Szabó Zoltán, Agoston Péter, Major Tibor, Horváth Katalin, Jederán Eva, Polgár Csaba
Sugárterápiás Központ, Országos Onkológiai Intézet, Budapest, Hungary.
Magy Onkol. 2012 Dec;56(4):267-73. Epub 2012 Mar 14.
The aim of the study was to compare clinical target volumes defined by CT and MRI for 3 dimensional conformal external beam radiotherapy of prostate cancer. CT and T2-weighed MRI images with 3 mm slice thickness were acquired for 13 patients with clinically organ-confined prostate cancer. Target volumes were contoured by two clinicians ("AP" and "SZ") experienced in prostate radiotherapy. Two clinical target volumes were defined: prostate (CTVpros) and prostate with a margin including the proximal 1 cm of the seminal vesicles (CTVpvs). Eight clinical target volumes were outlined for all patients: CTVprosAPCT, CTVprosAPMR, CTVpvsAPCT, CTVpvsAPMR, CTVprosSZCT, CTVprosSZMR, CTVpvsSZCT, CTVpvsSZMR. Volumes were measured in cm3. The volumes of different PTVs were compared using the Student's t-test. Mean CTVpros and CTVpvs using CT vs. MRI were 36.9 (range:13.8-121) vs. 32.0 (9.7-120.1) (p=0.0002), and 77.2 (30.5-209.5) vs. 67.6 (29.8-191.1) (p=0.0001), respectively. Mean CTVprosAPCT vs. CTVprosAPMR were 39.2 vs. 32.0 (p<0.00005), respectively. Mean CTVprosSZCT vs. CTVprosSZMR were 34.6 vs. 31.9 (p=0.15). Mean CTVpvsAPCT vs. CTVpvsAPMR were 85.8 vs. 70.9 (p<0.00006). Mean CTVpvsSZCT vs. CTVpvsSZMR were 68.6 vs. 64.4 (p=0.14). Interobserver difference for CTVpros defined by CT images was significant (39.2 vs. 34.6; p=0,0058). However, the difference was not significant using MRI images (32.0 vs. 31.9; p=0.93). Interobserver differences for CTVpvs were significant using either CT (85.8 vs. 68.6; p=0.0001) or MRI (70.9 vs. 64.4; p=0.004). Ratio of mean volumes contoured by the two observers were 1,12 (CT) vs. 1 (MRI) for CTVpros and 1,2 (CT) vs. 1,09 (MRI) for CTVpvs. Clinical target volumes defined for prostate cancer external beam radiotherapy by MRI images are significantly smaller compared to CT image based contouring. The magnitudes of differences are observer dependent. The use of MRI decreases the interobserver difference of mean volumes with 11% and 12% for CTVpvs and CTVpros.
本研究的目的是比较CT和MRI所定义的临床靶区体积，用于前列腺癌的三维适形外照射放疗。对13例临床诊断为器官局限性前列腺癌的患者进行了层厚为3mm的CT和T2加权MRI图像采集。由两位有前列腺放疗经验的临床医生（“AP”和“SZ”）勾勒靶区体积。定义了两个临床靶区：前列腺（CTVpros）和包含精囊近端1cm边缘的前列腺（CTVpvs）。为所有患者勾勒出八个临床靶区：CTVprosAPCT、CTVprosAPMR、CTVpvsAPCT、CTVpvsAPMR、CTVprosSZCT、CTVprosSZMR、CTVpvsSZCT、CTVpvsSZMR。体积以cm³为单位测量。使用学生t检验比较不同PTV的体积。CT与MRI测量的平均CTVpros分别为36.9（范围：13.8 - 121）和32.0（9.7 - 120.1）（p = 0.0002），平均CTVpvs分别为77.2（30.5 - 209.5）和67.6（29.8 - 191.1）（p = 0.0001）。平均CTVprosAPCT与CTVprosAPMR分别为39.2和32.0（p < 0.00005）。平均CTVprosSZCT与CTVprosSZMR分别为34.6和31.9（p = 0.15）。平均CTVpvsAPCT与CTVpvsAPMR分别为85.8和70.9（p < 0.00006）。平均CTVpvsSZCT与CTVpvsSZMR分别为68.6和64.4（p = 0.14）。CT图像所定义的CTVpros的观察者间差异显著（39.2对34.6；p = 0.0058）。然而，使用MRI图像时差异不显著（32.0对31.9；p = 0.93）。CTVpvs的观察者间差异在使用CT（85.8对68.6；p = 0.0001）或MRI（70.9对64.4；p = 0.004）时均显著。两位观察者勾勒的平均体积之比，CTVpros在CT时为1.12，在MRI时为1；CTVpvs在CT时为1.2，在MRI时为1.09。与基于CT图像的轮廓相比，MRI图像所定义的前列腺癌外照射放疗临床靶区体积显著更小。差异的大小取决于观察者。使用MRI可使CTVpvs和CTVpros的平均体积观察者间差异分别降低11%和12%。
