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Three-dimensional reconstruction of defined volumes using TPS Eclipse: supraclavicular lymph nodes (red); infraclavicular lymph nodes (sky blue); left breast (transparent light green); axilla (magenta); internal mammary chain (yellow); Rotter lymph node (blue); brachial plexus (green) between supra/infraclavicular nodes and axilla; sternum, clavicle and humeral bone (white); thyroid gland (pink); left lung (brown) and heart (dark blue).
Source publication
The purpose of the study was to evaluate the individual variability of anatomical and radiological delineation for breast cancer radiotherapy (RT) in preparation for new techniques and to propose practical solutions to improve delineation in everyday practice. In the first phase, a patient with stage T3N3M0 breast cancer and complete response after...
Contexts in source publication
Context 1
... variability and the differences in the delineated volumes were quantified and the standard deviation was calculated. Evaluation of the results of the first phase was presented at the Department of Radiation Oncology Meeting (Figure 2), an open discussion between all participants in this study supported by various examples from the literature. The training course was conducted in the anatomical setting. ...
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Aim:
To quantify the variability between radiation oncologists (ROs) when outlining axillary nodes in breast cancer.
Material and methods:
For each participating center, three ROs with different levels of expertise, i.e., junior (J), senior (S) and expert (E), contoured axillary nodal levels (L1, L2, L3 and L4) on the CT images of three differen...
Citations
... This personalised semiautomated approach to radiotherapy treatment planning could become the future clinical standard, because the algorithm will take individual patient anatomy and treatment position into account once the anatomical landmarks are properly indicated. On top of that, several publications state that interand intra-observer variability is high, even when delineations are made according to the same guidelines (as opposed to comparing delineations from different centres that might use slightly different guidelines) (Petersen et al., 2007;Castro Pena et al., 2009;Ciardo et al., 2017). Automating the process of delineation is also expected to reduce this inter-and intra-observer variability. ...
... 11 Even if the large number of available metrics makes the results from different studies difficult to be compared, their great value is to create awareness about the most common sources of sub-optimal contouring. [12][13][14] The axillary nodal contouring variability at multi-and intrainstitutional level was investigated in a previous study 15 endorsed by the Breast Study Group (BSG) of the Italian Association of Radiotherapy and Clinical Oncology (AIRO), where three radiation oncologists (ROs) with different expertise (the Expert, the Senior, the Junior) worked on three representative patients with different complexity (P1 "the simple anatomy", P2 "the obese", P3 "the altered arm set-up"). The group consensus was generated using the STAPLE algorithm and acted as reference mean contours for comparison calculations. ...
Objectives
To determine interobserver variability in axillary nodal contouring in breast cancer (BC) radiotherapy (RT) by comparing the clinical target volume of participating single centres (SC-CTV) with a gold-standard CTV (GS-CTV).
Methods
The GS-CTV of 3 patients (P1, P2, P3) with increasing complexity was created in DICOM format from the median contour of axillary CTVs drawn by BC experts, validated using the simultaneous truth and performance level estimation and peer-reviewed. GS-CTVs were compared with the correspondent SC-CTVs drawn by radiation oncologists, using validated metrics and a total score (TS) integrating all of them.
Results
Eighteen RT centres participated in the study. Comparative analyses revealed that, on average, the SC-CTVs were smaller than GS-CTV for P1 and P2 (by −29.25% and −27.83%, respectively) and larger for P3 (by +12.53%). The mean Jaccard index was greater for P1 and P2 compared to P3, but the overlap extent value was around 0.50 or less. Regarding nodal levels, L4 showed the highest concordance with the GS. In the intra patient comparison, L2 and L3 achieved lower TS than L4. Nodal levels showed discrepancy with GS which was not statistically significant for P1, and negligible for P2, while P3 had the worst agreement. DICE Similarity Coefficient did not exceed the minimum threshold for agreement of 0.70 in all the measurements.
Conclusions
Substantial differences were observed between SC- and GS-CTV, especially for P3 with altered arm set-up. L2 and L3 were the most critical levels. The study highlighted these key points to address.
Advances in knowledge
The present study compares, by means of validated geometric indexes, manual segmentationsof axillary lymph nodes in breast cancer from different observers and different institutionsmade on radiotherapy planning computed tomography images. Assessing such variability is ofparamount importance, as geometric uncertainties might lead to incorrect dosimetry andcompromise oncological outcome.
... Cette évolution a pu avoir lieu grâce à l'utilisation de l'imagerie scanographique pour la planification des irradiations des seins et ganglions. Les protocoles d'imagerie se sont affinés et les atlas ont permis une meilleure reproductibilité des délinéations des volumes cibles et organes à risque [26][27][28][29]. La Fig. 1 montre un exemple de délinéation pour la planification de traitement. ...
... Due to the possibility of changes in anatomical regions, different therapeutic techniques are considered for different disease stages, among which the techniques of common three-dimensional tangential fields and combinatory fields could be plausible options. In these techniques, electron fields, photons, or a combination of both fields are utilized [5][6][7][8][9]. ...
The aim of radiotherapy is to deliver the highest possible radiation dose to the tumor and the lowest radiation to normal tissues surrounding the tumor. In the present study, lymph nodes of the supraclavicular region were treated using two therapeutic techniques, namely photon technique (PT) and combinatory photon-electron technique (CPET). We recruited 50 patients with local lymph node metastasis. The photon energies were 6-15 MV. Furthermore, the electron beam energy was 18 MeV in CPET. The study findings revealed that the mean delivered dose to target volume was 41.12 ± 2.98Gy for PT and 44.56 ± 1.90Gy for CPET. The percentage of the target volume irradiated to 90% of the prescribed dose (V90) was calculated as 74.61% ± 9.30% and 82.06% ± 9.70% for PT and CPET, respectively. The mean dose delivered to the heart and lungs was not significantly different between the two groups. Furthermore, the maximum doses delivered to the spinal cord were 12.55Gy in PT and 8.89Gy in CPET. The mean doses delivered to the thyroid gland were 39.26 and 34.89Gy in PT and CPET. According to the study results, the maximum doses delivered to the spinal cord, head of the humerus bone, and thyroid were reduced significantly as measured the CPET technique. In contrast, no significant difference was observed regarding the dose delivered to the heart and lung. The dose delivered to the supraclavicular region determined by the CPET was significantly augmented. Furthermore, the coverage of the tumor mass was optimized using the new method.
... This personalised semiautomated approach to radiotherapy treatment planning could become the future clinical standard, because the algorithm will take individual patient anatomy and treatment position into account once the anatomical landmarks are properly indicated. On top of that, several publications state that interand intra-observer variability is high, even when delineations are made according to the same guidelines (as opposed to comparing delineations from different centres that might use slightly different guidelines) (Petersen et al., 2007;Castro Pena et al., 2009;Ciardo et al., 2017). Automating the process of delineation is also expected to reduce this inter-and intra-observer variability. ...
This review intends to rekindle efforts to map the lymphatic system by using a more modern approach, based on medical imaging. The structure, function, and pathologies associated with the lymphatic system are first discussed to highlight the need for more accurately mapping the lymphatic system. Next, the need for an interdisciplinary approach, with a central role for the anatomist, to come up with better maps of the lymphatic system is emphasized. The current approaches on lymphatic system research involving medical imaging will be discussed and suggestions will be made for an all‐encompassing effort to thoroughly map the entire lymphatic system. A first‐hand account of our integration as anatomists in the radiotherapy department is given as an example of interdisciplinary collaboration. From this account, it will become clear that the interdisciplinary collaboration of anatomists in the clinical disciplines involved in lymphatic system research/treatment still holds great promise in terms of improving clinical regimens that are currently being employed. As such, we hope that our fellow anatomists will join us in an interdisciplinary effort to map the lymphatic system, because this could, in a relatively short timeframe, provide improved treatment options for patients with cancer or lymphatic pathologies all over the world. Anat Rec, 302:1681–1695, 2019. © 2019 American Association for Anatomy
... Radiation oncologists aim to delineate the target volumes (breast, chest wall, nodal regions, tumor bed), and give a homogenous dose to these volumes and protect the organs at risk (OAR) in breast RT to limit the early and late side effects [12]. The heart should receive the lowest dose as possible in left breast RT [13]. ...
Purpose
We developed a heart atlas for breast radiation therapy and evaluated the influence of education on intra and inter-observer similarity, and cardiac dose reporting.
Materials and methods
The data of 16 left breast cancer patients were analyzed. Eight observers delineated heart and cardiac subunits [left (LCA) and right (RCA) coronary arteries, left anterior descending artery (LAD), bilateral atrium and ventricles] before the education. A radiologist and radiation oncologist developed the atlas and delineated the gold standard (GS) volumes. Observers repeated the delineation after education. RT plans were made for pre/post-atlas contours. The similarity was assessed by Dice (DSC) and Jaccard (JSC) similarity coefficient indices. The absolute difference rate was calculated for the dose analysis.
Results
The inter-observer similarity increased in heart and all subunits. The intra-observer similarity showed a heterogeneous distribution. The absolute difference rate in dose reporting was statistically significant for the bilateral atrium, right ventricle, LAD, LCA + LAD, RCA’s maximum doses (p < 0.05). The maximum dose reporting differences from the GS decreased from 16.9 to 8.9% for LAD (p = 0.011); from 14.8 to 9.3% for LCA + LAD (p = 0.010).
Conclusion
The cardiac atlas reduces the intra-interobserver differences and improves dose reporting consistency. The first intra-observer similarity analysis was made in our study and revealed the need for repeated education to increase the consistency.
... Target delineation is both the bedrock and the most vulnerable part of the process of treatment planning because it is prone to observer subjectivity based on personal opinion, knowledge and expertise [3]. Variations in the outlining of the target volume in breast cancer (BC) have been largely illustrated throughout the literature [4][5][6][7][8][9][10], with important implications for understanding tumor response and toxicity. Axillary node contouring showed poor interobserver agreement, particularly with regard to level III, even among experienced radiation oncologists (ROs) [11]. ...
... The kappa coefficient, the sensitivity rate, the specificity rate and the coefficient of variation (CV) are normally distributed, thus the central tendency and distribution correspond to mean and standard deviation, respectively, whereas the p values derive from the analysis of variance. The assumption of normal distribution is not valid for the center of mass distance (CMD), the dice similarity coefficient (DSC) and the 95% confidence interval of the Hausdorff distance (HD95), thus the central tendency and distribution correspond to median and interquartile range, respectively, whereas the and consensus guidelines have flourished over the years and have been shown to improve consistency in outlining, but major differences still exist among physicians [4][5][6][7][8][9][10]. Experts' consensus panel meetings achieved significant improvements in target delineation between pre-and post-consensus contours, in particular for heart, breast and chest wall [26]. ...
Aim:
To quantify the variability between radiation oncologists (ROs) when outlining axillary nodes in breast cancer.
Material and methods:
For each participating center, three ROs with different levels of expertise, i.e., junior (J), senior (S) and expert (E), contoured axillary nodal levels (L1, L2, L3 and L4) on the CT images of three different patients (P) of an increasing degree of anatomical complexity (from P1 to P2 to P3), according to contouring guidelines. Consensus contours were generated using the simultaneous truth and performance level estimation (STAPLE) method.
Results:
Fifteen centers and 42 ROs participated. Overall, the median Dice similarity coefficient was 0.66. Statistically significant differences were observed according to the level of expertise (better agreement for J and E, worse for S); the axillary level (better agreement for L1 and L4, worse for L3); the patient (better agreement for P1, worse for P3). Statistically significant differences in contouring were found in 18% of the inter-center comparison. Less than a half of the centers could claim to have a good agreement between the internal ROs.
Conclusions:
The overall intra-institute and inter-institute agreement was moderate. Central lymph-node levels were the most critical and variability increased as the complexity of the patient's anatomy increased. These findings might have an effect on the interpretation of results from multicenter and even mono-institute studies.
... The atlas is sometimes used to evaluate other things, commonly the quality of a segmentation like in [39,40] or the accuracy of models of light propagation within the head [41] but the atlas itself is rarely, but occasionally [42] assessed. First, its final quality is related to the initial segmentation of the shapes used to build it and, even in manual segmentation procedures, with the protocols of organ or lesion delineation [43]. It is not clear which quality indexes should be taken and normally those used to evaluate the quality of the geometric coregistration are used for atlases, too. ...
Background
Anatomical atlases are 3D volumes or shapes representing an organ or structure of the human body. They contain either the prototypical shape of the object of interest together with other shapes representing its statistical variations (statistical atlas) or a probability map of belonging to the object (probabilistic atlas). Probabilistic atlases are mostly built with simple estimations only involving the data at each spatial location.
Results
A new method for probabilistic atlas construction that uses a generalized linear model is proposed. This method aims to improve the estimation of the probability to be covered by the liver. Furthermore, all methods to build an atlas involve previous coregistration of the sample of shapes available. The influence of the geometrical transformation adopted for registration in the quality of the final atlas has not been sufficiently investigated. The ability of an atlas to adapt to a new case is one of the most important quality criteria that should be taken into account. The presented experiments show that some methods for atlas construction are severely affected by the previous coregistration step.
Conclusion
We show the good performance of the new approach. Furthermore, results suggest that extremely flexible registration methods are not always beneficial, since they can reduce the variability of the atlas and hence its ability to give sensible values of probability when used as an aid in segmentation of new cases.
... However, in WBI treatment planning, since fatty breast and non-breast tissues have a similar electronic density, difficulties in differentiating between them hamper volume delineation. Consequently, significant inter-and intra-observer variability was reported [8][9][10][11][12]. ...
Background:
Whole breast irradiation after conserving surgery for breast cancer requires precise definition of the target volume. The standard approach uses computed tomography (CT) images. However, since fatty breast and non-breast tissues have similar electronic densities, difficulties in differentiating between them hamper breast volume delineation. To overcome this limitation the breast contour is defined by palpation and then radio-opaque wire is put around it before the CT scan. To optimize assessment of breast margins in the cranial, caudal, medial, lateral and posterior directions, the present study evaluated palpation and CT and determined whether ultrasound (US) provided any added value.
Methods:
Twenty consecutive patients were enrolled after they had provided informed consent to participating in this prospective study which was approved by the Regional Public Health Ethics Committee. Palpation and US defined breast margins and each contour was marked and outlined with a fine plastic wire. Breasts were then contoured on axial CT images using the breast window width (WW) and window level (WL) (401 and 750 Hounsfield Units -HU- respectively), at which setting the plastic wires were invisible. Then, the lung window function (WW 1601 HU; WL -300 HU) was inserted to visualize the plastic wires which were used as guidelines to contour the palpable and US breast volumes. As each wire had a different diameter, both volumes were easily defined on CT slices. Results were analyzed using descriptive statistics, percentage overlap and reproducibility measures (agreement and reliability).
Results:
Volumes: US gave the largest and palpation the smallest. Agreement was best between palpation and CT. Reliability was almost perfect in all correlations. Extensions: Cranial and posterior were highest with US and smallest with palpation. Agreement was best between palpation and CT in all extensions except the cranial. Since strong to almost perfect agreement emerged for all comparisons, reliability was high.
Conclusions:
US may be useful in defining the cranial and posterior extensions, mainly when tumours are localized there. This study demonstrates that the now standard radio-opaque wires around the palpable breast may not be needed in breast contouring.
... After the development of our institutional guidelines, other studies described their attempts to optimize nodal volume delineation in breast cancer patients (29,30,(35)(36)(37)(38). The Curie Institute group (29,35) defined easy, practical guidelines for delineating key structures in unenhanced CT scans. ...
... After the development of our institutional guidelines, other studies described their attempts to optimize nodal volume delineation in breast cancer patients (29,30,(35)(36)(37)(38). The Curie Institute group (29,35) defined easy, practical guidelines for delineating key structures in unenhanced CT scans. In routine clinical practice, this approach, which takes all international recommendations into account, shortened times, improved breast and lymph node contouring, and reduced interobserver variability (35). ...
Current advances in radiotherapy for breast cancer require knowledge of the anatomy of irradiated areas to minimize geographic miss and spare organs at risk. This study aimed at defining a contouring approach for supraclavicular (SC) and infraclavicular (IC) nodes after mastectomy or conservative surgery in patients with breast cancer.
In 15 patients, SC and IC nodes were contoured on computed tomography slices according to Madu et al and Dijkema et al. After analyzing relapse sites, as reported by Reed et al, our approach was defined. The 3 methods were compared in all patients, quantifying differences in contours by percentage overlap (PO).
In our approach, SC node delineation is similar to Madu et al in the ventral and medial landmarks, but includes the lateral SC nodes described by Dijkema et al. The lateral landmarks are the scalenus anterior and medius muscle lateral border and the clavicle. Dorsal boundaries are the scalenus anterior and medius muscle ventral and lateral surfaces and the subclavian artery ventral border. In IC node delineation, major differences emerged in cranial and dorsal limits which, in our approach, are the pectoralis minor muscle upper edge and the subclavian axillary artery ventral side. Our mean and median volumes and POs were between the other 2 methods.
This study contributes to standardizing draining node contouring, so as to reduce variability and minimize geographic miss.
