The value of systematic contouring of the bowel for treatment plan optimization in image-guided cervical cancer high-dose-rate brachytherapy (original) (raw)
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Journal of Contemporary Brachytherapy
Purpose: Brachytherapy (BRT) is a cornerstone in cervical cancer treatment, with the ultimate goal to maximize the tumor dose while sparing organs at risk (OARs), such as rectum. Several studies evaluated the effect of rectal volume on rectal doses, but the results are inconsistent. This study aimed to evaluate the rectal volume and dose-volume histogram (DVH) relationship in high-dose-rate (HDR) brachytherapy in locally advanced cervical cancer. Material and methods: Planning computed tomography of 65 patients who underwent HDR brachytherapy boost as a component of definitive radiotherapy from March 2016 to February 2018 were reviewed. OARs and target volume were re-delineated by a single physician to decrease interobserver variation. Two sets of plan were generated; in the first set, the dose was prescribed to point A with Manchester system loading pattern, while in the second set, the dose was prescribed to high-risk clinical target volume (HR-CTV) D 90 with inverse planning optimization. The DVH values for rectum, sigmoid, and HR-CTV were generated and correlated with rectal or sigmoidal volume variation. Results: Dose to 2cc (D 2cc), 1cc (D 1cc), and 0.1cc (D 0.1cc) of rectum and sigmoid showed a significant decrease in optimization vs. point A planning (p < 0.0001). HR-CTV D 90 coverage was significantly higher in optimization vs. point A planning (p = 0.041). Rectal volume showed a significant correlation with D 2cc (rs, 0.302, p = 0.014), D 1cc (rs, 0.310, p = 0.012), and D 0.1cc (rs, 0.283, p = 0.02) of rectum in optimization planning. Conclusions: Larger rectal volumes are associated with higher rectal dose parameters during HDR brachytherapy using inverse planning optimization. This method spares OAR, while producing reasonable HR-CTV D 90. Prospective studies are needed to find appropriate technique of rectal volume reduction.
Radiotherapy and Oncology, 2015
To establish dose-volume effect correlations for late bladder and rectum side effects in patients treated for locally advanced cervical cancer with concomitant chemoradiation followed by pulsed-dose rate image-guided adaptive brachytherapy. Material and methods: The dosimetric data, converted in 2 Gy equivalent, from 217 patients were confronted to late morbidity defined as any event lasting or occurring 90 days after treatment initiation. Toxicity was assessed using the CTC-AE 3.0. Probit analyses and Log rank tests were performed to assess relationships. Results: One hundred and sixty-one urinary and 58 rectal events were reported, affecting 98 (45.1%) and 51 (23.5%) patients, respectively. Cumulative incidences for grade 2-4 bladder and rectal morbidity were 24.3% and 9.6% at 3 years, respectively. Significant relationships were observed between grade 2-4 and 3-4 events and D0.1 cm 3 and D2 cm 3 for the bladder and between grade 1-4 and 2-4 event probability and rectal D2 cm 3. The effective doses for 10% grade 2-4 morbidity were 65.3 Gy (59.8-81.3), and 55.4 Gy (15.7-63.6), respectively, for the rectum and bladder. Without considering urinary and rectal incontinence, for which the pertinence of correlating them with D2 cm 3 is questionable, ED10 were 68.5 Gy (62.9-110.6) and 65.5 Gy (51.4-71.6 Gy). When sorting patients according to D2 cm 3 levels, patients with high D2 cm 3 had significantly lower morbidity free survival rates for grade 1-4 and 2-4 urinary and rectal morbidity. Conclusion: Significant dose-volume effect relationships were demonstrated between the modern dosimetric parameters and the occurrence of late rectal and urinary morbidity in patients treated with pulsed-dose-rate brachytherapy. Further studies are required to refine these relationships according to clinical cofactors, such as comorbidities.
Cancer radiothérapie : journal de la Société française de radiothérapie oncologique, 2014
The implementation of image-guided brachytherapy in cervical cancer raises the problem of adapting the experience acquired with 2D brachytherapy to this technique. The GEC-ESTRO (Groupe européen de curiethérapie - European Society for Radiotherapy and Oncology) has recommended reporting the dose delivered to the rectum in the maximally exposed 2 cm(3) volume, but so far, the recommended dose constraints still rely on 2D data. The aim of this study was to evaluate the relationship between the doses evaluated at the ICRU rectal point and modern dosimetric parameters. For each patient, dosimetric parameters were generated prospectively at the time of dosimetry and were reported. For analysis, they were converted in 2 Gy equivalent doses using an α/β ratio of 3 with a half-time of repair of 1.5 hours. The dosimetric data from 229 consecutive patients treated for locally advanced cervical cancer was analyzed. The mean dose calculated at ICRU point (DICRU) was 55.75 Gy ± 4.15, while it wa...
2017
CT-imaging based planning in intracavitary brachytherapy allows optimization of the dose distribution by patient basis. In addition to classical used point dose, the dose-volume histogram (DVH) analysis enables further possibilities for prescribing and reporting the correct dose. A group of 18 patients were treated with 38 fractions using different applicators and CT-based treatment planning. Each application was analyzed in detail. The clinical target volumes were contoured and also the organs at risk. The dose administered to bladder and rectum was analyzed according to ICRU Reports 38 and dose-volume parameters (e.g. D2cc represents the minimal dose for the most irradiated 2 cm). The values of the doses were analyzed including the external beam radiotherapy. Total doses were biologically normalized to conventional 2 Gy fractions (α/β = 10 Gy for target and 3 Gy for organs at risk). Individual changes for active dwell positions and dwell weights are guided by a concept of DVH cons...
Asian Pacific Journal of Cancer Prevention, 2014
Background: Dosimetric comparison of two dimensional (2D) radiography and three-dimensional computed tomography (3D-CT) based dose distributions with high-dose-rate (HDR) intracavitry radiotherapy (ICRT) for carcinoma cervix, in terms of target coverage and doses to bladder and rectum. Materials and Methods: Sixty four sessions of HDR ICRT were performed in 22 patients. External beam radiotherapy to pelvis at a dose of 50 Gray in 27 fractions followed by HDR ICRT, 21 Grays to point A in 3 sessions, one week apart was planned. All patients underwent 2D-orthogonal and 3D-CT simulation for each session. Treatment plans were generated using 2D-orthogonal images and dose prescription was made at point A. 3D plans were generated using 3D-CT images after delineating target volume and organs at risk. Comparative evaluation of 2D and 3D treatment planning was made for each session in terms of target coverage (dose received by 90%, 95% and 100% of the target volume: D90, D95 and D100 respectively) and doses to bladder and rectum: ICRU-38 bladder and rectum point dose in 2D planning and dose to 0.1cc, 1cc, 2cc, 5cc, and 10cc of bladder and rectum in 3D planning. Results: Mean doses received by 100% and 90% of the target volume were 4.24±0.63 and 4.9±0.56 Gy respectively. Doses received by 0.1cc, 1cc and 2cc volume of bladder were 2.88±0.72, 2.5±0.65 and 2.2±0.57 times more than the ICRU bladder reference point. Similarly, doses received by 0.1cc, 1cc and 2cc of rectum were 1.80±0.5, 1.48±0.41 and 1.35±0.37 times higher than ICRU rectal reference point. Conclusions: Dosimetric comparative evaluation of 2D and 3D CT based treatment planning for the same brachytherapy session demonstrates underestimation of OAR doses and overestimation of target coverage in 2D treatment planning.
IIUM Medical Journal Malaysia
INTRODUCTION: This retrospective study aims to evaluate the doses of organs at risk (OARs) calculated by conventional two-dimensional (2-D) and three-dimensional (3-D) treatment planning techniques in hybrid high dose rate (HDR) brachytherapy for cervical cancer. MATERIALS AND METHODS: Data of five patients treated with combination of intracavitary and interstitial brachytherapy were used. For each implant, computed tomography (CT) images were obtained, and the clinical target volume and OARs were contoured on CT images. In 3-D planning, the volumes of OARs were derived from dose-volume histogram (DVH) on a dose volume of 2 cc for bladder, rectum, and sigmoid. The OARs defined in replanning for 2-D treatment were the ICRU-38 bladder (bICRU) and rectum (rICRU) points. Paired T-tests were used to analyse the radiation doses of bladder and rectum obtained from both techniques. RESULTS: The mean point doses evaluated via bICRU) and rICRU were 89.34 GyEQD2 and 75.92 GyEQD2, respectively....
Journal of Nuclear Medicine and Radiation Therapy, 2015
Purpose and Objective(s): To investigate the advantages of volumetric treatment planning in HDR brachytherapy for cervical carcinoma compared to standardized loading based on 2-D planning techniques. Materials and Methods: Our institution uses volume-based 3-D planning for each tandem and ovoid (T&O) insertion for HDR brachytherapy in the treatment of advanced cervical carcinoma. Here, we attempt to define the benefits of this approach. We re-planned 48 CT-based treatment plans on 12 patients (treated in our facility between February, 2009 and February, 2010) using a commonly used 2-D standard HDR loading of the T&O. All patients had received 4 fractions of 6.5 Gy or 5 fractions of 5.5 Gy to point H or A. The following organs at risk (OARs) were contoured: rectum, bladder, sigmoid, and small bowel. Our customized planning approach required the adjustment of source dwell times and positions to keep doses to the OARs below 80% of the prescription dose. The standardized HDR planning, however, bases the loading time on the length of the tandem. The dwell time for each tandem source position is the same. The dwell time multipliers for the ovoids were 0.33, 0.665 and 1.0, proportionate to the 2 cm, 4 cm, and 6 cm tandem length, respectively. The dose to the highest 2 cc (D 2cc) of the OARs were also determined and analyzed. Results: There was a marked change in the value and location of the D 2cc for all OARs from one HDR session to the next in both the standard and customized plans. When the data for the 48 plans were analyzed together, there were no significant differences between the customized plans and the standardized plans. However, when data for the individual plans were analyzed, 35% of the 2-D based plans did not meet our treatment planning objectives. Conclusion: Using customized plans for HDR T&O brachytherapy did not always reduce the doses to the rectum, bladder, sigmoid, and small bowels compared to the standardized plans. The dose to the small bowel could be up to 15% higher than the dose to point H or A in the standard plans indicating that customized plans may be superior to the standardized ones for the treatment of patients where this dose is critical.