The potential impact of CT-MRI matching on tumor volume delineation in advanced head and neck cancer

To study the potential impact of the combined use of CT and MRI scans on the Gross Tumor Volume (GTV) estimation and interobserver variation. Four observers outlined the GTV in six patients with advanced head and neck cancer on CT, axial MRI, and coronal or sagittal MRI. The MRI scans were subsequently matched to the CT scan. The interobserver and interscan set variation were assessed in three dimensions. The mean CT derived volume was a factor of 1.3 larger than the mean axial MRI volume. The range in volumes was larger for the CT than for the axial MRI volumes in five of the six cases. The ratio of the scan set common (i.e., the volume common to all GTVs) and the scan set encompassing volume (i.e., the smallest volume encompassing all GTVs) was closer to one in MRI (0.3-0.6) than in CT (0.1-0.5). The rest volumes (i.e., the volume defined by one observer as GTV in one data set but not in the other data set) were never zero for CT vs. MRI nor for MRI vs. CT. In two cases the craniocaudal border was poorly recognized on the axial MRI but could be delineated with a good agreement between the observers in the coronal/sagittal MRI. MRI-derived GTVs are smaller and have less interobserver variation than CT-derived GTVs. CT and MRI are complementary in delineating the GTV. A coronal or sagittal MRI adds to a better GTV definition in the craniocaudal directio

Movement of Ericaphis fimbriata (Hemiptera: Aphididae) apterae on blueberry

Blueberry scorch Virus is a new and important pathogen of blueberry in British Columbia, Canada of which the blueberry-infesting aphid Ericaphis fimbriata is a known Vector. In a study of the movement of apterous E. fimbriata, significantly more aphids fell when one ladybird beetle was added to E. fimbriata infested blueberry branches than when zero, two, or four were added. Similar numbers of aphids fell in the presence or absence of beetles at low aphid density (10-30 aphids per terminal), but more fell in the presence of beetles at high aphid density (50-70 aphids per terminal). The time taken for aphids to move a minimum distance of 60 cm off infested plants onto uninfested plants decreased with increasing aphid density which has important implications for the spread of the Virus

99mTc Hynic-rh-Annexin V scintigraphy for in vivo imaging of apoptosis in patients with head and neck cancer treated with chemoradiotherapy

PURPOSE: The purpose of this study was to determine the value of (99m)Tc Hynic-rh-Annexin-V-Scintigraphy (TAVS), a non-invasive in vivo technique to demonstrate apoptosis in patients with head and neck squamous cell carcinoma. METHODS: TAVS were performed before and within 48 h after the first course of cisplatin-based chemoradiation. Radiation dose given to the tumour at the time of post-treatment TAVS was 6-8 Gy. Single-photon emission tomography data were co-registered to planning CT scan. Complete sets of these data were available for 13 patients. The radiation dose at post-treatment TAVS was calculated for several regions of interest (ROI): primary tumour, involved lymph nodes and salivary glands. Annexin uptake was determined in each ROI, and the difference between post-treatment and baseline TAVS represented the absolute Annexin uptake: Delta uptake (DeltaU). RESULTS: In 24 of 26 parotid glands, treatment-induced Annexin uptake was observed. Mean DeltaU was significantly correlated with the mean radiation dose given to the parotid glands (r = 0.59, p = 0.002): Glands that received higher doses showed more Annexin uptake. DeltaU in primary tumour and pathological lymph nodes showed large inter-patient differences. A high correlation was observed on an inter-patient level (r = 0.71, p = 0.006) between the maximum DeltaU in primary tumour and in the lymph nodes. CONCLUSIONS: Within the dose range of 0-8 Gy, Annexin-V-scintigraphy showed a radiation-dose-dependent uptake in parotid glands, indicative of early apoptosis during treatment. The inter-individual spread in Annexin uptake in primary tumours could not be related to differences in dose or tumour volume, but the Annexin uptake in tumour and lymph nodes were closely correlated. This effect might represent a tumour-specific apoptotic respons

Unsupervised correspondence with combined geometric learning and imaging for radiotherapy applications

The aim of this study was to develop a model to accurately identify corresponding points between organ segmentations of different patients for radiotherapy applications. A model for simultaneous correspondence and interpolation estimation in 3D shapes was trained with head and neck organ segmentations from planning CT scans. We then extended the original model to incorporate imaging information using two approaches: 1) extracting features directly from image patches, and 2) including the mean square error between patches as part of the loss function. The correspondence and interpolation performance were evaluated using the geodesic error, chamfer distance and conformal distortion metrics, as well as distances between anatomical landmarks. Each of the models produced significantly better correspondences than the baseline non-rigid registration approach. The original model performed similarly to the model with direct inclusion of image features. The best performing model configuration incorporated imaging information as part of the loss function which produced more anatomically plausible correspondences. We will use the best performing model to identify corresponding anatomical points on organs to improve spatial normalisation, an important step in outcome modelling, or as an initialisation for anatomically informed registrations. All our code is publicly available at https://github.com/rrr-uom-projects/Unsup-RT-Corr-NetComment: Accepted in 3rd Workshop on Shape in Medical Imaging (ShapeMI 2023). This preprint has not undergone peer review or any post-submission improvements or correction

Modelling the effect of time varying organ deformations in head and neck cancer using a PCA model

Throughout the radiotherapy treatment process, geometrical changes in the patient often occur, e.g. organs differing in shape from that of the planning CT scan (pCT). This organ deformation leads to uncertainties in the dose distribution throughout the treatment course. We present a method to statistically model the time dependent effect of organ deformation on organ at risk (OAR) dose, with the aim of later incorporating it into advanced treatment planning methods i.e. probabilistic planning

Preadvies mossen en korstmossen.

Binnen het in OBN-kader uitgevoerd onderzoek was tot nu toe vaak aandacht voor de ruim 580 soorten mossen (inclusief variëteiten) en 800 soorten korstmossen die in Nederland voorkomen. Uit de Rode Lijsten blijkt dat er alle aanleiding is om meer aandacht te geven aan deze groepen. De achteruitgang van mossen en korstmossen speelt landelijk en in alle landschappen. Het Deskundigenteam Heuvellandschap heeft het preadvies begeleid namens alle deskundigenteams (droog zandlandschap, nat zandlandschap en beekdallandschap; rivierenlandschap; laagveenlandschap; zeekleilandschap; duin- en kustlandschap). Bij dit onderwerp zijn betrokken geweest: Universiteit Utrecht, Universiteit van Amsterdam, B ware (Radboud Universiteit), BLWG, Forestfun ecologisch advies en onderzoek, Alterr

Convex Structuring Element Decomposition for Single Scan Binary Mathematical Morphology

International audienceThis paper presents a structuring element decomposition method and a corresponding morphological erosion algorithm able to compute the binary erosion of an image using a single regular pass whatever the size of the convex structuring element. Similarly to classical dilation-based methods, the proposed decomposition is iterative and builds a growing set of structuring elements. The novelty consists in using the set union instead of the Minkowski sum as the elementary structuring element construction operator. At each step of the construction, already-built elements can be joined together in any combination of translations and set unions. There is no restrictions on the shape of the structuring element that can be built. Arbitrary shape decompositions can be obtained with existing genetic algorithms with an homogeneous construction method. This paper, however, addresses the problem of convex shape decomposition with a deterministic method