Implementation of Constant Dose Rate and Constant Angular Spacing Intensity-modulated Arc Therapy for Cervical Cancer by Using a Conventional Linear Accelerator / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Volumetric-modulated arc therapy (VMAT) can only be implemented on the new generation linacs such as the Varian Trilogy® and Elekta Synergy®. This prevents most existing linacs from delivering VMAT. The purpose of this study was to investigate the feasibility of using a conventional linear accelerator delivering constant dose rate and constant angular spacing intensity-modulated arc therapy (CDR-CAS-IMAT) for treating cervical cancer.</p><p><b>METHODS</b>Twenty patients with cervical cancer previously treated with intensity-modulated radiation therapy (IMRT) using Varian Clinical 23EX were retreated using CDR-CAS-IMAT. The planning target volume (PTV) was set as 50.4 Gy in 28 fractions. Plans were evaluated based on the ability to meet the dose volume histogram. The homogeneity index (HI), target volume conformity index (CI), the dose to organs at risk, radiation delivery time, and monitor units (MUs) were also compared. The paired t-test was used to analyze the two data sets. All statistical analyses were performed using SPSS 19.0 software.</p><p><b>RESULTS</b>Compared to the IMRT group, the CDR-CAS-IMAT group showed better PTV CI (0.85 ± 0.03 vs. 0.81 ± 0.03, P = 0.001), clinical target volume CI (0.46 ± 0.05 vs. 0.43 ± 0.05, P = 0.001), HI (0.09 ± 0.02 vs. 0.11 ± 0.02, P = 0.005) and D95 (5196.33 ± 28.24 cGy vs. 5162.63 ± 31.12 cGy, P = 0.000), and cord D2 (3743.8 ± 118.7 cGy vs. 3806.2 ± 98.7 cGy, P = 0.017) and rectum V40 (41.9 ± 6.1% vs. 44.2 ± 4.8%, P = 0.026). Treatment time (422.7 ± 46.7 s vs. 84.6 ± 7.8 s, P = 0.000) and the total plan Mus (927.4 ± 79.1 vs. 787.5 ± 78.5, P = 0.000) decreased by a factor of 0.8 and 0.15, respectively. The IMRT group plans were superior to the CDR-CAS-IMAT group plans considering decreasing bladder V50 (17.4 ± 4.5% vs. 16.6 ± 4.2%, P = 0.049), bowel V30 (39.6 ± 6.5% vs. 36.6 ± 7.5%, P = 0.008), and low-dose irradiation volume; there were no significant differences in other statistical indexes.</p><p><b>CONCLUSIONS</b>Patients with cervical cancer treated with CDR-CAS-IMAT using Varian Clinical 23EX can get equivalent or superior dose distribution compared to those treated with IMRT. CDR-CAS-IMAT has a less treatment time and MU, which can reduce the uncertainty factor and patient discomfort in treatment.</p>

Relationship of gross tumor volume with lymph node metastasis and prognosis of esophageal carcinoma / 中华肿瘤杂志

<p><b>OBJECTIVE</b>To explore whether there is a relationship between gross tumor volume (GTV) and pathologic lymph node metastasis or prognosis of esophageal carcinoma, and to provide a new prognosis reference for esophageal carcinoma (EC).</p><p><b>METHODS</b>Six hundred and seven patients received radical resection of thoracic esophageal carcinoma from May 2002 to June 2006 in our hospital, and their pre-operative CT images were transmitted to the three-dimensional conformal radiotherapy planning system by the network in digital format. Esophageal GTV targets were outlined and their GTV volumes were calculated. To analyze whether there is a relationship between GTV volume and pathologic lymph node metastasis or prognosis.</p><p><b>RESULTS</b>In the 607 cases of esophageal carcinoma, the GTV volume was (22.5 ± 16.8) cm(3) in 374 stage N0 EC patients, significantly different from that of (30.4 ± 20.1) cm(3) in 233 stage N1 EC cases (P < 0.001). There is a significant difference between the GTV volumes of the groups with and without lymph node metastasis (P < 0.05). There was a significant difference of the GTV volumes of EC patients with one lymph node metastasis and those with ≥ 4 lymph node metastasis (P < 0.05). There was a positive correlation between GTV volume and the number of lymph node metastasis (r = 0.230, P < 0.001). The 1-, 3-, 5-year survival rates since the surgery date were 83.8%, 53.5%, and 36.4%, respectively. There was a significant difference between the survival rates of stage N0 (48.5%) and stage N1 patients (18.2%, P < 0.001), and there was a significant difference between the survival rats of patients with 0, 1 and ≥ 2 lymph node metastasis (P < 0.01). Cox regression model analysis showed that GTV volume, number of lymph node metastasis, pathological type, and lesion site were independent prognostic factors (all P < 0.05).</p><p><b>CONCLUSION</b>The GTV volume of esophageal carcinoma is positively correlated with the number of pathologic lymph node metastasis, and it is an independent prognostic factor for this cancer.</p>

Exploration of the classification of gross tumor volume and pathological staging of esophageal carcinoma / 中华肿瘤杂志

<p><b>OBJECTIVE</b>Using the volume calculating function of treatment planning system of 3DCRT to work out the value of GTV standard classifications and to provide the reference for clinical staging of esophageal carcinoma.</p><p><b>METHODS</b>Six hundred and seven patients underwent radical resection of thoracic esophageal carcinoma in our hospital, and their pre-operative CT images were transmitted in digital format to the three-dimensional conformal radiotherapy planning system by the network. Esophageal lesion GTV targets were outlined, and their volumes were automatically computed by the planning system. Compared the differences of the GTV volumes in different pathological T stages, and analyzed the relationship between GTV volumes and pathological T stages. According to the median volume of GTV at different pathological T stages, divided the values of GTV volume corresponding to different T stages and selected the suitable classification standard of GTV volume.</p><p><b>RESULTS</b>The esophageal carcinoma GTV length, maximum diameter and volume were related to pathological T staging and with a positive correlation (all P < 0.001). The Spearman correlation coefficient (r) was 0.376, 0.466 and 0.464, respectively, P < 0.001. Except that the length, maximum diameter and volume of GTV in pathological T3 and T4 had no significant difference, other indicators of the pathological T stages showed significant differences between the groups (P < 0.001). According to the median volume of GTV at different pathological T stages, the GTV volumes were divided into three grades: <or= 5.0 cm(3), 5.1 - 13.0 cm(3), and > 13.0 cm(3). When compared them with pathological T1, T2, and T3-T4 stages, the coincidence rate was 73.8%. The consistency was good between the GTV volume grades and pathological T stages (Kappa = 0.40, P < 0.001). The overall 5-year survival rates of GTV grades 1, 2, 3 were 78.1%, 31.5% and 33.5%, respectively (P < 0.0001). If the GTVs were divided into four grades: <or= 5.0 cm(3), 5.1 - 13.0 cm(3), 13.1 - 39.0 cm(3), and > 39.0 cm(3), the coincidence rate of GTV volume grades and pathology T staging was only 54.7%, and the consistency was poor, Kappa = 0.24, P < 0.001. The overall 5-year survival rate of GTV 1, 2, 3, 4 were 78.1%, 31.5%, 36.2% and 27.5%, respectively (P < 0.0001).</p><p><b>CONCLUSION</b>The length, maximum diameter and volume of esophageal carcinoma GTV are related to pathological T staging with a positive correlation. The classification that esophageal carcinoma GTVs divided into three grades has a good coincidence with the pathological T staging.</p>