Analysis of dose-effect relationship between DVH parameters and clinical prognosis of definitive radio(chemo)therapy combined with intracavitary/interstitial brachytherapy in patients with locally advanced cervical cancer: A single-center retrospective study

PurposeThe purpose of the study was to explore the dose-effect relationship between dose-volume histogram parameters and clinical prognosis of definitive radio(chemo)therapy followed by intracavitary/interstitial brachytherapy in locally advanced cervical cancer.Methods and MaterialsA retrospective analysis was performed on 110 patients with locally advanced cervical cancer who underwent external beam radiotherapy combined with intracavitary/interstitial brachytherapy with or without chemotherapy from July 2010 to September 2018. We reported D₁₀₀, D₉₈, and D₉₀ for high-risk clinical target volume (HR-CTV) and intermediate-risk clinical target volume, D_2cm³ for organs at risk. Multivariate Cox regression was used to screen independent factors. Dose-volume parameters screened by the Cox regression were incorporated into the probit model for investigating its relationship with survival.ResultsThe median followup time was 72.33 months. Multivariate Cox regression analysis showed that HR-CTV D₁₀₀, HR-CTV D₉₈, and HR-CTV D₉₀ were independent factors, affecting the 5-year overall survival (OS), cancer-specific survival (CSS), and local control (LC) rates. The probit model showed that HR-CTV D₉₈ had predictive values for the 5-year OS, CSS, and LC, and HR-CTV D₁₀₀ had predictive values for the 5-year OS, CSS, whereas HR-CTV D₉₀ had a predictive value only for the 5-year OS. The HR-CTV D₉₈ corresponding to OS _ED90, CSS _ED90, and LC _ED90 was 86.8, 85.6, and 78.6 Gy, respectively.ConclusionsA significant dependence of OS, CSS, and LC on D₉₈ for HR-CTV was found. When the long-term OS, CSS, and LC rate of the patient was >90%, HR-CTV D₉₈ > 86.8 Gy _EQD2, 85.6 Gy _EQD2, and 78.6 Gy _EQD2 were required.     

A dosimetric evaluation of using a single treatment plan for multiple treatment fractions within a given applicator insertion in gynecologic brachytherapy

PurposeTo evaluate the dosimetric impact of using one treatment plan for multiple fractions from a single tandem and ring applicator insertion of high-dose-rate brachytherapy for cervical cancer.Methods and MaterialsThirteen cervical cancer patients undergoing high-dose-rate brachytherapy were followed. Patients received the total dose from a single applicator insertion in two fractions, given with at least 6 hours apart within 24 hours. The treatment plan was based on a CT scan taken before the first treatment fraction. A second CT was obtained before the second treatment fraction. The co-registered image series were used to evaluate the dosimetric impact of using a single treatment plan for both fractions. Applicator and catheters were measured to quantify interfraction displacement.ResultsWhen the Day 1 plan was applied to the Day 2 images, high-risk clinical target volume (HR-CTV) coverage was reduced by as much as 17.4 percentage points. The mean decrease was 9.4 ± 5.0 percentage points (p < 0.0001). The rectum V₇₅ increase was significant (p = 0.03), whereas the bladder V₇₅ increase was not significant (p = 0.28). Volume changes in the HR-CTV contour from Day 1 to Day 2 were also observed (p = 0.29). Maximum applicator and catheter displacements of 10–30 mm were seen, from Day 1 to Day 2.ConclusionsWhen the Day 1 plan was used on the Day 2, the HR-CTV coverage decreased significantly (p < 0.0001). Our study establishes the need for institutions to evaluate the necessity for replanning based on imaging obtained before each treatment fraction for their gynecologic brachytherapy techniques.     

Comparative analysis of rectal dose parameters in image-guided high-dose-rate brachytherapy for cervical cancer with and without a rectal retractor

PurposeThe objective of this study was to determine if use of a rectal retractor (RR) in high-dose-rate intracavitary brachytherapy for cervical cancer reduces rectal dose parameters.Methods and MaterialsWe reviewed data obtained from patients treated with intracavitary brachytherapy for cervical cancer with and without an RR. Treatment plans for each brachytherapy fraction were separated into two groups; R group with use of an RR and P group with use of vaginal packing. Dose–volume parameters for high-risk clinical target volume (HR-CTV), rectum, sigmoid, small bowel, and vaginal surface were collected for each fraction. Rectal D_2cc and International Commission on Radiation Units & Measurements (ICRU) rectal point doses were compared between groups using Student's t tests. Predictors of higher rectal D_2cc were determined by univariate and multivariate regression analyses.ResultsFour hundred sixty-three brachytherapy fractions from 114 patients were used for analysis, 377 fractions with a RR (R group) and 86 with vaginal packing only (P group). Both groups were similar except for slightly higher mean HR-CTV and mean bladder volume in P group. Both mean ICRU rectal point dose (241.1 vs. 269.9 cGy, p = 0.006) and rectal D_2cc (240.6 vs. 283.6 cGy, p < 0.001) were significantly higher in P group. Point A dose, HR-CTV, stage, and use of an RR were significant predictors of rectal D_2cc on multivariate analysis.ConclusionsOur data show that use of an RR leads to lower rectal dose parameters compared with vaginal packing. Further study is needed to determine if this will lead to less long-term toxicity.     

3-T MRI-based adaptive brachytherapy for cervix cancer: Treatment technique and initial clinical outcomes

PurposeTo report the techniques and initial clinical outcomes for MRI-based adaptive brachytherapy (MRIB-ABT) using 3-T MRI.Methods and MaterialsAll patients who underwent MRIB-ABT between January 2008 and June 2012 for cervical cancer using 3-T MRI for at least three fractions were retrospectively reviewed. The institutional standard for initiation of brachytherapy planning was 100% of dose at point A and 160% at the vaginal surface with five fractions of 500–550 cGy at Point A. The dose distribution was modified to enhance coverage of the high-risk clinical target volume (HR-CTV) and to spare the organs at risk (OAR) by altering dose specification distances around the tandem and the percentage of the Point A dose around the ring or ovoids.ResultsEighteen patients (FIGO stages IB = 4, II = 12, III = 1, and IVA = 1) underwent eighty-two 3-T MRI-based insertions. All patients received 3D conformal, external beam radiation (45–50.4 Gy). The median gross tumor volume pretreatment was 38 cm³ (2–165 cm³) compared with 4.8 cm³ (1–9 cm³) at the first high–dose rate fraction with a median volume reduction of 88%. Dose specification at the level of Point A was altered in 51% of 3-T MRI fractions from the standard 20 mm (range, 14–18 mm) and in 8% at the ring surface to optimally cover the HR-CTV and spare the OAR. The 2-year local control, disease-specific survival, and overall survival are 100%, 100%, and 93%, respectively.ConclusionsMRIB-ABT using 3-T MRI for treatment of cervix cancer allows for customized alterations in dose specification that minimize dose to the OAR and maximize coverage of the HR-CTV.     

Early outcomes and impact of a hybrid IC/IS applicator for a new MRI-based cervical brachytherapy program

PurposeThe purpose of this study was to report early outcomes and assess the learning curve in a new MRI-based cervical brachytherapy program.MethodsWe accrued 33 patients prospectively, and only patients with ≥3 months' followup (n = 27) were assessed for disease control and toxicity. Eras were defined as first half and second half for the intracavitary (IC)-only era (n = 13 each), and the intracavitary/interstitial (IC/IS) era was separated by difference in applicator availability (n = 7). Dose to 90% of the high-risk clinical target volume (D₉₀ HR-CTV) and minimum dose to the maximally irradiated 2 cubic centimeters (D_2cc) to organs at risk were used to assess dosimetry. Statistics were performed with t tests and Kaplan–Meier method.ResultsMedian followup was 14.7 months. Median treatment duration was 50.5 vs. 57 days for patients treated with external beam radiation therapy at our institution vs. an outside institution (p = 0.03). One-year local control, noncervical pelvic control, distant metastasis–free rate, and overall survival were 84.0%, 96.0%, 78.5%, and 91.3%, respectively. When comparing the first half and second half eras of IC only, there were no differences in median D₉₀ HR-CTV or D_2cc of the bladder, rectum, or sigmoid. Comparing the entire IC era to the IC/IS era, median D₉₀ HR-CTV trended higher from 88.0 Gy to 92.9 Gy (p = 0.11). D_2cc rectum decreased from 69.3 Gy to 62.6 Gy (p = 0.01), and D_2cc bladder trended lower from 87.5 Gy to 83.6 Gy (p = 0.09).ConclusionsThere was no significant difference between the first half and second half eras with IC-only MRI-based brachytherapy. Incorporation of an IC/IS applicator generated the greatest dosimetric improvement. Early results of the MRI-based brachytherapy program are favorable.     

Comparison of computed tomography with magnetic resonance imaging for imaging-based clinical target volume contours in cervical cancer brachytherapy

PurposeTo compare CT- and MRI-based brachytherapy (BT) target volumes for patients with advanced cervical cancer so as to identify those who benefit most from MRI-based planning. We also studied how the natural mobility of the organ at risks (OARs) affects the given doses.Methods and MaterialsSubjects were 60 patients with International Federation of Gynecology and Obstetrics (FIGO) Stage IB–IVA cervical cancer. The CT high-risk clinical target volume (HR-CTV) was first delineated, then the MRI HR-CTV, with volume discrepancies calculated by subtraction. The DICE coefficient (DC) of similarity was calculated from a superimposition of the volumes. Maximum doses delivered to D_2cc of OARs in CT and MRI plans were compared; the effect of time on the natural mobility was analyzed.ResultsThe mean HR-CTVs and the maximum doses given to OARs in CT- and MRI-based planes were similar. Multivariate analysis showed that deep infiltration affecting the uterine corpus and bowel loops adjacent to the cervix were the factors significantly impacting on the volume discrepancy between CT and MRI HR-CTV (p = 0.001, p = 0.045) and on the DC (p = 0.005, p = 0.028). Univariate analysis demonstrated that the FIGO stage had a significant impact on DC (p = 0.022). Patients with bowel loops adjacent to the cervix had lower body mass indices (p = 0.003). The median difference between the doses given in CT- and MRI-based plans, caused by mobility, were 0.5 Gy, 0.3 Gy, and 0.45 Gy per fraction for the rectum, bladder and sigmoid, respectively. No correlation of observed uncertainties and time between image acquisitions was detected.ConclusionsCT- or MRI-based scans at BT are adequate for OAR dose–volume histograms analysis. Cervical cancer patients with deep infiltration affecting the uterine corpus, a low body mass index with bowel loops adjacent to the cervix and an FIGO Stage III–IVA benefit most from MRI-based planning of BT.     

Practically achievable maximum high-risk clinical target volume doses in MRI-guided intracavitary brachytherapy for cervical cancer: A planning study

PurposeTo explore maximum high-risk clinical target volume (HR-CTV) doses that can be practically achieved when organs at risk (OARs; bladder, rectum, and sigmoid) doses are allowed to equal current recommended thresholds in MRI-based intracavitary brachytherapy (BT) planning for cervical cancer.Methods and MaterialsPlanning MRI sets were retrieved for 21 patients who received pulsed-dose-rate BT boost. Plans were generated using manual optimization (MO) by adjusting dwell positions and times to obtain the prescribed HR-CTV isodose that includes 90% of target (D₉₀) coverage of 35 Gy while limiting OAR doses to below recommended tolerances (prescribed dose target [TGT] plans). Additional planning was performed with automatic volume optimization (VO) to evaluate target coverage relative to the MO plans. The MO and VO approaches were then applied with the objective of obtaining the highest possible HR-CTV coverage when OAR doses were allowed to equal threshold tolerance values (maximized [MAX] plans). A two-tailed paired t test was performed to determine the statistical significance of the results; significance level set at p < 0.013.ResultsMO and VO planning techniques could conform HR-CTV D₉₀ to the prescribed dose quite similarly for TGT plans. Using the MAX approach, the HR-CTV D₉₀ could be increased by 30% and 37% for MO and VO, respectively, without exceeding OAR thresholds. Sigmoid and often rectum were the dose-limiting structures during MAX planning.ConclusionsSimple differences in the approach to volumetric MRI-based cervix BT treatment planning can impact HR-CTV D₉₀. Consequently, dose escalation for MRI-guided cervix BT appears feasible in this manner should clinical circumstances warrant.     

Proof of principle: Applicator-guided stereotactic IMRT boost in combination with 3D MRI-based brachytherapy in locally advanced cervical cancer

PurposeTo describe a new technique involving high-precision stereotactic intensity-modulated radiation therapy (IMRT) boost in combination with intracavitary-interstitial (IC-IS) brachytherapy (BT) in cervical tumors that cannot be sufficiently covered by IC-IS-BT due to extensive residual disease and/or difficult topography at the time of BT.Methods and MaterialsThree patients with stage IIIB-IVA cervical cancer had significant residual disease at the time of BT. MRI-guided IC-IS-BT (pulsed-dose rate) was combined with a stereotactic IMRT boost guided according to the BT applicator in situ, using cone beam CT. The planning aim dose (total external beam radiotherapy and BT) for the high-risk clinical target volume (HR-CTV) was D90 >70–85 Gy, whereas constraints for organs at risk were D_2cm3 <70 Gy for rectum, sigmoid, and bowel and <90 Gy for bladder in terms of equivalent total dose in 2 Gy fractions. An IMRT boost adapted to the BT dose distribution was optimized to target the regions poorly covered by BT.ResultsHR-CTV doses of D90 >81 Gy were obtained in the central HR-CTV and D90 >69 Gy in the distal regions of HR-CTV. Image-guided set up of the IMRT boost with the applicator in situ was feasible. The dose plans were robust to intra-fraction uncertainties of 3 mm. Local control with acceptable morbidity was obtained at a followup of 3, 2.5, and 1 year, respectively.ConclusionsThe combination of MRI-guided BT with an applicator-guided stereotactic IMRT boost is feasible. This technique seems to be useful in the few cases where HR-CTV coverage cannot be obtained even with IS-IC-BT.     

Can we reduce dose to ureters as avoidance organs for MRI based brachytherapy for cervical cancer? A dosimetric feasibility study

BACKGROUND AND PURPOSEUreteral stenosis (US) is an underreported complication of brachytherapy (BT) for cervical cancer (CC), with limited data on toxicity risk reduction. A previous study demonstrated ureter EQD2 D0.1cc > 77 Gy correlated with US development. We sought to assess feasibility of this constraint while maintaining similar HR-CTV coverage.MATERIALS AND METHODSPatients with locally advanced CC treated with EBRT plus HDR MRI-based brachytherapy boost without hydronephrosis at diagnosis and with ureter dose EQD2 D0.1cc > 77 Gy were included. Replan was attempted to achieve HR-CTV D90 ≥ 80–85 Gy and ureter dose reduction. Ureter distance from lateral margin of HR-CTV and tandem was recorded. t-test was performed to compare ureteral dose and HR-CTV D90.RESULTsOf 25 patients were identified. Hundred percent received 45 Gy in 25 fractions to the pelvis ± paraaortic lymph nodes and 80% receiving median additional parametrial dose of 5.4 Gy. Replan meeting ureteral dose of ≤77 Gy was feasible in 18 of 25 patients, with a reduction in median ureter D0.1cc from 82.3 to 76.8 Gy (p < 0.001). Median HR-CTV D90 was similar (84.7 vs. 85.0 Gy). Replan achieved D0.1cc ≤77 Gy in 56% of patients who experienced US. All unilateral US cases occurred in the ureter closest to HR-CTV.CONCLUSIONSOptimization to reduce ureter dose to ≤77 Gy is feasible when ureters are visible and contoured. Ureters may be considered as potential OAR during MRI-based brachytherapy treatment. Reduced ring to tandem total reference air kerma (TRAK) ratio may provide an additional metric by which to lower US risk.     

3T multiparametric MRI–guided high-dose-rate combined intracavitary and interstitial adaptive brachytherapy for the treatment of cervical cancer with a novel split-ring applicator

PurposeTo evaluate the role of 3T-MRI–guided adaptive high-dose-rate (HDR) combined intracavitary and interstitial brachytherapy for cervical cancer using a novel intracavitary split-ring (ICSR) applicator adapter.Methods and MaterialsWe retrospectively reviewed all HDR brachytherapy cases from 2013 to 2015 using an ICSR applicator. Initial optimization was performed using 3T multiparametric MRI (mpMRI) series with an applicator in place. The mpMRI series were discretionarily acquired before subsequent fractions for possible target adaptation. When necessary, interstitial needles (ISNs) were inserted through a novel ICSR adapter or freehand. Dosimetric parameters, clinical outcomes, and toxicities were compared between groups.ResultsSeventeen patients were included, with a mean followup of 32 months. An mpMRI series preceded each initial fraction and 52.9% of patients underwent ≥1 additional pretreatment mpMRI. Among these subsequent fractions, the high-risk clinical target volume was reduced in 80% vs. 41% without pretreatment mpMRI. Five patients had ISN placement (seven insertions) to improve extracervical target coverage. Mean D₉₀ (Gy) per fraction to the high-risk clinical target volume and intermediate-risk clinical target volume with and without an ISN were 7.51 ± 1.07 vs. 6.14 ± 0.52 (p = 0.028) and 6.35 ± 0.75 vs. 5.21 ± 0.49 (p = 0.007), respectively. Mean fractional D_2cc (Gy) for organs at risk was comparable. No Grades 3–4 toxicity was reported. Disease-free survival and local control for the ICSR-ISN and ICSR-alone groups were 29.8 months/80.0% and 31.2 months/83.3%, respectively.ConclusionsThe mpMRI acquisition with ICSR applicator in place immediately before HDR brachytherapy for cervical cancer guided successful adaptive treatment optimization and delivery. Our initial experience with a novel interstitial adapter for the split-ring applicator demonstrated excellent target coverage without compromising organs at risk, resulting in good local control and disease-free survival.     

Evaluation of intrafraction motion of the organs at risk in image-based brachytherapy of cervical cancer

Purpose/IntroductionTo assess the variation in the doses received by the organs at risk (OARs) that can occur during treatment planning of cervical cancer by image-based brachytherapy.Methods and MaterialsAfter intracavitary application, two sets of images—CT and MRI—were obtained. The two sets of images were fused together with respect to the applicator. Contouring was done separately on CT and MR images. Dose received by the OARs on CT images with respect to the plans made on the MR images was estimated and compared with those on the MR images.ResultsAlthough there was always a difference between the dose received by the OARs based on the CT and MRI contours, it was not significant for the bladder and rectum; 2 cc doses differed by 0.49 Gy (±0.44) p = 0.28 for the bladder and 0.30 Gy (±0.29) p = 0.16 for the rectum. The 1 cc and 0.1 cc differences were also not significant. However for the sigmoid colon, there was significant intrafraction variation in the 2 cc doses 0.61 (±0.6) p = 0.001, 1 cc doses 0.73 (±0.67) Gy p = 0.00, and 0.1 cc dose 0.97 (±0.93) Gy p = 0.009.ConclusionsThe variation in the doses to the OARs must be considered while weighing target coverage against overdose to the OARs. Although not significant for the bladder and rectum, it was significant for the sigmoid colon. Estimated doses to OARs on the planning system may not be the same dose delivered at the time of treatment.     

Three-dimensional image-guided combined intracavitary and interstitial high-dose-rate brachytherapy in cervical cancer: A systematic review

PurposeTo evaluate the local control and toxicities of three-dimensional image-guided combined intracavitary and interstitial (IC/IS) high-dose-rate brachytherapy (BT) in cervical cancer through a systematic review.Methods and MaterialsA systematic review of relevant studies was performed through the PubMed, Web of Science, and Cochrane Library databases through May 10, 2020. Articles reporting on IC/IS technology, volumetric doses to high-risk clinical target volume (HR-CTV) and organs at risk (OARs), tumor control and/or treatment-related side effects were identified. The key information, including the type of applicator, implantation technology, characteristics of implantation, volumetric doses, tumor control, and/or treatment-related side effects, was extracted. A probit model analysis between HR-CTV D90 and tumor local control was performed.ResultsTwelve studies encompassing 520 patients were included in the probit model between HR-CTV D90 and the local control rate. The probit model showed a significant relationship between the HR-CTV D90 value and the local control probability, p = 0.003. The prescribed dose of 85 Gy_EQD2,10 would in theory warrant an 87.4% (95% confidence interval 82.5%–90.5%) local control rate.ConclusionIC/IS BT is an appropriate method to achieve a high therapeutic ratio for tumors with large volumes or poor responses after external irradiation in cervical cancer. The probit model showed that the dose escalation of HR-CTV D90 was helpful to improve the local tumor control rate.     

Dosimetric and clinical outcome in image-based high-dose-rate interstitial brachytherapy for anal cancer

PurposeTo evaluate dosimetric and clinical outcome in patients of anal cancer treated with image-based interstitial high-dose-rate brachytherapy following chemoradiation.Methods and MaterialsSixteen patients with anal cancer were treated with chemoradiation followed by brachytherapy boost with image-based high-dose-rate interstitial brachytherapy from January 2007 to June 2011. Two brachytherapy dose schedules were used: 21 Gy in seven fractions and 18 Gy in six fractions depending on response to chemoradiation. CT scan was done after placement of needles for confirmation of placement and treatment planning. Target volume was contoured on CT scans. Volumetric quality indices and dose parameters were calculated.ResultsThe mean clinical target volume was 17.7 ± 4.98 cm³, and the median overall tumor size was 4.2 cm (3.4–5 cm). The mean values of coverage index, dose homogeneity index, overdose volume index, dose non-uniformity ratio, and conformal index were 0.94, 0.83, 0.21, 0.37, and 0.88, respectively. With a median followup of 41 months (range, 20–67.2 months), preservation of the anal sphincter was achieved in 14 patients. The 1- and 2-year local control rates were 93.8% and 87.5%, respectively. Treatment was well tolerated and none of the patients developed Grade 3 or higher late toxicity.ConclusionsThe combination of external beam radiotherapy with interstitial brachytherapy increases the dose to the tumor volume and limits the volume of irradiated normal tissue, thereby decreasing late toxicity. The use of image-based treatment planning provides better dose conformality with reduced toxicity and helps to prevent a geographic miss.     

Benefit of adaptive CT-based treatment planning in high-dose-rate endorectal brachytherapy for rectal cancer

PurposeIn this planning study, we investigated the dosimetric benefit of repeat CT-based treatment planning at each fraction vs. the use of a single CT-based treatment plan for all fractions for high-dose-rate endorectal brachytherapy (HDREBT) for rectal cancer.Methods and MaterialsWe included 11 patients that received a CT scan with applicator in situ for all three fractions. The treatment plan of the first fraction was projected on the repeat CT scans to simulate the use of a single treatment plan. In addition, replanning was performed on the repeat CT scans, and these were compared to the corresponding projected treatment plans.ResultsRepeat CT-based treatment planning resulted on average in a 21% higher (p = 0.01) conformity index compared to single CT-based treatment planning. Projecting the initial treatment plan to the repeat CT scans of fraction two and three, 12/22 fractions reached a CTV D98 of 85% of the prescribed dose of 7 Gy, which increased to 14/22 using replanning. For the remaining fractions, median CTV D98 was 4.2 Gy, and an intervention would be necessary to correct applicator balloon setup or to remove remaining air and/or feces between the CTV and the applicator.ConclusionsUsing a single CT-based treatment plan for all fractions may result in a suboptimal treatment at later fractions. Therefore, repeat CT imaging should be the minimal standard practice in HDREBT for rectal cancer to determine whether an intervention would be necessary. Replanning based on repeat CT imaging resulted in more conformal treatment plans and is therefore recommended.     

Combined intracavitary and interstitial brachytherapy of cervical cancer using the novel hybrid applicator Venezia: Clinical feasibility and initial results

PurposeTo report on first-in-human experience and the initial clinical results using the hybrid applicator Venezia (Elekta, Sweden) in the treatment of patients with locally advanced cervical cancer.Material and MethodsBetween March, 2017, and February, 2018, a total of 40 fractions were performed on patients undergoing definitive chemoradiation and brachytherapy (BT) for cervical cancer. A plan comparison was conducted evaluating the hybrid applicator with the clinically used intracavitary and interstitial (IC/IS) BT against a standard plan prescribed to Point A and a manually optimized plan using only intracavitary (IC) BT. Overall 80 treatment plans were retrospectively generated.ResultsThe clinical use of the hybrid applicator system proved to be feasible in all 40 treatment fractions. The applicator consists of the IC tandem and two lunar-shaped ovoids forming a ring that serves as a template for defined parallel and oblique (12°) needle insertion. MRI preplanning was performed the day before the implant. One to six needles were placed per fraction, and overall a total of 66 needles were used. No complications such as bleeding or organ penetration occurred due to needle placement. Significant differences in IC/IS, Point A, and IC plans were derived for dose application to the target volume; D₉₀ high-risk clinical target volume was 90.7 vs. 88.1 vs. 80.8 Gy (p = 0.008). Likewise, sparing of organs at risk differed significantly for bladder D_2cc 79.4 vs. 91.8 vs. 79.2 Gy (p = 0.03) and rectum D_2cc 58.7 vs. 67.3 vs. 62.5 Gy (p = 0.03).ConclusionThe clinical application of the Venezia applicator is feasible and allows significantly improved dose coverage while at the same time sufficiently sparing organs at risk.     

3D打印模板应用于局部晚期宫颈癌后装放疗的剂量学研究

目的 局部晚期宫颈癌后装放疗应用3D打印微创导向模板的剂量学研究。方法 本研究为前瞻性研究,选取2016年5月-2019年8月就诊河北省沧州中西医结合医院的局部晚期宫颈癌患者共68例,均为偏心性或外照射后仍有巨大肿块（肿瘤直径>5 cm）残存的患者,外照射采用调强放疗,后装治疗方法为腔内联合组织间插植放疗,高危临床靶区（high-risk clinical target area,HR-CTV）剂量为6 Gy/次,1次/周,共5次。68例患者采用随机数表法分为两组,其中模板组35例采用3D打印微创导向模板辅助置入宫腔管并植入插植针;自由插植组33例徒手进行宫腔管的置入及插植针的植入。所有患者均于CT引导下调整宫腔管、插植针位置及深度,将最终CT图像传入后装治疗计划系统,勾画靶区及危及器官,制定治疗计划,实施治疗。结果 共制定340次后装放疗计划,其中模板组175次、自由插植组165次。模板组较自由插植组的HR-CTV的D₉₀（包绕90%靶区体积的剂量）、中危临床靶区（intermediate-risk clinical target volume,IR-CTV）的D₉₀均明显增高（t=3.63、2.45,P<0.05）,膀胱、直肠及乙状结肠的D_{2 cm³}均显著降低（t=-2.81、-2.54、-2.33,P<0.05）。同时,模板组每次后装治疗平均扫描CT次数为（1.78±0.53）次,每次治疗从宫腔管及插植针植入至调整达满意位置的平均消耗时间为（11.35±3.98）min,每次治疗使用插植针的针数平均为（5.21±1.37）枚。而自由插植组分别为（3.56±0.88）次,（30.67±5.83）min,（7.48±2.79）枚,两组比较差异均具有统计学意义（t=-2.26、-4.53、-3.21,P<0.05）。结论 对于偏心性或巨大肿块的局部晚期宫颈癌患者,腔内联合组织间插植治疗应用3D打印微创导向模板剂量学优势明显,操作简便,用时短。     

Image-guided brachytherapy following external-beam radiation therapy for patients with inoperable endometrial cancer

ObjectiveTo investigate the outcomes of definitive external-beam radiation therapy (EBRT) plus image-guided brachytherapy (IGBT) in patients with endometrial cancer (EC) unsuitable for surgery.MethodsA total of 50 patients with inoperable EC were included. The patients received EBRT in a median dose of 45 Gy to the pelvis over 5 weeks. Thereafter, the patients received brachytherapy using tandem and ovoid applicators. High-risk clinical target volume (HR-CTV) and gross tumor volume in brachytherapy (GTVp) were defined by the assistance of patients’ pre-IGBT magnetic resonance imaging.ResultsThe medical records of the 50 patients were analyzed. The main causes of inoperability were anesthesia contraindications, namely medical comorbidities and obesity. The median cumulative D90s (the minimum dose delivered to 90% of the volume) in EQD2 (equivalent dose in 2-Gy fractions) to the HR-CTV and GTVp were 72.9 Gy10 (range, 64.9 to 80.3) and 166.2 Gy10 (range, 123.0 to 189.8), respectively. Over a median follow-up period of 27 months, 8 of the patients died of cancer. The 2-year overall and cancer-specific survival rates were 75% and 83%, respectively. The cumulative incidences of pelvic and distant failure were 4% (n = 2) and 16% (n = 8), respectively. Gastrointestinal complications of grade 2 or above were noted in 2 patients (4%), and a grade 2 genitourinary complication was noted in one.ConclusionsFor patients with inoperable EC, EBRT followed by IGBT is an effective approach for achieving high local control without a high risk of complications.     

Clinical outcomes of high-dose-rate interstitial gynecologic brachytherapy using real-time CT guidance

PurposeTo evaluate clinical outcomes of CT-guided high-dose-rate (HDR) interstitial brachytherapy for primary and recurrent gynecologic cancer.Methods and MaterialsRecords were reviewed for 68 women (34 with primary disease and 34 with recurrence) treated with CT-guided HDR interstitial brachytherapy between May 2005 and September 2011. Interstitial application was performed under general anesthesia using an iterative approach of catheter insertion and adjustment with serial image acquisition by CT in a dedicated brachytherapy suite. The median fractional brachytherapy dose was 3.9 Gy delivered twice daily in seven fractions. The median cumulative dose in equivalent 2-Gy fractions was 74.8 Gy. Actuarial survival estimates were calculated using the Kaplan–Meier method, and toxicity was reported by Common Toxicity Criteria.ResultsPrimary disease sites were endometrial (34), cervical (17), vaginal (11), ovarian (3), and vulvar (3). Median age was 61.5 years, and tumor size at diagnosis was 3.4 cm. Median D₉₀ and V₁₀₀ were 73.6 Gy and 87.5%, respectively; median D_2cc for bladder, rectum, and sigmoid were 67.1, 64.6, and 53.7 Gy, respectively. With a median followup of 17 months, actuarial rates of local control, progression-free survival, and overall survival at 2 years for all patients were 86%, 60%, and 64%, respectively. There were 9 grade 3 late toxicities (six gastrointestinal and three vulvovaginal).ConclusionsHDR interstitial brachytherapy with CT-guided catheter placement results in acceptable local control, toxicity, and survival rates for women with primary or recurrent gynecologic cancer. Durable pelvic control may be achieved in most patients with this specialized brachytherapy technique.