Point A vs. HR-CTV D90 in MRI-based cervical brachytherapy of small and large lesions (original) (raw)
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Toxicities and dose-volume histogram parameters of MRI-based brachytherapy for cervical cancer
Brachytherapy
To analyze the toxicities and dose-volume histogram parameters of external-beam and magnetic resonance imaging-based intracavitary brachytherapy in cervical cancer patients. Acute and late toxicities were assessed in 135 patients divided into four groups: group 1, grade 0; group 2, grades 1-4; group 3, grades 0-1; and group 4, grades 2-4. The doses at the International Commission on Radiation Units and Measurements (DICRU) and minimum doses to the most exposed 0.1, 1, 2, and 5 cc (D0.1cc, D1cc, D2cc, and D5cc) of normal organs were calculated as equivalent doses in 2 Gy (α/β = 3). The median follow-up was 35.2 months. For rectum, DICRU, D0.1cc, D1cc, and D2cc were significantly different between groups 1 and 2 and DICRU, D0.1cc, and D1cc between groups 3 and 4. For bladder, D0.1cc, D1cc, and D2cc were significantly different between groups 1 and 2 and DICRU, D1cc, D2cc, and D5cc between groups 3 and 4. Grade 2-4 bladder toxicity occurred in fewer patients with D2cc ≤ 95 Gy than thos...
Journal of Contemporary Brachytherapy
Purpose: The dose distributions obtained from three imaging approaches for target delineation in cervical cancer using high-dose-rate (HDR) brachytherapy were investigated. Material and methods: Ten cervical cancer patients receiving four fractions of HDR brachytherapy were enrolled. Based on different imaging approaches, three brachytherapy plans were developed for each patient: with the high-risk clinical target volume (HRCTV) delineated on magnetic resonance (MRI) images for every fraction (approach A; MRIonly); on MRI for the first fraction and computed tomography (CT) images for the subsequent fractions (approach B; MRI 1st /CT); and on CT images for all fractions (approach C; CT-only). The volume, height, width at point A, width at maximum level, and dosimetric parameters (D 100 , D 98 , D 95 , and D 90 of the HRCTV; and D 0.1cc , D 1cc , and D 2cc of all organs at risk, or organ at risk-OAR: bladder, rectum, sigmoid colon, and bowel) provided by each approach were compared. Results: The mean HRCTV volume, width, and height obtained from approach C (CT-only) were overestimated compared to those from approaches A (MRI-only) and B (MRI 1st /CT). The doses to the HRCTV for approaches A and B were similar. However, the HRCTV doses for approach C were significantly lower than those for approaches A and B for all parameters (D 95-D 100). As to the OAR, the three approaches showed no differences. Conclusions: A combination of MRI and CT is a safe alternative approach for cervical cancer HDR brachytherapy. The technique provides comparable dosimetric outcomes to MRI-based planning, while being more cost-effective.
International Journal of Radiation Oncology*Biology*Physics, 2014
Purpose/Objective-To create and compare consensus clinical target volume (CTV) contours for computed tomography (CT) and 3 Tesla (3T) magnetic resonance (MR) image-based cervicalcancer brachytherapy Materials/Methods-Twenty-three gynecologic radiation oncology experts contoured the same 3 cervical-cancer brachytherapy cases: one Stage IIB near-complete response (CR) case with a tandem and ovoid, one Stage IIB partial response (PR) case with ovoid with needles and one Stage IB2 CR case with a ring applicator. CT contours were completed before MRI contours. These were analyzed for consistency and clarity of target delineation using an expectation maximization algorithm for simultaneous truth and performance level estimation (STAPLE), with kappa statistics as a measure of agreement between participants. The conformity index (CI) was calculated for each of the six data sets. Dice coefficients were generated to compare CT and MR contours of the same case. Results-For all 3 cases, the mean tumor volume was smaller on MR than on CT (p<0.001). Kappa and CI estimates were slightly higher for CT, indicating a higher level of agreement on CT. DICE coefficients were 89% for the Stage IB2 case with a CR, 74% for the Stage IIB case with a PR, and 57% for the Stage IIB case with a CR. Conclusion-When comparing MR-to CT-contoured CTV volumes, the higher level of agreement on CT may be due to the more distinct contrast visible on the images at the time of brachytherapy. The largest difference at the time of brachytherapy was in the case with parametrial extension at diagnosis that had a near-complete response, due to the appearance of the parametria on CT but not on MR. Based on these results, a 95% consensus volume was generated for CT and for MR.
Brachytherapy, 2017
To evaluate the long-term disease control and toxicity to the organs at risk after dose-escalated image-based adaptive brachytherapy (BT) in cervical cancer. Sixty patients of cervical cancer were treated with external radiotherapy 46 Gy in 23 fractions with weekly cisplatin and MRI-guided BT 7 Gy × 4 fractions with a minimum dose of 85.7 Gy (EQD2) to the high-risk clinical target volume (HRCTV). The BT dose was initially prescribed to point A and plans were optimized to ensure coverage of both point A and HRCTV while maintaining doses to the organs at risk within the recommended constraints. Patients were followed up clinically every three months for the first two years and six months thereafter. Toxicity scoring for urinary and bowel symptoms was done using CTCAE version 3.0. The mean doses to the point A and D90 HRCTV were 85.5 (±2.75) Gy and 98.4 (±9.6) Gy EQD2 respectively. The mean 2 cc EQD2, the bladder, rectum, and sigmoid were 90.6 Gy, 70.2 Gy, and 74.2 Gy respectively. The...
CT or MRI for Image-based Brachytherapy in Cervical Cancer
Japanese Journal of Clinical Oncology, 2012
To compare volumes and doses of tumour and organs at risk with computed tomography vs. magnetic resonance imaging in cervical cancer brachytherapy. Methods: Seventeen previously untreated patients with cervical cancer suitable for radical treatment were included. All patients underwent brachytherapy using a magnetic resonance imaging-compatible applicator followed by both computed tomography and magnetic resonance imaging. The tumour and organs at risk (bladder, rectum, sigmoid and intestines) were contoured on computed tomography using only clinical findings and on magnetic resonance imaging using GEC-ESTRO guidelines. The volume and doses for tumour and organs at risk were evaluated using two-sided t-test. Results: When magnetic resonance imaging information is not included in contouring on computed tomography images, there is significant underestimation of tumour height and overestimation of the width (P , 0.05). However, there was no significant difference in V 100 , D 90 and D 100 for high-and intermediate-risk clinical target volume in computed tomography and magnetic resonance imaging. The volumes and doses to 0.1, 1 and 2 cc for organs at risk were also similar. Conclusions: Magnetic resonance imaging remains the gold standard for tumour delineation, but computed tomography with clinical information can give comparable results, which need to be studied further. Computed tomography-based contouring can be used comfortably for delineation of organs at risk.
Journal of Contemporary Brachytherapy, 2022
Purpose: The purpose of the study was to consider and calculate dosimetric parameters during treatment planning to improve radiobiological outcomes for cervical cancer patients treated with high-dose-rate (HDR) intracavitary brachytherapy (ICBT). Material and methods: In the present study, dose volume histograms (DVH) of 30 cervical cancer patients treated with HDR brachytherapy using computer tomography (CT)-based planning were analyzed. High-risk clinical target volume (HR-CTV) was contoured as the main target volume for all the patients, with an assumption that there was no presence of gross tumor at the time of brachytherapy. Values of target coverage volumes (100%, 150%, and 200%) were obtained from DVH, which was used to calculate different quality indices (QIs), including coverage index (CI), dose homogeneity index (DHI), overdose volume index (ODI), and dose non-uniformity ratio (DNR). Values of these QIs were further used to calculate tumor control probability (TCP). Statistical correlation between all QIs with TCP was established. Also, normal tissue complication probabilities for bladder (NTCP_B) and rectum (NTCP_R) were calculated. Results: The mean values of the various calculated parameters, including CI,
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...
Journal of Radiation Research, 2012
This study was performed to evaluate the feasibility of magnetic resonance imaging (MRI) in the treatment planning of image-guided brachytherapy for cervical carcinoma. Seventeen consecutive patients with locally advanced cervical cancer were enrolled in the study. Fifteen patients could be evaluated. When comparing the tumor at diagnosis (GTV-Dx) and the tumor at the first brachytherapy (GTV-BT), 11 of 15 patients showed a tumor regression of more than 80% while only four patients had less than 80% tumor regression. The mean D90 of HR-CTV and the calculated D2cc of the bladder, rectum, and sigmoid were 99.2 ± 11 Gy, 87.7 ± 5.7 Gy, 68.4 ± 5.4 Gy and 70.3 ± 6.8 Gy, respectively. No grade 3-4 acute toxicity was observed. The MRI can be a valuable tool for evaluating tumor response after external beam radiotherapy (EBRT) and is very helpful for prognosis prediction by residual GTV evaluation. Furthermore, MRI-guided brachytherapy allowed us to optimize the dose for both the target volumes and the OARs.