using 4D ultrasound to outline the prostate target under different motion amplitudes (A) and motion period (T). The simulated A value was set as 0.5 mm, 1 mm, 2 mm, 3 mm, 4 mm, and 5 mm, respectively. The T value was set as 1s, 2s, 3s, and 4s, respectively. The volume of the target of the model prostate was calculated, and the static ultrasound image of the target was used as the control group to analyze the difference between two groups. Results When the model was still, the size of the target of ultrasound was consistent with that of CT scan (P>0.05). When the A values were 0.5 mm and 1 mm, there was no statistical difference between the volume in period 1-4s and the volume in the target at rest (all P>0.05). When the A values were 2 mm and 3 mm, and the T values were 1s, 2s and 3s there was statistical difference between the volume of target and that of of static ultrasonic target (all P<0.05). When the A value was 2 mm and the T value was 4s, there was no statistical difference between the target volume and the static target volume (P=0.710). The range within the group was 6.7cm³, and the standard deviation was 1.15cm³. When the A value was 3 mm and the T value was 4s, the volume repeatability of the target was poor, and the range within the group was 14.4cm³;when the A values were 4 mm and 5 mm, and the T values were 1-4s, the range within the group was 3.27-17.63cm³ and 6.51-21.02cm³, respectively. The volume repeatability of the target under each period was extremely poor, which could not meet the clinical requirements. Conclusion 4D ultrasound can provide reliable reference data for patients' target delineation within 1-4s of motion cycle and within 1 mm of motion amplitude, which exerts on effect upon the original position of probe.