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MRI sequences with short scanning times may improve accessibility of image guided adaptive brachytherapy (IGABT) of cervix cancer. We assessed the value of 3D MRI for contouring by comparing it to 2D multi-planar MRI.
In 14 patients, 2D and 3D pelvic MRI were obtained at IGABT. High risk clinical target volume (HR CTV) was delineated by 2 experienc...
Contexts in source publication
Context 1
... the inter-approach Bland-Altman analy- sis, high agreement in HR CTV sizes was found for both observers (Table 1). A favourable mean VCI of 0.8 (SD 0.03) and 0.79 (SD 0.04) was obtained for observer 1 and 2, respectively. ...
Context 2
... the inter-observer analysis, high agreement in HR CTV sizes was found for both approaches (Table 1). Favourable mean VCI on conventional approach of 0.76 (SD 0.05) was maintained on test approach (mean VCI: 0.75; SD 0.05). ...
Context 3
... the agreement increases, VCI approaches 1. Small dif- ferences in HR CTV sizes (Table 1) and favourable results on VCI, obtained in our study, indicate high level of volumetric agreement between the conven- tional and test delineations. An inter-approach VCI of around 0.8 compares favourably with results of similar studies both in the field of EBRT and BT. ...
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Material and methods
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Purpose
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Citations
... For example, with multiplanar acquisitions, the reformatting may also result in the loss of image quality. 105 With 3D imaging, one has the ability to reconstruct images in any plane. Although considered optional by GEC-ESTRO, 3D T2W imaging is also recommended with the understanding that this will generally lead to increased scanning time, which increases artifacts due to motion. ...
... It has been suggested that quantitative imaging may further improve the accuracy of target and subvolume target delineation. 105 With DWI one can identify areas of restricted water diffusion as areas of high cellularity, for example, tumors versus normal tissues. The utility of DWI and the derived apparent diffusion coefficient (ADC) map has been used for tumor visualization and therapy response in cervical cancer. ...
... The ICRU report 89 emphasizes state-of-the-art methods for delineating target volumes, OAR, dose, and volume parameters for prescribing, recording, and reporting cervical cancer brachytherapy [19]. Training radiation oncologists on a selected delineation protocol with analyses of results led to improved concordance and reduced contouring uncertainties among inter-and intra-observers in IGABT [58][59][60][61]. ...
The use of brachytherapy (interventional radiotherapy) in the treatment of gynecological
cancers is a crucial element in both definitive and adjuvant settings. The recent developments in
high‐dose rate remote afterloaders, modern applicators, treatment‐planning software, image guidance,
and dose monitoring systems have led to improvement in the local control rates and in some
cases improved the survival rates. The development of these highly advanced and complicated
treatment modalities has been accompanied by challenges, which have made the existence of quality
assurance protocols a must to ensure the integrity of the treatment process. Quality assurance
aims at standardizing the technical and clinical procedures involved in the treatment of patients,
which could eventually decrease the source of uncertainties whether technical (source/equipment
related) or clinical. This commentary review sheds light (from a clinical point of view) on some
potential sources of uncertainties associated with the use of modern brachytherapy in the treatment
of gynecological cancers.
... Three-Dimensional T2-weighted fast spin echo sequences with isotropic voxels are capable of producing images suitable for contouring 25 with excellent visualization of the applicator in all spatial directions, improving applicator tip detection and reducing overall MR imaging time. 26,27 Note that the tissue appearance in 3D T2-weighted and multiplanar 2D scans are not identical ( Fig. 1) and therefore institutions should be cautious if deciding to forego the goldstandard 2D T2-weighted sequence. The choice of MR sequences is important for the accuracy of applicator reconstruction. ...
The incorporation of magnetic resonance imaging in brachytherapy has resulted in an
increased use of interstitial catheters in order to create a comprehensive treatment plan
that covers the visualized tumor. However, the insertion with passive, image-guidance
requires estimating the location of the tumor during the insertion process, rather than visualizing and inserting the catheters directly to the desired location under active tracking. In order to treat residual disease, multiparametric MR sequences can enhance the information available to the clinician. The precision availed by MR-guided brachytherapy results in substantial improvements in needle positioning, and resulting treatment plans.
... The slice width employed in axial images (usually 3-4 mm) may lead to certain inaccuracy, which can be reduced by using additional image sequences, such as para-sagittal 44 or 3D. 45 Titanium applicators and needles produce a void signal on the MRI, the determination of the source path inside them being therefore difficult. Furthermore, they induce susceptibility artifacts, ballooning, at the end of the applicator and needles. ...
Brachytherapy plays an essential role in the curative intent management of locally advanced cervical cancer. The introduction of the magnetic resonance (MR) as a preferred image modality and the development of new type of applicators with interstitial components have further improved its benefits. The aim of this work is to review the current status of one important aspect in the cervix cancer brachytherapy procedure, namely catheter reconstruction. MR compatible intracavitary and interstitial applicators are described. Considerations about the use of MR imaging (MRI) regarding appropriate strategies for applicator reconstruction, technical requirements, MR sequences, patient preparation and applicator commissioning are included. It is recommendable to perform the reconstruction process in the same image study employed by the physician for contouring, that is, T2 weighted (T2W) sequences. Nevertheless, a clear identification of the source path inside the catheters and the applicators is a challenge when using exclusively T2W sequences. For the intracavitary component of the implant, sometimes the catheters may be filled with some substance that produces a high intensity signal on MRI. However, this strategy is not feasible for plastic tubes or titanium needles, which, moreover, induce magnetic susceptibility artifacts. In these situations, the use of applicator libraries available in the treatment planning system (TPS) is useful, since they not only include accurate geometrical models of the intracavitary applicators, but also recent developments have made possible the implementation of the interstitial component. Another strategy to improve the reconstruction process is based on the incorporation of MR markers, such as small pellets, to be used as anchor points. Many institutions employ computed tomography (CT) as a supporting image modality. The registration of CT and MR image sets should be carefully performed, and its uncertainty previously assessed. Besides, an important research work is being carried out regarding the use of ultrasound and electromagnetic tracking technologies.
... This method has been used before and is described in detail. 27,28,30 Briefly, the inter-delineation distances (IDD) were calculated between each voxel of observer's contour and nearest voxel of the EC contour in 72 angular steps of 5 degrees for all slices. 27,28,30 ...
... 27,28,30 Briefly, the inter-delineation distances (IDD) were calculated between each voxel of observer's contour and nearest voxel of the EC contour in 72 angular steps of 5 degrees for all slices. 27,28,30 ...
Background
Omitting the placement of clips inside tumour bed during breast cancer surgery poses a challenge for delineation of lumpectomy cavity clinical target volume (CTV
Patients and methods
CT- and MRI-simulator images of 12 breast cancer patients, treated by breast conserving surgery and radiotherapy, were included in this study. Five radiation oncologists recorded the cavity visualization score (CVS) and delineated CTV
Results
Mean CVS was 3.88 +/− 0.99 and 3.05 +/− 1.07 for MRI and CT, respectively (p = 0.001). Mean volumes of CTV
Conclusions
When compared with CT, MRI improved visualization of post-lumpectomy changes, reduced interobserver variation and improved the accuracy of CTV
... Mean inter-delineation distance was 4.2 mm, 3.8 mm and 5.2 mm for GTV, HR CTV and IR CTV, respectively. 25,35 ...
Background
Modern radiotherapy techniques enable delivery of high doses to the target volume without escalating dose to organs at risk, offering the possibility of better local control while preserving good quality of life. Uncertainties in target volume delineation have been demonstrated for most tumour sites, and various studies indicate that inconsistencies in target volume delineation may be larger than errors in all other steps of the treatment planning and delivery process. The aim of this paper is to summarize the degree of delineation uncertainties for different tumour sites reported in the literature and review the effect of strategies to minimize them.
Conclusions
Our review confirmed that interobserver variability in target volume contouring represents the largest uncertainty in the process for most tumour sites, potentially resulting in a systematic error in dose delivery, which could influence local control in individual patients. For most tumour sites the optimal combination of imaging modalities for target delineation still needs to be determined. Strict use of delineation guidelines and protocols is advisable both in every day clinical practice and in clinical studies to diminish interobserver variability. Continuing medical education of radiation oncologists cannot be overemphasized, intensive formal training on interpretation of sectional imaging should be included in the program for radiation oncology residents.
... (mostly between 0.70-0.79) for high-risk clinical target volume (HRCTV) [7][8][9][10][11]. ...
... Our CI for GTV B (0.57) is consistent with that reported previously in the T2w literature (0.58-0.60) [7][8][9][10][11]. The largest published contouring study was multi-institutional and developed in the setting of the EMBRACE (an intErnational study on MRIguided BRachytherapy in locally advanced CErvical cancer, www. ...
Background and purpose:
We examined the utility of dynamic contrast-enhanced MRI (DCE-MRI), diffusion-weighted MRI (DWI), and FDG-PET imaging for brachytherapy target delineation in patients with locally advanced cervical cancer.
Materials and methods:
Twenty-two patients had DWI, DCE-MRI, and FDG-PET/CT scans after brachytherapy applicator insertion, in addition to standard T2-weighted (T2w) 3T MRI. Gross tumor volume (GTVB) and high-risk clinical target volume (HRCTV) were contoured first on T2w images, and then modified if indicated upon review of DWI/DCE-MRI/FDG-PET images by two observers. The primary endpoint was utility, determined by the number of patients whose volumes were modified, and interobserver variability.
Results:
Eleven patients' T2w-GTVB were modified based on DWI/DCE-MRI/FDG-PET by observer 1, due to clearer demarcation (7) and residual disease not well visualized on T2w MRI (4). GTVB was modified in 17 patients by observer 2 (11 and 6, respectively). Incorporation of functional imaging improved the conformity index (CI) for GTVB from 0.54 (T2w alone) to 0.65 (P=0.003). HRCTV was modified in 3 and 8 patients by observers 1 and 2, respectively, with a trend toward higher CI using functional imaging (0.71 to 0.76, P=0.06).
Conclusions:
DWI/DCE-MRI/FDG-PET imaging as a supplement to T2w MRI decreased interobserver variability in GTVB delineation.
... 43 The observers in published inter-observer studies on cervical cancer IGABT were experts, participating in the EMBRACE protocol (IntErnational study on MRI-guided BRAchytherapy in locally advanced CErvical cancer) or contouring instructors. [44][45][46][47][48] GEC ESTRO recommendations were strictly applied in these studies. 38,50 In spite of the favourable circumstances, the magnitude of "residual" uncertainties at expert level was substantial and was reflected in clinically relevant uncertainties of the reported DVH parameters. ...
Standard applicators for cervical cancer Brachytherapy (BT) do not always achieve acceptable balance between target volume and normal tissue irradiation. We aimed to develop an innovative method of Target-volume Density Mapping (TDM) for modelling of novel applicator prototypes with optimal coverage characteristics. Patients and methods. Development of Contour-Analysis Tool 2 (CAT-2) software for TDM generation was the core priority of our task group. Main requests regarding software functionalities were formulated and guided the coding process. Software validation and accuracy check was performed using phantom objects. Concepts and terms for standardized workflow of TDM post-processing and applicator development were introduced.
... By omitting multi-planar MRI and employing 3D MRI for pre-planning, total image acquisition time was shortened for approximately 50%, when compared to our standard MRI study at time of actual BT. 43 In fact, due to the possibility to achieve an optimal implant already at the first application, the described procedure may serve as a basis for accomplishment of BT in a reduced number of optimized insertions, reducing the total MRI-time and costs. The clinical impact of favourable dosimetric results of IGABT in our patient population remains to be quantified and compared with our retrospective series on conventional 2D BT. 44 ...
Background
Optimal applicator insertion is a precondition for the success of cervix cancer brachytherapy (BT). We aimed to assess feasibility and efficacy of MRI-assisted pre-planning, based on applicator insertion in para-cervical anaesthesia (PCA).
Patients and methods.
Five days prior to BT, the pre-planning procedure was performed in 18 cervix cancer patients: tandem-ring applicator was inserted under PCA, pelvic MRI obtained and applicator removed. Procedure tolerability was assessed. High risk clinical target volume (HR CTV) and organs at risk were delineated on the pre-planning MRI, virtual needles placed at optimal positions, and dose planning performed. At BT, insertion was carried out in subarachnoidal anaesthesia according to pre-planned geometry. Pre-planned and actual treatment parameters were compared.
Results
Pre-planning procedure was well tolerated. Median difference between the pre-planned and actual needle insertion depth and position were 2 (0–10) mm and 4 (0–30) degrees, respectively. The differences between the pre-planned and actual geometric and dosimetric parameters were statistically non-significant. All actual needles were positioned inside the HR CTV and outside the organs at risk (OAR).
Conclusions
Our pre-planning approach is well tolerated and effective. Pre-planned geometry and dose distribution can be reproduced at BT.
... [4][5][6][7][8] 3D MRI could potentially replace multiplanar 2D MRI in cervix cancer IGABT (image guided adaptive MRI based brachytherapy), shortening the overall MRI scanning time and facilitating the contouring process, thus making this treatment method more widely employed. 9 Intracavitary brachytherapy of cervical cancer consists of multiple applications, usually four to five. As recommended by the GEC-ESTRO work group, it is important for the 3D image guided adaptive MRI based brachytherapy of cervical cancer to verify what is the minimum dose received by the most irradiated 0.1 cm 3 , 1 cm 3 and 2 cm 3 (D 0.1cc , D 1cc and D 2cc , respectively) of the bladder and rectum volume. ...
Background
The aim of the study was to examine on the CT basis the inter-application displacement of the positions D0.1cc, D1cc and D2cc of the brachytherapy dose applied to the bladder and rectum of the patients with inoperable cervical cancer.
Patients and methods
This prospective study included 30 patients with cervical cancer who were treated by concomitant chemo-radiotherapy. HDR intracavitary brachytherapy was made by the applicators type Fletcher tandem and ovoids. For each brachytherapy application the position D0.1cc was determined of the bladder and rectum that receive a brachytherapty dose. Then, based on the X, Y, and Z axis displacement, inter-application mean X, Y, and Z axis displacements were calculated as well as their displacement vectors (R). It has been analyzed whether there is statistically significant difference in inter-application displacement of the position of the brachytherapy dose D0.1cc, D1cc and D2cc of the bladder and rectum. The ANOVA test and post-hoc analysis by Tukey method were used for testing statistical importance of differences among the groups analyzed. The difference among the groups analyzed was considered significant if p < 0.05.
Results
There are significant inter-application displacements of the position of the brachytherapy dose D0,1cc, D1cc and D2cc of the bladder and rectum.
Conclusions
When we calculate the cumulative brachytherapy dose by summing up D0,1cc, D1cc and D2cc of the organs at risk for all the applications, we must bear in mind their inter-application displacement, and the fact that it is less likely that the worst scenario would indeed happen.
