Impact of a contouring atlas on radiographer inter-observer variation in male pelvis radiotherapy

PURPOSE/OBJECTIVE

To determine the impact of a MR-based contouring atlas for male pelvis radiotherapy delineation on inter-observer variation to support radiographer led real-time magnetic resonance image guided adaptive radiotherapy (MRgART).

MATERIAL/METHODS

Eight RTTs contoured 25 MR images in the Monaco treatment planning system (Monaco 5.40.01), from 5 patients. The prostate, seminal vesicles, bladder, and rectum were delineated before and after the introduction of an atlas developed through multi-disciplinary consensus. Inter-observer contour variations (volume), time to contour and observer contouring confidence were determined at both time-points using a 5-point Likert scale. Descriptive statistics were used to analyse both continuous and categorical variables. Dice similarity coefficient (DSC), Dice-Jaccard coefficient (DJC) and Hausdorff distance were used to calculate similarity between observers.

RESULTS

Although variation in volume definition decreased for all structures among all observers post intervention, the change was not statistically significant. DSC and DJC measurements remained consistent following the introduction of the atlas for all observers. The highest similarity was found in the bladder and prostate whilst the lowest was the seminal vesicles. The mean contouring time for all observers was reduced by 50% following the introduction of the atlas (53 to 27 minutes, p=0.01). For all structures across all observers, the mean contouring confidence increased significantly from 2.3 to 3.5 out of 5 (p=0.02).

CONCLUSION

Although no significant improvements were observed in contour variation amongst observers, the introduction of the consensus-based contouring atlas improved contouring confidence and speed; key factors for a real-time RTT-led MRgART.

Examining the impact of the device used for contouring in saving time and increasing the ease of contouring patients in radiotherapy treatment

INTRODUCTION/BACKGROUND

This study was designed to investigate the amount of time saved and the degree of contour difficulty between the two methods of contouring, mouse/keyboard, versus touch screen/stylus in radiotherapy.

METHODS

Each of 94 patients consisting of 26 breast cancer cases, 24 lymph nodes cases, 25 rectal cancer cases, and 19 heart cases has been contoured twice. One with a mouse/keyboard, and the next one with the touch screen/stylus. Three radiation oncologists participated in this study. Contouring information including measured time, estimated time spent, volume of contour performed and organ contoured are recorded. To evaluate the differences between the contouring methods, the results regarding target volume and time to completion were analyzed using two-way robust ANOVA. Ease of use and contouring difficulty were compared for differences in distribution of the response choices between the groups using Pearson chi-square test.

RESULTS

In this study, 94 clinical cases were studied. The average time required for contouring with the touch screen/stylus method was half the time needed for contouring patients with the mouse/keyboard method. The reduction in the time in breast cancer cases was the highest (48.2%) and the lowest in head and neck cancer cases (32.4%). In comparing the contoured volumes, no significant difference was observed between the two methods. the mean estimated time reported by the radiation oncologist in the mouse/keyboard method was 5.6 minutes longer and, in the touch screen/stylus method, was 3.9 minutes less than the actual measured time.

CONCLUSIONS

All the measured and analyzed variables show the superiority of contouring with the touch screen/stylus method and reduced the time required for patient contouring by an average of 50%.

Evaluating Efficacy and Complications of Contour Intrasaccular Device in Cerebral Aneurysm Management: A Multicenter Analysis

BACKGROUND

Intrasaccular devices provide a method for treating complex aneurysms without leaving metallic materials in the parent artery. Compared to other well-studied devices in neurointervention, the Contour device is relatively new as an intrasaccular flow diverter. This study examines its use in cases of incidental aneurysms and its application in the acute treatment of ruptured aneurysms. Additionally, it covers potential complications that may arise and methods for prevention.

METHODS

We conducted a retrospective analysis of 25 patients who underwent treatment with the Contour device at 3 hospital centers. We collected data related to age, gender, baseline modified Rankin Scale, personal habits, medical history, procedure details, and angiographic results according to the Woven endobridge occlusion scale.

RESULTS

A total of 15 patients (65.5%) achieved a satisfactory angiographic result (grade 0-0') 1 year after embolization. Contrast stagnation was observed in 14 patients (58.3%). Intraprocedural complications, such as device displacement, were documented in 3 patients (12%), while 2 patients (8%) had aggregates attached to the device. Regarding late complications, 5 patients (20%) experienced device displacement and 1 patient had a minor stroke (4%). Retreatment was necessary for 3 patients (12%), involving a flow diverter, stenting, and coiling.

CONCLUSIONS

In summary, the Contour device offers a viable option for treating complex aneurysms. While initial results are promising, it is crucial to acknowledge a learning curve to minimize complications and achieve satisfactory angiographic results without the need for additional treatments.

Radiation therapy for cT1-2 carcinoma of the palatine tonsil diagnosed via a simple tonsillectomy: Dosimetry and patterns of care in the IMRT era

OBJECTIVE

Small carcinomas of the palatine tonsil are often diagnosed via simple tonsillectomy, a maneuver with non-therapeutic intent. Herein, practice patterns for this unique situation are evaluated.

PATIENTS AND METHODS

A retrospective review was performed across 10 facilities to identify patients with cT1-2 squamous carcinomas of the tonsil diagnosed by simple tonsillectomy between 2010 and 2018. Patients who received curative-intent intensity modulated radiotherapy (IMRT) without additional surgery were included. Target volumes were reviewed, and cumulative incidences of local failure and severe late dysphagia were calculated.

RESULTS

From 638 oropharyngeal patients, 91 were diagnosed via simple tonsillectomy. Definitive IMRT with no additional surgery to the primary site was utilized in 57, and three with gross residual disease were excluded, leaving 54 for analysis. Margins were negative in 13%, close (<5 mm) in 13%, microscopically positive in 61%, and not reported in 13%. Doses typically delivered to gross disease (68-70.2 Gy in 33-35 fx or 66 Gy/30 fx) were prescribed to the tonsil bed in 37 (69%). Sixteen patients (29%) received doses from 60 to 66 Gy (≤2 Gy/fx) and one received 50 Gy (2 Gy/fx). No local failures were observed. One late oropharyngeal soft tissue ulcer occurred, treated conservatively (grade 2). At five years, the cumulative incidence of severe late dysphagia was 17.4% (95% CI 6.1-28.8%).

CONCLUSION

Small tonsil carcinomas diagnosed by simple tonsillectomy represent a niche subset with favorable oncologic outcomes. Regardless, radiation oncologists tend to deliver full-dose to the tonsil bed. The necessity of this routine could be questioned in the modern era.

Rhythm contour drives musical memory

Listeners' use of contour information as a basis for memory of rhythmic patterns was explored in two experiments. Both studies employed a short-term memory paradigm in which listeners heard a standard rhythm, followed by a comparison rhythm, and judged whether the comparison was the same as the standard. Comparison rhythms included exact repetitions of the standard, same contour rhythms in which the relative interval durations of successive notes (but not the absolute durations of the notes themselves) were the same as the standard, and different contour rhythms in which the relative duration intervals of successive notes differed from the standard. Experiment 1 employed metric rhythms, whereas Experiment 2 employed ametric rhythms. D-prime analyses revealed that, in both experiments, listeners showed better discrimination for different contour rhythms relative to same contour rhythms. Paralleling classic work on melodic contour, these findings indicate that the concept of contour is both relevant to one's characterization of the rhythm of musical patterns and influences short-term memory for such patterns.

Parapharyngeal Space Tumors: Our Experience

Para-pharyngeal space (PPS) tumors include an heterogeneous group of neoplasms, accounting for approximatively 0.5-1.5% of all head and neck tumors. Management of these neoplasms requires a careful diagnostic workout and an appropriate surgical approach to obtain good outcomes associated with minimal aesthetic drawbacks. In this study we investigated clinical onset, histologic features, surgical treatment outcomes, peri operative complications and follow up of 98 patients treated for PPS tumors in our Centre between 2002 and 2021. Furthermore, we reviewed our preliminary experience of preoperative embolization of hyper vascular PPS tumors trough SQUID12, an ethylene vinyl alcohol copolymers (EVOH) which exhibits many advantages over other embolic agents, due to its better devascularization rate and lower risk of systemic complications. Our data support the hypothesis that transoral surgery scenario should be significantly revised, as it could represent a valid treatment for tumors located in lower and prestyloyd portion of PPS. Moreover, SQUID12, a novel embolization agent, may be a very promising choice for PPS hyper vascularized tumors, ensuring higher devascularization rate, safer procedures and lower risk of systemic dispersion compared to traditional Contour treatment.

The influence of a contoured seating base on pressure distribution and discomfort

PURPOSE

This research paper examines how contouring of a wheelchair seating base can help prevent pressure sores by distributing pressure over the buttocks. Contouring wheelchair cushioning is already done to some extent and has proved to be beneficial for pressure distribution. We researched the effect of contouring the seating base, and whether contouring the seating base affects effectiveness in pressure distribution and perceived discomfort.

MATERIALS & METHODS

13 healthy participants performed a within-subject experiment with three differently contoured seating bases. Perceived comfort and seating pressure were measured for each condition.

RESULTS

Results indicate that a more contoured base is positive for both comfort and increased pressure distribution.

CONCLUSIONS

Contoured seating bases can provide increased comfort and improved pressure distribution over flat seating bases. Future research should examine the effect of contouring on stability, as well as compare the effects of contoured seating bases and contoured cushions.Implications for rehabilitationWe evaluated the comfort and pressure characteristics of three differently contoured hard seating bases for a wheelchair. The outcomes of the research shows that providing increased contour to seatings could be beneficial to reduce pressure peaks in the buttocks.Contour in the seating is conventionally created by shaping the cushions, this research shows the possibility of using a hard base underneath a cushion to create the desired contour.

Intensity-modulated radiotherapy does not induce volumetric changes of the Bichat fat pad in nasopharyngeal cancer

PURPOSE

To evaluate morphological and functional changes in the Bichat fat pad (BFP) after curative concurrent chemoradiotherapy in nasopharyngeal cancer (NPC) patients.

METHODS

We retrospectively analyzed the volumetric, metabolic, and dosimetry parameters of BFPs in 7 NPC patients who underwent intensity-modulated radiotherapy (IMRT) between 2015 and 2020. Inclusion criteria were i) histologically confirmed diagnosis of NPC, ii) follow-up period of at least 12 months, iii) no history of previous irradiation or surgery in the maxillofacial area, and ìv) availability of pre- and posttreatment MRI and ¹⁸F‑FDG PET-CT performed in our Institution. All patients had stage III-IVA disease (n = 7) and received platinum-based chemotherapy. Planned doses in 30 daily fractions/5 days per week were 66 Gy (2.2 Gy/die 5 days/week) to the gross tumor volume, 66 Gy (2.1-2.2 Gy/die 5 days/week) to the gross nodal volume, 60 Gy (2 Gy/die 5 days week) to clinical target volume (CTV)1, and 54 Gy (1.8 Gy/die 5 days/week) to CTV2. All patients completed the planned radiotherapy course in a median time of 42 days (range 42-43). Relationships between BFP volumes and the following DVH parameters were evaluated: mean dose, maximum dose (Dmax), and percentage of BFP volume receiving more than 5 to 65 Gy (V5 to V65).

RESULTS

The pre-RT volumes of the left and right BFPs were 12.24 cc (range 6.51-20.01 cc) and 11.55 cc (range 5.78-17.53 cc), respectively. The mean volumes of left BFP_PRE and BFP_POST were 12.24 cc (range 6.51-20.01cc) and 13.85 cc (range 7.54-20.21 cc), respectively, with no significant statistical differences (P > 0.05). No statistically significant correlations were found between dosimetry features and BFP volumetric changes (all P > 0.05).

CONCLUSION

Our original results showed that chemoradiotherapy does not induce significant volumetric changes of the BFP. Further investigations are needed to evaluate the effects of higher radiation doses on BFP. This is the first real-world study on this issue.

Vehicular traffic noise modelling of urban area-a contouring and artificial neural network based approach

Road traffic vehicular noise is one of the main sources of environmental pollution in urban areas of India. Also, steadily increasing urbanization, industrialization, infrastructures around city condition causes health risks among the urban populations. In this study, we have explored noise descriptors (L₁₀, L₉₀, L_dn, LNI, TNI, NC), contour plotting and find the suitability of artificial neural networks (ANN) for the prediction of traffic noise all around the Dhanbad township in 15 monitoring stations. In order to develop the prediction model, measuring noise levels of five different hours, speed of vehicles, and traffic volume in every monitoring point have been studied and analyzed. Traffic volume, percent of heavy vehicles, speed, traffic flow, road gradient, pavement, road side carriageway distance factors were taken as input parameter, whereas L_Aeq as output parameter for formation of neural network architecture. As traffic flow is heterogenous which mainly contains 59%, two wheelers and different vehicle specifications with varying speeds also affect driving and honking behavior which constantly changing noise characteristics. From radial noise diagrams shown that average noise levels of all the stations beyond permissible limit and the highest noise levels were found at the speed of 50-55 km/h in both peak and non-peak hours. Noise descriptors clearly indicate high annoyance level in the study area. Artificial neural network with 7-7-5 formation has been developed and found as optimum due to its sum of square and overall relative error 0.858 and .029 in training and 0.458 and 0.862 in testing phase respectively. Comparative analysis between observed and predicted noise level shows very less deviation up to ± 0.6 dB(A) and the R² linear values are more than 0.9 in all five noise hours indicating the accuracy of model. Also, it can be concluded that ANN approach is much superior in prediction of traffic noise level to any other statistical method.

Evaluation of the contour of the pancreas: types and frequencies

PURPOSE

Pancreas contour variations can sometimes be misdiagnosed as mass lesions. This study aimed to evaluate normal pancreatic contour morphology, variations, frequency and the development of the uncinate process.

METHODS

Out of 1183 consecutive computed tomography images taken in our hospital for various reasons (e.g. malignity, donor), 899 suitable images were included in the study. The following variations were identified: globular, elongated or globular-elongated contours of the pancreas head, protrusions of the body-tail surfaces and globular, lobular, globular-lobular, tapered and bifid contours of the tail. Hypoplasia and aplasia of the uncinate process were identified. All images were evaluated retrospectively by two radiologists.

RESULTS

Of the 899 patients, 504 (56.1%) were males. The mean age of the patients was 53.9 ± 14.7 (range 18-89). Hypoplasia of the uncinate process was found in 72 (8%) patients; aplasia was seen in 11 (1.2%) patients. Thirty-one (3.5%) of the pancreatic head variations were globular, 49 (5.4%) elongated and three (0.3%) elongated-globular. In patients with pancreatic uncinate process developmental anomaly, contour variations were also detected in the head of the pancreas. The pancreatic body-tail showed protrusions anteriorly in 76 (8%) patients and posteriorly in 11 (1.2%) patients. Seventy-two (8%) of the pancreatic tail variations were globular, 39 (4.4%) were globular-lobular, 18 (2%) were tapered and 17 (1.8%) were bifid.

CONCLUSION

Patients with pancreatic uncinate process developmental anomaly also have contour variations in the head of the pancreas. Pancreatic uncinate process developmental anomaly was seen in 9.2%. Pancreatic tail contour variation was 16.2%. The pancreatic body-tail showed protrusion in 9.2% of patients.

Integration of contours defined by second-order contrast-modulation of texture

Boundaries in the visual world can be defined by changes in luminance and texture in the input image. A "contour integration" process joins together local changes into percepts of lines or edges. A previous study tested the integration of contours defined by second-order contrast-modulation. Their contours were placed in a background of random wavelets. Participants performed near chance. We re-visited second-order contour integration with a different task. Participants distinguished contours with "good continuation" from distractors. We measured thresholds in different amounts of external orientation or position noise. This gave two noise-masking functions. We also measured thresholds for contours with a baseline curvature to assess performance with more curvy targets. Our participants were able to discriminate the good continuation of second-order contours. Thresholds were higher than for first-order contours. In our modelling, we found this was due to multiple factors. There was a doubling of equivalent internal noise between first- and second-order contour integration. There was also a reduction in efficiency. The efficiency difference was only significant in our orientation noise condition. For both first- and second-order stimuli, participants were also able to perform our task with more curved contours. We conclude that humans can integrate second-order contours, even when they are curved. There is however reduced performance compared to first-order contours. We find both an impaired input to the integrating mechanism, and reduced efficiency seem responsible. Second-order contour integration may be more affected by the noise background used in the previous study. Difficulty segregating that background may explain their result.

Reconstructive trends and complications following parotidectomy: incidence and predictors in 11,057 cases

BACKGROUND

Parotidectomy is a common treatment option for parotid neoplasms and the complications associated with this procedure can cause significant morbidity. Reconstruction following parotidectomy is utilized to address contour deformity and facial nerve paralysis. This study aims to demonstrate national trends in parotidectomy patients and identify factors associated with adverse postoperative outcomes. This study includes the largest patient database to date in determining epidemiologic trends, reconstructive trends, and prevalence of adverse events following parotidectomy.

METHODS

A retrospective review was performed for parotidectomies included in the ACS-NSQIP database between January 2012 and December 2017. CPT codes were used to identify the primary and secondary procedures performed. Univariate and multivariate analysis was utilized to determine associations between pre- and perioperative variables with patient outcomes. Preoperative demographics, surgical indications, and common medical comorbidities were collected. CPT codes were used to identify patients who underwent parotidectomy with or without reconstruction. These pre- and perioperative characteristics were compared with 30-day surgical complications, medical complications, reoperation, and readmission using uni- and multivariate analyses to determine predictors of adverse events.

RESULTS

There were 11,057 patients who underwent parotidectomy. Postoperative complications within 30 days were uncommon (1.7% medical, 3.8% surgical), with the majority of these being surgical site infection (2.7%). Free flap reconstruction, COPD, bleeding disorders, smoking, and presence of malignant tumor were the strongest independent predictors of surgical site infection. Readmission and reoperation were uncommon at an incidence of 2.1% each. The strongest factors predictive of readmission were malignant tumor and corticosteroid usage. The strongest factors predictive of reoperation were free flap reconstruction, malignant tumor, bleeding disorder, and disseminated cancer. Surgical volume/contour reconstruction was relatively uncommon (18%). Facial nerve sacrifice was uncommon (3.7%) and, of these cases, only 25.5% underwent facial nerve reinnervation and 24.0% underwent facial reanimation.

CONCLUSIONS

There are overall low rates of complications, readmissions, and reoperations following parotidectomy. However, certain factors are predictive of adverse postoperative events and this data may serve to guide management and counseling of patients undergoing parotidectomy. Concurrent reconstructive procedures are not commonly reported which may be due to underutilization or underreporting.

Aesthetic sensitivity to curvature in real objects and abstract designs

The features of objects have a strong influence on how we evaluate, judge, approach, and behave toward them. People generally prefer complex, symmetric, balanced and curved designs. In addition to these general trends, however, there are substantial differences among people in what they like and prefer, and in the extent to which their preferences and choices are modulated by design features. Here we aimed to determine whether curvature in real objects and abstract designs influenced participants' preference to the same extent. We found that, in general, participants prefer real objects and abstract designs with curved contours. But we also uncovered a remarkable breadth of variation in individual preferences. Finally, our results show that people who are highly sensitive to curvature in real objects are also highly sensitive to curvature in abstract designs, and that people who are insensitive to curvature in one kind of stimulus are also insensitive to the other.

Microwave reflectometry for noninvasive imaging of skin abnormalities

In this paper, a microwave microscope is presented for characterization of skin abnormalities. A coplanar waveguide probe is designed and fabricated for high-resolution near-field imaging of the biological samples. Several simulations and measurement studies are described to present the capability of the proposed probe in identification of different tissues and the detection of fat masses at different depths. In addition, two methods are used to eliminate the measurement noise which is caused by non-targeted tissues. Then, the contours around the masses are obtained applying an edge detection method. The measurement results show that the proposed probe can detect the fat masses with amplitude contrast about 15 dB at a λ/10 (at 14.36 GHz) standoff distance. The proposed microscope is easy to fabricate, and provides a low-cost solution for fast and accurate skin cancer detection of abnormalities in human body such as early detection of small tumors in breast or skin cancers.

Contour of lingual surface in lower complete denture formed by polished surface impression

PURPOSE

The aim of this study was to analyze the shapes of lingual polished surfaces in lower complete dentures formed by polished surface impressions and to provide reference data for use when manufacturing edentulous trays and lower complete dentures.

MATERIALS AND METHODS

Twenty-six patients with mandibular edentulism were studied. After lower wax dentures were fabricated, wax was removed from the lingual side of the wax denture and a lingual polished surface impression was obtained with tissue conditioner. The definitive denture was scanned with a three-dimensional scanner, and scanned images were obtained. At the cross-sections of the lingual frenum, lateral incisors, first premolars, first molars, and anterior border of the retromolar pads, three points were marked and eight measurements were taken. The Kruskal-Wallis test and a post hoc analysis with the Mann-Whitney test were performed.

RESULTS

Each patient showed similar values for the same areas on the left and right sides without a statistically significant difference. The height of the contour of the lingual polished surface at the lingual frenum was halfway between the occlusal plane and lingual border, it moved gradually in a downward direction. The angle from the occlusal plane to the height of the contour of the lingual polished surface was increased as it progressed from the lingual frenum towards the retromolar pads.

CONCLUSION

The shape of the mandibular lingual polished surface was convex at the lingual frenum, lateral incisors and gradually flattened towards the first molars and retromolar pads.

3D surgical printing and pre contoured plates for acetabular fractures

We describe the methodical and possibilities of 3D surgical printing in preoperative planning of acetabular fractures showing a case of a 45-year-old with an associated transverse fracture of the left acetabulum with posterior wall fracture, with multiple fragments, and posterior ipsilateral hip dislocation, defending the do it your-self mode.

A systematic comparison between visual cues for boundary detection

The detection of object boundaries is a critical first step for many visual processing tasks. Multiple cues (we consider luminance, color, motion and binocular disparity) available in the early visual system may signal object boundaries but little is known about their relative diagnosticity and how to optimally combine them for boundary detection. This study thus aims at understanding how early visual processes inform boundary detection in natural scenes. We collected color binocular video sequences of natural scenes to construct a video database. Each scene was annotated with two full sets of ground-truth contours (one set limited to object boundaries and another set which included all edges). We implemented an integrated computational model of early vision that spans all considered cues, and then assessed their diagnosticity by training machine learning classifiers on individual channels. Color and luminance were found to be most diagnostic while stereo and motion were least. Combining all cues yielded a significant improvement in accuracy beyond that of any cue in isolation. Furthermore, the accuracy of individual cues was found to be a poor predictor of their unique contribution for the combination. This result suggested a complex interaction between cues, which we further quantified using regularization techniques. Our systematic assessment of the accuracy of early vision models for boundary detection together with the resulting annotated video dataset should provide a useful benchmark towards the development of higher-level models of visual processing.

Memory for pure tone sequences without contour

We presented pure tones interspersed with white noise sounds to disrupt contour perception in an acoustic short-term memory (ASTM) experiment during which we recorded the electroencephalogram. The memory set consisted of seven stimuli, 0, 1, 2, 3, or 4 of which were to-be-remembered tones. We estimated each participant׳s capacity, K, for each set size and measured the amplitude of the SAN (sustained anterior negativity, an ERP related to acoustic short-term memory). We correlated their K slopes with their SAN amplitude slopes as a function of set size, and found a significant link between performance and the SAN: a larger increase in SAN amplitude was linked with a larger number of stimuli maintained in ASTM. The SAN decreased in amplitude in the later portion of the silent retention interval, but the correlation between the SAN and capacity remained strong. These results show the SAN is not an index of contour but rather an index of the maintenance of individual objects in STM. This article is part of a Special Issue entitled SI: Auditory working memory.

Contextual modulation as de-texturizer

Contextual modulation refers to the effect of texture placed outside of a neuron's classical receptive field as well as the effect of surround texture on the perceptual properties of variegated regions within. In this minireview, we argue that one role of contextual modulation is to enhance the perception of contours at the expense of textures, in short to de-texturize the image. The evidence for this role comes mainly from three sources: psychophysical studies of shape after-effects, computational models of neurons that exhibit iso-orientation surround inhibition, and fMRI studies revealing specialized areas for contour as opposed to texture processing. The relationship between psychophysical studies that support the notion of contextual modulation as de-texturizer and those that investigate contour integration and crowding is discussed.