Vaginal Dose Point Research Articles

Vaginal Dose Reduction by Changing the Ovoid Loading Pattern in Image Guided Intracavitary Brachytherapy of Cervix.

Locally advanced cervical cancer is frequently treated using a combination of external beam radiotherapy and brachytherapy. Radiotherapy often leads to vaginal morbidity, which poses a significant problem. This study aims to analyze the impact of reducing ovoid loading on dosimetry. We analyzed forty-five CT-based intracavitary brachytherapy plans from fifteen patients. Three plan sets were created for the 45 applications: a standard loading plan (A), a plan with reduced ovoid loading (B), and a tandem-only loading plan (C). We generated Dose-Volume Histograms and recorded dose volume parameters for the three plan sets. The D90 for the Clinical Target Volume (CTV) did not show significant differences among the three plan sets (p = 0.20). The average D90 values for plans A, B, and C were 8.15Gy, 8.16Gy, and 7.4Gy, respectively. No statistically significant differences were observed in D2cc bladder (p = 0.09) (average values: 6.8Gy, 6.5Gy, and 5.9Gy for plans A, B, and C, respectively) and D2cc sigmoid (p = 0.43) (average values: 2.8Gy, 2.6Gy, and 2.4Gy, respectively) among the three plan sets. However, there was a statistically significant difference in D2cc rectum (p < 0.001) (average values: 4Gy, 3.3Gy, and 1.8Gy, respectively), as well as in vaginal dose points (p < 0.001). Reducing ovoid loading significantly decreased the doses to vaginal dose points and the rectum without compromising the dose to the Clinical Target Volume (CTV). Therefore, in carefully selected cases, the adoption of tandem-only loading or reduced ovoid loading could be considered to minimize vaginal morbidity following high dose rate intracavitary brachytherapy.

Feasibility of vaginal dose points reporting in cancer cervix patients treated by external beam radiotherapy and brachytherapy

Background: Cervical cancer is the second most common malignancy among women in India. The standard of treatment for locally advanced lesions is Concurrent Chemoradiation with External Beam Radiotherapy followed by Intracavitary Brachytherapy (GEC-ESTRO). The dose received by the entire vagina cannot be accurately measured by a vaginal dose point assessment at the level of the ovoids alone. Aims and Objectives: Our study aims to see the feasibility of measuring vaginal dose at various levels and define the dose points that can be practiced in 2D and 3D external radiation and brachytherapy (BT). Materials and Methods: Radiotherapy plans of 29 patients with stages IIA to IVA cancer cervix treated with concurrent chemoradiation from January 2020 to December 2020 were retrospectively reviewed for the feasibility of measuring the vaginal dose points throughout the vagina. Every patient underwent cisplatin-based weekly chemotherapy along with BT and external beam radiotherapy. We have assessed the vaginal dose locations 2 cm above and below the point of the posteroinferior border of the pubic symphysis (PIBS). The superior surface of the ovoid to the PIBS point constitutes the vaginal reference length (VRL). Results: The mean and median doses from external beam radiation therapy (EBRT) were 50Gy and 51 Gy at PIBS, 52 Gy and 53.5 Gy at +2 cm, and 18Gy and 28 Gy at -2 cm, respectively. The combined mean and median EQD2 doses from EBRT and BT at PIBS, PIBS+2, and at PIBS-2 were 56 and 57 Gy, 65 and 66 Gy, and 35 and 31 Gy, respectively. The mean VRL was 5.25 cm before EBRT and 4.75 cm before BT. Conclusion: Our study found that it is feasible to measure the dose received by the vagina using the PIBS system and large dose variations throughout the vagina were observed.

The Choice of 2D-Brachytherapy or 3D-Brachytherapy for Cervical Cancer Patients after External Beam Radiation Based on Residual Gross Tumor Volume

<h3>Purpose/Objective(s)</h3> The purpose of this study was to analyze the choice of 2-dimensional brachytherapy (2D-BT) or 3-dimensional brachytherapy (3D-BT) for cervical cancer patients after external beam radiotherapy (EBRT), based on residual gross tumor volume (GTV res). <h3>Materials/Methods</h3> Between September 2019 and April 2020, 106 local advanced cervical cancer patients (FIGO stage IB3-IVA) who received primary radiation or chemoradiation followed by BT were analyzed retrospectively. We divided patients into large tumor group (GTV res > 30 mm³ or the width ≥ 4 cm) and small tumor group (GTV res ≤ 30 mm³). Point A and high-risk clinical target volume (CTV_HR) planning were designed for each patient; all patients received 4–5 fractions of intra-cavity BT with a single dose of 6 Gy. The CTV_HR, the bladder, and rectum were delineated, respectively, the D2cc (minimum dosage to the most irradiated 2 cc of an organ at risk) of bladder and rectum, D90 (dose to 90% of a target) of the target, vaginal dose point, and vaginal reference length (VRL) were compared. <h3>Results</h3> The patients who received BT fewer than 4 times (n = 2), had double primary tumors (n = 1), or had incomplete data (n = 3) were excluded. Thus, 106 patients were eligible and analyzed in this study. Of the 106 patients, 45 (42.5%) had an initial tumor size of > 4 cm before EBRT. After EBRT, 92 (86.8%) patients had small GTV res, the median of GTV res and CTV_HR were 2 cm³ and 17.85 cm³. The CTV_HR does not change with GTV res (r² = 0.16, <i>P</i> < 0.001), no matter the size of GTV res, both the point A dose and CTV_HR can satisfactorily reach the prescribed tumor coverage dose. However, when evaluated by volume dose, the CTV-_HR D90 was higher than the Point A dose; with reduced organs at risk (OARs) dose (bladder, rectum-, and vaginal dose point) (<i>P</i> < 0.05). The remainder of the patients had large GTV res, with a median of 64cm³, which is not covered by the Point A dose. While evaluated by volume dose, the median of CTV_HR was 71.6 cm³; as GTV res increased, the CTV_HR increased significantly (r² = 0.68, <i>P</i> < 0.001). The CTV_HR D90 to Point A dose ratio was negatively correlated with GTV res (r = -0.61, <i>P</i> < 0.001), and the Point A dose typically varied between 47% and 230% of the CTV_HR D90. In the OARs dose evaluation, only the vaginal dose points were lower in the CTV_HR plan. The 1-year and 2-year local controls for small and large tumor groups were 94.3% versus 78.6% and 91.9% versus 70.7%, respectively. <h3>Conclusion</h3> After EBRT, 86.8% of locally advanced cervical cancer (LACC) patients had small residual tumors, and 2D-BT can achieve adequate prescription dose coverage and meet treatment needs. Only 13.2% of patients had large residual tumors, and these patients should receive 3D-BT or treatment combined with interstitial needles to deliver a higher dose to the CTV_HR. To protect the OARs and reduce radiation damage in small resident tumor patients, 3D-BT would be the best choice.

The association of vagina equivalent dose in 2Gy fraction (EQD2) to late vagina toxicity in patients of cervical cancer treated with WPRT plus IGABT

To evaluate the associations of vaginal dose parameters and incidence of vaginal stenosis in patients with cervical cancer treated with image-guided brachytherapy (IGBT). Fifty-four patients with cervical cancer treated with IGBT were included. The vagina contouring was done on previously treated CT images and the vaginal dose points were marked. The cumulative dose in EQD2 from EBRT and IGBT was calculated for both aspects and the vaginal toxicity was evaluated. At median follow-up time of 18.5 months, grade 2 or higher vaginal stenosis was observed in 24% of patients. On univariate analysis, parameters that were associated with ≥ grade 2 vaginal stenosis were age, mean dose of lateral 5 mm vagina, dose at PIBS-2 cm, mid vaginal D0 .03cc, mid vagina D1cc, lower vagina D0.03cc, lower vagina D0.1cc, lower vagina D1cc and lower vagina D2cc. On multivariate analysis, the significant parameters were age > 68.5 years old (P = 0.038), mean dose of lateral 5-mm (P = 0.034), and dose at PIBS-2 cm (P = 0.042). Age > 68.5 years old, mean dose of lateral 5 mm vagina and dose at PIBS-2 cm were associated with grade 2 or higher vaginal stenosis.

Dose-effect relationship between vaginal dose points and vaginal stenosis in cervical cancer: An EMBRACE-I sub-study

Background and purposeTo evaluate dose–effect relationships between vaginal dose points and vaginal stenosis in patients treated for locally advanced cervical cancer with radio(chemo)therapy and image-guided adaptive brachytherapy. Material and methodsPatients from six centres participating in the EMBRACE-I study were included. Information on doses to different vaginal dose points, including the Posterior-Inferior Border of Symphysis (PIBS) points and recto-vaginal reference (RV-RP) point, were retrieved from the treatment planning system. In addition, the vaginal reference length (VRL) was evaluated. Vaginal stenosis was prospectively assessed according to the CTCAEv3.0 system at baseline and follow-up. Primary endpoint was grade 2 or higher (G ≥ 2) vaginal stenosis. Impact of dose to the vaginal dose points, and impact of VRL, age, vaginal involvement and applicator on vaginal stenosis G ≥ 2 was evaluated with a Cox proportional-hazard regression model. Results301 patients were included. Median follow-up was 49 months. During follow-up, the incidence of G0, G1, G2, and G3 vaginal stenosis was 25% (76), 52% (158), 20% (59) and 3% (8), respectively. Median total doses to PIBS+2 cm, PIBS, PIBS-2 cm and the RV-RP were 52.9 (IQR 49.3–64.7), 41.0 (IQR 15.4–49.0), 4.1 (IQR 2.9–7.0) and 64.6 (IQR 60.0–70.6) Gy EQD23, respectively. Higher doses to the PIBS, PIBS + 2 cm and RV-RP points were significantly associated with increased risk for vaginal stenosis G ≥ 2. Other risk factors for vaginal stenosis were: vaginal involvement at diagnosis, higher age, shorter VRL and use of a tandem-ovoid applicator. ConclusionHigher doses to the PIBS+2 cm, PIBS and RV-RP dose points are associated with vaginal stenosis G ≥ 2.

PO-0225 Automatic reporting of vaginal dose points for cervical cancer HDR-brachytherapy

PO-0225 Automatic reporting of vaginal dose points for cervical cancer HDR-brachytherapy

OC-1049: Dose-effect relationship between vaginal dose points and vaginal stenosis in cervical cancer

OC-1049: Dose-effect relationship between vaginal dose points and vaginal stenosis in cervical cancer

Inter-observer and intra-observer variability in reporting vaginal dose points for cervical cancer in high-dose-rate brachytherapy.

PurposeThe ICRU 89 recommends reporting a set of vaginal dose points for cervical cancer treatments in order to quantify the goodness of implant. This vaginal dose reporting method for combined external beam radiotherapy and brachytherapy has been adopted by the EMBRACE II study protocol. Large variations in dose between patients and centers have been reported. The aim of this study was to determine possible discrepancies with consensus observers from the same institution. Therefore, the inter- and intra-observer variability were analyzed.Material and methodsFor five patients, five experienced observers reported dose at the proposed vaginal points twice. The effect of inter- and intra-observer variations on total dose was analyzed by estimating biologically equivalent dose EQD2 (α/β = 3 Gy). Coefficient of variation (CV) was used to provide a measure of data dispersion as a proportion to the mean.ResultsThe maximum inter-observer deviation among all patients and all points ranged from 0.5 Gy to 24.1 Gy in EQD2. The higher inter-observer discrepancies were found at points at 3 o’clock and at 6 o’clock, with respect to ovoids. In case of the maximum intra-observer deviation, it ranged from 0.5 Gy to 14.2 Gy, with higher deviation points at 12 o’clock and 9 o’clock, with respect to ovoids.ConclusionsThere is a need to ensure consistency in vaginal points reporting. The impact of the dosimetric inter- and intra-observer variability should also be considered when dealing with dose tolerances and limits due to the potential dose gradient.

PO-1017: Interobserver variability of vaginal dose points reporting in cervical cancer radiotherapy treatment

PO-1017: Interobserver variability of vaginal dose points reporting in cervical cancer radiotherapy treatment

Vaginal dose de-escalation in image guided adaptive brachytherapy for locally advanced cervical cancer

PurposeVaginal stenosis is a major problem following radiotherapy in cervical cancer. We investigated a new dose planning strategy for vaginal dose de-escalation (VDD). Materials and methodsFifty consecutive locally advanced cervical cancer patients without lower or middle vaginal involvement at diagnosis from 3 institutions were analysed. External beam radiotherapy was combined with MRI-guided brachytherapy. VDD was obtained by decreasing dwell times in ovoid/ring and increasing dwell times in tandem/needles. The aim was to maintain the target dose (D90 of HR-CTV⩾85Gy EQD2) while reducing the dose to the surface of the vagina to <140% of the physical fractional brachytherapy dose corresponding to a total EQD2 of 85Gy. ResultsThe mean vaginal loading (ovoid/ring) was reduced from 51% to 33% of the total loading with VDD, which significantly reduced the dose to the vaginal dose points (p<0.001) without compromising the target dose. The dose to the ICRU recto-vaginal point was reduced by a mean of 4±4Gy EQD2 (p<0.001), while doses to bladder and rectum (D2cm3) were reduced by 2±2Gy and 3±2Gy, respectively (p<0.001). ConclusionsVDD significantly reduces dose to the upper vagina which is expected to result in reduction of vaginal stenosis.

Multicentre evaluation of a novel vaginal dose reporting method in 153 cervical cancer patients

Background and purposeRecently, a vaginal dose reporting method for combined EBRT and BT in cervical cancer patients was proposed. The current study was to evaluate vaginal doses with this method in a multicentre setting, wherein different applicators, dose rates and protocols were used. Material and methodsIn a subset of patients from the EMBRACE study, vaginal doses were evaluated. Doses at the applicator surface left/right and anterior/posterior and at 5mm depth were measured. In addition, the dose at the Posterior–Inferior Border of Symphysis (PIBS) vaginal dose point and PIBS±2cm, corresponding to the mid and lower vagina, was measured. Results153 patients from seven institutions were included. Large dose variations expressed in EQD2 with α/β=3Gy were seen between patients, in particular at the top left and right vaginal wall (median 195 (range 61–947)Gy/178 (61–980)Gy, respectively). At 5mm depth, doses were 98 (55–212)Gy/91 (54–227)Gy left/right, and 71 (51–145)Gy/67 (49–189)Gy anterior/posterior, respectively. The dose at PIBS and PIBS±2cm was 41 (3–81)Gy, 54 (32–109)Gy and 5 (1–51)Gy, respectively. At PIBS+2cm (mid vagina) dose variation was coming from BT. The variation at PIBS−2cm (lower vagina) was mainly dependent on EBRT field border location. ConclusionsThis novel method for reporting vaginal doses coming from EBRT and BT through well-defined dose points gives a robust representation of the dose along the vaginal axis. In addition, it allows comparison of vaginal dose between patients from different centres. The doses at the PIBS points represent the doses at the mid and lower parts of the vagina. Large variations in dose throughout the vagina were observed between patients and centres.

Reporting Vaginal Dose Point in Cervical Cancer Patients of Asian Origin Treated With Combine 3D External Beam Radiotherapy and 3D Brachytherapy and Comparing It With a Caucasian Population - Is There a Difference?

Purpose: To investigate the clinical feasibility and treatment outcomes of image-based high dose rate (HDR) brachytherapy using an intracavitary multichannel vaginal cylinder for the definitive treatment of vaginal cancers Materials and Methods: Forty-one patients with vaginal cancer (24% primary vaginal, 76% recurrence from other gynecologic primaries) treated with definitive radiotherapy chemotherapy including imagebased HDR brachytherapy with a multichannel vaginal cylinder. Imagebased brachytherapy was completed using either CT-based (41%) or MR-based planning (59%) with each fraction. The high-risk clinical target volume (HR-CTV) was defined based on the preand post-external beam radiotherapy GTV (see Figure). Doses were converted to equivalent dose of 2Gy per fraction (EQD2Gy). Endpoints examined: dose-volume parameters and early clinical outcomes. Results: The median HR-CTV volume was 24.2cc [Interquartile range (IQR): 12.6], with a median dose to 90% (D90) of 77.1Gy (IQR: 3.4). The median dose to 2cc (D2cc) for the bladder, rectum, and sigmoid were 59.4Gy (IQR: 5.6), 58.2Gy (IQR: 4.1), and 52.3Gy (IQR: 5.5) respectively. After a median follow-up of 16 months (range: 3-35), complete clinical response was documented in 98% of patients. The 2year local control, regional control, distant control, disease free survival and overall survival were 93%, 100%, 81%, 78% and 88%. The 2-year actuarial rate of late $ grade 3 toxicity was 4% overall with 0% vaginal, 0% bladder, urethral 0%, and 4% gastrointestinal, respectively. Conclusions: Image-based HDR brachytherapy using an intracavitary multichannel cylinder appears feasible in definitive vaginal cancer treatment. The described clinical implementation of image-based multichannel cylinder brachytherapy, including concepts of HR-CTV delineation, patient selection, and dose-constraints show promising early clinical outcomes with high rates of local control and little toxicity which should be validated with extended follow-up.

The Associations for Vaginal Point Doses of Vaginal Stenosis in Image-Guided Brachytherapy

Purpose: To evaluate the associations for vaginal dose points of vaginal stricture in image-guided brachytherapy. Materials and Methods: Twenty-six patients of locally advanced cervical cancer were treated with Image-Guided Brachytherapy (IGBT) with the dose at least 7 Gy per fraction to the D90 of High-Risk Clinical Target Volume (HR-CTV). The vaginal dose points of recommendations of the American Brachytherapy Society (ABS) were added into the plan and cumulative dose to these points was evaluated in Equivalent Dose of 2 Gy (EQD2) concepts. Results: The mean doses to right vaginal dose point (VR), left vaginal dose point (VL) and average dose of VR/VL ((VR + VL)/2) were 101.5 Gy, 98.2 Gy and 99.8 Gy in EQD2 concepts, respectively. Volume-based planning significantly reduced the cumulative dose in EQD2 concepts at vaginal points. At the median follow-up time of 22 months, grade-2 vaginal stricture was observed in two patients. The incidences of vaginal stricture were not differed between the cumulative dose to vaginal dose points in EQD2 concepts of ≤90 Gy versus >90 Gy (P = 1.000) and ≤100 Gy versus >100 Gy (P = 0.815). Conclusion: No association for cumulative vaginal doses and events of vaginal stricture was found.

Vaginal dose point reporting in cervical cancer patients treated with combined 2D/3D external beam radiotherapy and 2D/3D brachytherapy

Background and purposeTraditionally, vaginal dose points have been defined at the vaginal source level, thus not providing dose information for the entire vagina. Since reliable vaginal dose volume/surface histograms are unavailable, a strategy for comprehensive vaginal dose reporting for combined EBRT and BT was established and investigated. Material and methodsAn anatomical vaginal reference point was defined at the level of the Posterior–Inferior Border of Symphysis (PIBS), plus two points ±2cm (mid/introitus vagina). For BT extra points were selected for the upper vagina at 12/3/6/9o’clock, at the vaginal surface and 5mm depth. A vaginal reference length (VRL) was defined from ring centre to PIBS. Fifty-nine patients treated for cervical cancer were included in this retrospective feasibility study. ResultsThe method was applicable to all patients. Total EQD2 doses at PIBS and ±2cm were 36.7Gy (3.1–68.2), 49.6Gy (32.1–89.6) and 4.3Gy (1.0–46.6). At the vaginal surface at ring level doses were respectively 266.1Gy (67.6–814.5)/225.9Gy (61.5–610.5) at 3/9o’clock, and 85.1Gy (55.4–140.3)/72.0Gy (49.1–108.9) at 12/6o’clock. Mean VRL on MRI was 5.6cm (2.0–9.4). ConclusionsWith this novel system, a comprehensive reporting of vaginal doses is feasible. The present study has demonstrated large dose variations between patients observed in all parts of the vagina, resulting from different contributions from EBRT and BT.

OC-0361: Vaginal dose point reporting in cervical cancer patients treated with combined EBRT and MRI-guided BT

OC-0361: Vaginal dose point reporting in cervical cancer patients treated with combined EBRT and MRI-guided BT

ANÁLISIS DOSIMÉTRICO EN BRAQUITERAPIA GINECOLÓGICA DE ALTA TASA DE DOSIS

SUMMARY Objective: We analyze the gynecologycal high dose rate brachytherapy dosimetry using the FletcherSuit-Delclos device, comparing orthogonal films (anteroposterior and lateral) versus axial computarized tomography. Methods: 4 implants were analized with orthogonal films and axial computarized tomography in the Brachyhterapy Unit of the National Cancer Institute on February 2006. The dose/fraction was 8 Gy to the H point. The bladder, rectal and vaginal dose point were evaluated according to international specifications. Results: Axial computarized tomography reveals hot points higher than orthogonal films dosimetries (133% and 260% for bladder and rectum respectively). The target volumen included was underestimated with the classical orthogonal film dosimetry. Conclusions: The orthogonal film dosimetry shows smaller accuracy than axial computarized tomography. The target volumens were not satisfactorily covered by the prescribed isodosis curve. The dose accumulated could, probably, be more prominent than the dose/fraction.