An atlas-based method to predict three-dimensional dose distributions for cancer patients who receive radiotherapy

Due to the complexity of advanced radiotherapy techniques, treatment planning process is usually time consuming and plan quality can vary considerably among planners and institutions. It is also impractical to generate all possible treatment plans based on available radiotherapy techniques and select the best option for a specific patient. Automatic dose prediction will be very helpful in these situations, while there were a few studies of three-dimensional (3D) dose prediction for patients who received radiotherapy. The purpose of this work was to develop a novel atlas-based method to predict 3D dose prediction and to evaluate its performance. Previously treated nineteen left-sided post-mastectomy breast cancer patients and sixteen prostate cancer patients were included in this study. One patient was arbitrarily chosen as the reference for each type of cancer and all the remaining patients\u27 computed tomography (CT) images and contours were aligned to it using deformable image registration (DIR). Deformable vector field (DVF) for each patient i (DVFi-ref) was used to deform the original 3D dose matrix of that patient. CT scan of a test patient was also registered with the same reference patient using DIR and both direct DVF (DVFtest-ref) and inverse DVF () were derived. Similarity of atlas patients to the test patient was determined based on the similarity of DVFtest-ref to atlas DVFs (DVFi-ref) and appropriate weighting factors were calculated. Patients\u27 doses in the atlas were deformed again using to transform them from the reference patient\u27s coordinates to the test patient\u27s coordinates and the final 3D dose distribution for the test patient was predicted by summing the weighted individual 3D dose distributions. Performance of our method was evaluated and the results revealed that the proposed method was able to predict the 3D dose distributions accurately. The mean dose difference between clinical and predicted 3D dose distributions were 0.9 ± 1.1 Gy and 1.9 ± 1.2 Gy for breast and prostate plans. The proposed dose prediction method can be used to improve planning quality and facilitate plan comparisons

Elevated Troponin in Patients with Intracerebral Hemorrhage

Troponin, a known marker for cardiac damage, also plays a role in predicting mortality and morbidity in patients with intracerebral hemorrhage (ICH). Elevated troponin levels have been noted in patients with ICH and studies have shown that such patients are more likely to experience adverse outcomes. The mechanism behind this is suggested to be the release of sympathetic hormones causing myocardial injury. The first differential that often comes to mind when a physician sees an elevated troponin level is a myocardial infarction (MI). In this paper, we present a case of a 54-year-old female who presented to the ED with nausea, vomiting, and severe headache with a troponin level of 47,000. This patient was initially treated with heparin for a non-ST elevation myocardial infarction (NSTEMI), but CT of the head showed ICH. Since part of the treatment protocol for a MI is heparin drip, not recognizing ICH as an underlying cause of MI could lead to worsened hemorrhage and death

Feasibility of generating synthetic CT from T1-weighted MRI using a linear mixed-effects regression model

Generation of synthetic computed tomography (sCT) for magnetic resonance imaging (MRI)-only radiotherapy is emerging as a promising direction because it can eliminate the registration error and simplify clinical workflow. The goal of this study was to generate accurate sCT from standard T1-weighted MRI for brain patients. CT and MRI data of twelve patients with brain tumors were retrospectively collected. Linear mixed-effects regression models were fitted between CT and T1-weighted MRI intensities for different segments in the brain. The whole brain sCTs were generated by combining predicted segments together. Mean absolute error (MAE) between real CTs and sCTs across all patients was 71.1 ±5.5 Hounsfield Unit (HU). Average differences in the HU values were 1.7 ±7.1 HU (gray matter), 0.9 ±5.1 HU (white matter), -24.7 ±8.0 HU (cerebrospinal fluid), 76.4 ±17.8 HU (bone), 20.9 ±20.4 HU (fat), -69.4 ±28.3 HU (air). A simple regression technique has been devised that is capable of producing accurate HU maps from standard T1-weighted MRI, and exceptionally low MAE values indicate accurate prediction of sCTs. Improvement is needed in segmenting MRI using a more automatic approach

The Influence of Acoustic Impedance Mismatch on Post-Stenotic Pulsed-Doppler Ultrasound Measurements in a Coronary Artery Model

Acoustic impedance mismatch at the fluid-wall interface was shown to affect the spectra from an intravascular Doppler device in an in vitro model with a diameter typical of human coronary arteries. Measurements were obtained first under Poiseuille flow conditions with impedance mismatches of 0%, 7% and 12%, and then under stenosed conditions for the 0% and 7% mismatch cases. For the zero mismatch case, the Doppler spectra could be readily interpreted in terms of fluid mechanical phenomena. When mismatch was present, the spectra from Poiseuille flow exhibited multiple peaks which could not be directly related to the velocity profile. Also, the spectra from stenosed flow with a mismatch of 7% were similar to those from the zero mismatch case but did not exhibit the specific flow-related features as clearly. These results indicate that the impedance mismatch alters the acoustic environment inside the model and that this causes artifact in the Doppler spectra

The acute and sub-chronic effects of cocoa flavanols on mood, cognitive and cardiovascular health in young healthy adults: a randomized, controlled trial.

Cocoa supplementation has been associated with benefits to cardiovascular health. However, cocoa\u27s effects on cognition are less clear. A randomized, placebo-controlled, double-blind clinical trial (n = 40, age M = 24.13 years, SD = 4.47 years) was conducted to investigate the effects of both acute (same-day) and sub-chronic (daily for four-weeks) 250 mg cocoa supplementation on mood and mental fatigue, cognitive performance and cardiovascular functioning in young, healthy adults. Assessment involved repeated 10-min cycles of the Cognitive Demand Battery (CDB) encompassing two serial subtraction tasks (Serial Threes and Sevens), a Rapid Visual Information Processing task, and a mental fatigue scale over the course of half an hour. The Swinburne University Computerized Cognitive Assessment Battery (SUCCAB) was also completed to evaluate cognition. Cardiovascular function included measuring both peripheral and central blood pressure and cerebral blood flow. At the acute time point, consumption of cocoa significantly improved self-reported mental fatigue and performance on the Serial Sevens task in cycle one of the CDB. No other significant effects were found. This trial was registered with the Australian and New Zealand Clinical Trial Registry (Trial ID: ACTRN12613000626763). Accessible via http://www.anzctr.org.au/TrialSearch.aspx?searchTxt=ACTRN12613000626763&ddlSearch=Registered

Patients After the Fontan Insights From Computational Fluid Dynamics

Reprints: Information about reprints can be found online a