ABSTRACT
Objective:To obtain the inter-fractional set-up errors of intensity-modulated radiotherapy (IMRT) of cervical cancer by cone-beam CT (CBCT), and to analyze the variations of the set-up errors on the cumulative dose deviation of the target volume.Methods:A total of 48 patients with cervical cancer who underwent IMRT were enrolled in this study, and the set-up errors of 696 CBCTs were obtained. The set-up errors were input into the treatment planning system, and the cumulative set-up error dose was obtained by superposing the set-up errors dose. The deviation percentage was calculated by the deviation formula and the standard planning dose.Results:The set-up errors caused the offset of isocenter distance by 0.58(0.36, 0.80) cm. Different statistical differences were noted between the cumulative set-up error dose and the standard planning dose by WilCoxon test. All the dose deviations in the target volume were reduced, and the differential dose volume histogram (DVH) appeared negatively skewed, and the peak value was declined. The DVH diagram shifted to the left with an inverse S-curve and the slope was increased. The HI deviation of the target volume from small to large were: CTV 1, CTV 2, GTV/CTV, CTV 3, CTV n, CTV all, and GTV nd; The HI deviation of the target volume were increased. Conclusions:The effect of set-up errors in IMRT of cervical cancer upon the cumulative doses of the target volume significantly differs. The cumulative dose of the target volume is reduced, and the uniformity of the target volume dose becomes worse. The uncertainty of the inter-fractional position leads to an increase or decrease in the the fractional doses of the target volume. The biological effect on tumor cells and the tumor recurrence remains to be investigated. In IMRT of cervical cancer, the CBCT position calibration is required before each treatment to ensure the dose accuracy of each structure in the target volume.
ABSTRACT
Objective To investigate the clinical outcomes of patients with locally advanced uterine cervical cancer (UCC) treated by 3-dimensional high dose rate-intracavitary brachytherapy (3D HDR-ICBT) combined with complementary applicator-guided external beam radiotherapy (EBRT).Methods A total of 120 patients pathologically diagnosed with locally advanced UCC (tumors with a maximum diameter≥6 cm or ≥5 cm complicated with eccentric tumor growth) treated with concurrent chemoradiotherapy (CCRT) from June 2010 to June 2015 were recruited.Five fractions of 3D HDR-ICBT combined with complementary applicator-guided external beam radiotherapy were performed.The prescribed dose for HR-CTV and IR-CTV was 7 Gy (D9o) and 5-6 Gy (D90).The rectum,sigmoid colon,bladder and adjacent small intestine were delineated as the organs at risk.Intensity-modulated radiation therapy (IMRT) was used for EBRT (45 Gy/ 25f) combined with cisplatin-based chemotherapy every three weeks (75 mg/m2).Results The median follow-up time was 46 months (14-96 months).The 5-year local control rate (LCR),disease-free survival (DFS),and overall survival (OS) were 92.8％,76.6％ and 81.0％,respectively.The incidence rate of grade Ⅰ-Ⅱ genitourinary and gastrointestinal acute toxicities were 57.8％ and 14.6％,whereas 8.1％ and 2.9％ for grade Ⅲ toxicities.The incidence rate of later grade Ⅰ-Ⅱ genitourinary and gastrointestinal toxicities were 8.4％ and 5.3％,and 0.97％ and 1.3％ for grade Ⅲ late toxicities.Conclusions The combination of HDR-ICBT with an applicator-guided IMRT (ICBT+IMRT) yields low incidence of severe adverse events,relatively high LC and OS rate for locally advanced UCC.It is an efficacious comprehensive treatment of locally advanced bulky UCC.
ABSTRACT
Objective Bladder filling in patients with cervical cancer before and after operation during intensity-modulated radiotherapy (IMRT) was controlled by using bladder volume measurement instrument (BVI 9400).The displacement errors of the target area and the changes of the irradiation dose and the morphology of the filling bladder were compared.The significance of consistency of preoperative and postoperative bladder filling in IMRT for cervical cancer was investigated.Methods Forty-five patients with cervical cancer treated with radiotherapy in our hospital in 2018 were recruited and divided into A,B and C groups (n=15).In group A,patients did not undergo surgery,patients in group B received radical resection of cervical cancer (bladder volume measurement (BVI 9400) was utilized to monitor the bladder urine volume in both A and B groups before treatment).In group C,patients who self-controlled urination without monitoring bladder urine volume before treatment were randomly selected.All patients in three groups underwent KV-CBCT scan before treatment for online registration analysis.The displacement errors in the x-(left and right),y-(head and foot),z-axis directions (ventral and dorsal),PTV coverage volume percentage (V10o) and percentage difference (△ V100) of the prescription dose were calculated.Results The average displacement errors in the x-,y-,z-axis directions were as follows:1.67 mm,1.55 mm and 1.67 mm in group A,1.43 mm,1.58 mm and 1.84 mm in group B,and 2.27 mm,2.30 mm and 2.08 mm in group C,respectively.In group A,the V1oo was calculated as 96.96％ and △ V1oo was 1.17％.In group B,V1oo was 9 5.9 ％ and △ V10o was 1.2 9 ％.In group C,V10o was 9 4.0 2 ％ and △ V100 was 2.1 7 ％.Conclusions Controlling the consistency of bladder filling can reduce the effect of inconsistency of bladder filling upon the displacement errors to certain extent,which can guarantee the accuracy of the target location and the irradiation dose of the target,protect the bladder,small intestine and rectum,and alleviate the radiation-induced response of cervical cancer patients.
ABSTRACT
Brachytherapy is a key part of radical radiotherapy for cervical cancer. Along with the persistent development of radiotherapy techniques, the combined application of brachytherapy and intensity-modulated radiotherapy ( IMRT) has been proposed by scholars for cervical cancer patients presenting with large residual tumors accompanied by parametrial infiltration after IMRT. In this article, recent research progress on IMRT combined with brachytherapy applied in the treatment of cervical cancer was reviewed.
ABSTRACT
Objective To compare the differences of gross tumor volume (GTV) and dose distribution between MRI-CT fusion imaging and CT-based imaging and investigate the dose difference in the therapeutic regime.Methods Ten patients diagnosed with primary tumors of the cervical vertebra between 2013 and 2014 were enrolled.Prior to radiotherapy,the imaging data of MRI examination (GE Discovery MR 750 3.0T) were collected,transfered into the Eclipse system and subject to fusion with CT images.GTV delineation,organ at risk (OAR) delineation and dose distribution discrepancy induced by target volume differences were analyzed and statistically compared between the MRI-CT fusion and CT-based images.GTV delineation and dose parameters among different radiologists between two approches were analyzed by analysis of variance (ANOVA) and paired t-test.Non-normally distributed variables were analyzed by Wilcoxon rank-sum test.The reliability of intraclass correlation coefficient (ICC) was assessed.Results The GTVMRI-CT volume was larger compared with the GTVCT volume.The volume overlap index was 0.84±0.17.The cordMRI-CT volume was significantly less than the cordCT volume (P=0.001).For 5 radiologists,the ICCMRI-CT was larger than ICCCT.The DmaxMRI-CT of the spinal cord was (46.00± 1.09) Gy,significantly less than (52.39±1.34) Gy for the DmaxCT(P=0.014).Conclusions It is unlikely to miss the target delineation on MRI-CT fusion imaging.MRI-CT fusion imaging can minimize the discrepancy of interobserver radiologists and cause dosimetric advantages.