Résumé
Objective:To identify dose-volume parameters to predict the incidence of acute intestinal toxicity in cervical cancer patients after postoperative adjuvant radiotherapy.Methods:Clinical data of 93 cervical cancer patients who underwent postoperative adjuvant intensity-modulated radiotherapy (IMRT) were retrospectively evaluated. The dose-volume parameters comprised the absolute volume of the bowel receiving 5-45 Gy (5 Gy interval) radiation dose and the total volume of the bowel. The acute radiation-induced intestinal toxicity was evaluated by Radiation Therapy Oncology Group (RTOG) criteria. The association between the irradiated bowel volume and acute intestinal toxicity was analyzed.Results:A total of 26 (28%) patients experienced grade ≥2 acute intestinal toxicity. A strong relationship between grade ≥2 acute intestinal toxicity and the irradiated small bowel volume was observed at the total volume of small bowel, small bowel V 5 Gy, V 10 Gy and V 15 Gy (all P<0.05). Small bowel V 10 Gy ( HR=1.028, 95% CI, 0.993-1.062, P=0.029) and small bowel ?V 15 Gy( HR=0.991, 95% CI, 0.969-1.013, P=0.034)were the independent risk factors for evident acute intestinal toxicity. Conclusion:Dose-volume parameters of the small bowel can be used as predictors for the occurrence of grade ≥2 acute intestinal toxicity in cervical cancer patients undergoing postoperative adjuvant radiotherapy.
Résumé
Objective:To analyze the local recurrence patterns after concurrent chemoradiotherapy (CCRT) for thoracic esophageal squamous cell carcinoma (ESCC) through image fusion, and to explore the risk factors of local recurrence and its relationships with dosimetric indices.Methods:A retrospective analysis was conducted for 209 thoracic ESCC patients who received radical CCRT in Fourth Hospital of Hebei Medical University during 2016-2019. For the patients diagnosed as the local recurrence of esophageal lesions, their CT images were fused with the original planning CT images using image registration software to identify the recurrence sites. Through 1∶1 propensity score matching (PSM) of the clinal data of patients with local recurrence (the recurrence group, nbefore = 81, nafter = 62) and those without local recurrence (the recurrence-free group, nbefore = 128, nafter=62), the dose and volume parameters of the treatment plans for the two groups were compared. Univariate and multivariate analyses were conducted using the Kaplan-Meier method and the Cox regression model to analyze the factors affecting the overall survival (OS), progression-free survival (PFS), and recurrence-free survival (RFS). Results:All patients had 1-, 3-, and 5-year OS rates of 80.9%, 42.6%, and 33.0%, respectively, 1-, 3-, and 5-year PFS rates of 67.9%, 34.0%, and 27.9%, respectively, and 1-, 3-, and 5-year RFS rates of 71.3%, 39.2%, and 30.5%, respectively. T stage, N stage, and radiation dose were independent prognostic factors for the OS, PFS, and RFS ( HR = 1.42-1.87, P < 0.05) of the patients, respectively. Among 68 patients with local recurrence, 62 cases (91.2%) suffered recurrence within the gross tumor volume (GTV). The dose and volume parameters of patients with local recurrence, such as GTV- D95%, clinical target volume (CTV)- D95%, GTV- D50%, CTV- D50%, and planning target volume (PTV)- D50%, GTV- V60, CTV- V60, and PTV- V60, were significantly lower than those of patients free from the local recurrence ( t=1.90-2.15, P < 0.05). Conclusions:Local recurrence of patients with thoracic ESCC after radical CCRT occurs mainly within the GTV. Increasing radiation doses may contribute to their survival benefits. The D50% for each target volume in the radiotherapy plan may be related to local recurrence, and it is necessary to conduct further research.
Résumé
Objective To analyze the correlation between ≥grade 2 radiation pneumonitis (RP) and dose volume parameters of elderly patients with esophageal cancer after three-dimensional conformal radiotherapy. Methods We collected the data of 250 elderly patients with esophageal cancer who received three-dimensional conformal radiotherapy from different medical centers. The clinical features of patients were analyzed by Chi-square test while dose volume parameters were analyzed by Logistic univariate and multivariate analyses. ROC curve was used to determine the best cut-off value. Results After three-dimensional conformal radiotherapy, 20% of patients developed ≥grade 2 RP. Univariate analysis showed that bilateral pulmonary V5, V10, V20, V30 and mean lung dose were associated with ≥grade 2 RP but multivariate analysis revealed that only V5 and V20 were independent relevant factors of RP. ROC curve indicated that the best cut-off value was V5 < 52.9% and V20 < 23.2%. Conclusion Bilateral pulmonary V5 and V20 are independently related to ≥grade 2 RP in elderly patients with esophageal cancer after 3-D conformal radiotherapy.
Résumé
Objective To identify the dose-volumetric parameters associated with acute bone marrow suppression in concurrent chemoradiotherapy for cervical cancer,and provide the reference standard for the radiotherapy planning.Methods In total,155 patients concurrently receiving chemoradiotherapy for cervical cancer were enrolled in this study.The pelvis was contoured for each patient in radiotherapy treatment planning system and divided into three subsites:lumbosacral spine,ilium,and lower pelvis.The pelvic dose volume parameters were analyzed using univariate analysis (Chi-Square and t test),and multivariate analysis (Logistic regression model).Dose volume parameters include V5,V10,V15,V20,V25,V30,V35,V40,V45,V50 and the average dose (D).Results The percentage of patients that developed acute bone marrow suppression (≥ grade 2) was 87.7％ (136/155).The univariate analysis revealed that pelvic V5,V10,V15,V,0,ilium V15,lower pelvis V15 of patients with acute bone marrow suppression (≥ grade 2) were significantly higher than those of ＜ grade 2 patients (t =-2.277,-2.142,-3.475,-2.018,-2.963,-2.741,P ＜0.05).Multiple regression analysis indicated that pelvic V15 was associated with acute bone marrow suppression (OR =1.728.P ＜ 0.05).The threshold of pelvic V15 was 88％ as determined by receiver operating curve (ROC).Conclusions The results show that Pelvic V15 is associated with acute bone marrow suppression in concurrent chemoradiotherapy for cervical cancer and is thus an independent risk factor.To better predict and control acute bone marrow suppression,pelvic V15 should be carefully controlled below 88％ in treatment planning to reduce the incidence of acute bone marrow suppression.
Résumé
Objective To evaluate the feasibility and significance of CT image-based threedimensional (3D) brachytherapy for cervical cancer.Methods Three-dimensional (3D) plan and twodimensional (2D) plan were designed for 55 CT images of brachytherapy from 12 cervical cancer patients who received radical radiotherapy in 2013.Dosimetric comparison was performed between the 3D plan and 2D plan,and paired t-test,Wilcoxon signed rank test,Pearson correlation analysis,and Spearman correlation analysis were performed.Results A point dose,D90,V100,CI,and CI' in 3D plan were higher than those in 2D plan (P=0.015,0.016,0.000,0.000,0.000).Bladder point dose,rectal point dose,and rectal D2 cm3 in 3D plan were slightly higher than those in 2D plan,but hot spot dose was significantly reduced in 3D plan (P =0.140,0.123,0.214).Bladder D2cm3 was significantly higher than bladder point dose (P =0.000).Sigmoid colon D2cm3 was more correlated with the average doses of the three highest rectal points than rectal D2 cm3 (r =0.314,0.630,P =0.000,0.000).V100 showed a linear relationship with high-risk CTV (r =0.981,P =0.000).Bladder D2cm3 was higher than 430 cGy when the bladder volume was more than 80 cm3 ;small intestinal D2 cm3 did not change significantly when the bladder volume was less than 115 cm3,but decreased significantly once the volume exceeded the value.Conclusions Compared with the traditional 2D plan,the 3D plan for CT image-based cervical cancer brachytherapy significantly increases the target coverage and conformity index,but does not significantly increase the doses to organs at risk.Point dose evaluation is confirmed to be inaccurate.The doses to the bladder,rectum,and small intestine can be adjusted by controlling the bladder volume.
Résumé
Objective To compare and analyze DMLC(Sliding Window,SW)and SMLC(Step and Shoot,SS)for delivering IMRT.Methods 5 patients with nasopharyngeal carcinoma were treated with radical intensity modulated radiation therapy using Varian 23EX and Helios tool on a Varian Eclipse system.Different modalities to deliver IMRT were considered for Sliding Window(SW) and Step and Shoot(SS) techniques using a different number of intensity levels(e.g.5,10 and 20).The total beam-on-time,total delivery time and a number of dose-volume parameters regarding PTV and OARs were considered.Results Comparing with the DVH,it was found that SW was the best of the four modalities in the dose distribution of PTV,but SS was better when considering the protection of OARs.The total beam-on-time(MUs) requirement for SS was 9～23% less than SW,but the total delivery time(in minutes)was about twice as long.Conclusion With the number of intensity level of 10 or more,no differences between SS and SW can be appreciated in the dose distribution of PTV and OARs sparing.Referring to the quality assurance,only leaf position needed to be checked in SS,whereas both leaf position and leaf speed need to be checked in SW,so it is proposed to use SS10 for delivering IMRT.