A global method based on thin-plate splines for correction of geometric distortion: an application to fluoroscopic images

Quantitative analysis of biomedical images needs a careful correction of geometric distortion. To avoid the discontinuities of the local correction techniques and achieve good accuracy in the presence of global and local distortion, a novel global correction technique based on thin-plate splines is proposed. The technique approximates the grid points by a thin plate minimizing the weighted sum of the bending energy and the mean squared residual errors. The method proposed is compared with three traditional correction techniques: two local and one global. One local technique is linear and takes into account translation, rotation, and scaling, the other is nonlinear and includes skewing. The global technique is based on a two-dimensional polynomial model. Computer-based simulations and experimental tests on fluoroscopic images were carried out. The local techniques were sensitive to both sigmoidal and radial distortion. The polynomial and thin-plate splines global techniques were found sensitive only to sigmoidal distortion and to radial distortion, respectively. The two global techniques showed better performances with respect to any local on synthetic and real images. Where the distortion is predominantly radial or high computational efficiency is required, the polynomial global correction technique should be preferred. Where the distortion has a local nature or is predominantly sigmoidal, the thin-plate splines global correction technique should be chosen.     

Validation of contour-driven thin-plate splines for tracking fraction-to-fraction changes in anatomy and radiation therapy dose mapping

The goal of this study is to validate a deformable model using contour-driven thin-plate splines for application to radiation therapy dose mapping. Our testing includes a virtual spherical phantom as well as real computed tomography (CT) data from ten prostate cancer patients with radio-opaque markers surgically implanted into the prostate and seminal vesicles. In the spherical mathematical phantom, homologous control points generated automatically given input contour data in CT slice geometry were compared to homologous control point placement using analytical geometry as the ground truth. The dose delivered to specific voxels driven by both sets of homologous control points were compared to determine the accuracy of dose tracking via the deformable model. A 3D analytical spherically symmetric dose distribution with a dose gradient of approximately 10% per mm was used for this phantom. This test showed that the uncertainty in calculating the delivered dose to a tissue element depends on slice thickness and the variation in defining homologous landmarks, where dose agreement of 3-4% in high dose gradient regions was achieved. In the patient data, radio-opaque marker positions driven by the thin-plate spline algorithm were compared to the actual marker positions as identified in the CT scans. It is demonstrated that the deformable model is accurate (approximately 2.5 mm) to within the intra-observer contouring variability. This work shows that the algorithm is appropriate for describing changes in pelvic anatomy and for the dose mapping application with dose gradients characteristic of conformal and intensity modulated radiation therapy.     

Using a priori structural information from magnetic resonance imaging to investigate the feasibility of prostate diffuse optical tomography and spectroscopy: a simulation study

Implementation of diffuse optical tomography (DOT) for prostate cancer is challenging because the prostate is a deep-seated organ. We investigated whether diffuse optical tomography (DOT) and spectroscopy could be applied to monitor the physiology of prostate cancer using a small probe that could be placed endorectally. We manually segmented the prostate, the intraprostatic tumor, and the rectum using data from endorectal magnetic resonance imaging. These structures were reconstructed and meshed with tetrahedral finite elements in three dimensions. A 2 x 4 cm probe that has ten sources and 52 detectors were placed to face the anterior wall of the rectum in our simulation. Optical properties of the organs were obtained from the literature in the near infrared regime. Diffusion approximation was used to simulate photon migration with finite element method. Five wavelengths were used to simulate tissue absorption with realistic water, oxy- and deoxyhaemoglobin concentrations in the prostate. We combined a global search based on genetic algorithm with gradient-driven local search methods to fit the simulated data. Our results suggest that the optical properties and the concentrations of the chromophores of the prostate and the prostate cancer can be reliably recovered from the measurements using an endorectal probe. Prostate DOT is worth further investigation for clinical application.     

A feasibility study to investigate the acceptability and potential effectiveness of a telecare service for older people with chronic obstructive pulmonary disease

AimsTo investigate the feasibility, acceptance and potential effectiveness of delivering a telecare service on the health outcomes and hospital service utilization of community-dwelling patients with chronic obstructive pulmonary disease.MethodsEligible participants were older people, with moderate or severe chronic obstructive pulmonary disease, and who had been admitted to hospital at least once for exacerbation during the previous year. The participants were randomly assigned to the intervention or control group. Participants in the intervention group received a telecare device kit and they were asked to monitor their oxygen saturation, pulse rate and respiration rate using the device and to transmit the data to an online network platform. A medication and purse-lip breathing reminder with a feedback function is also provided in the device kit. A community nurse monitors changes in the physiological parameters and takes immediate action to address the patients’ needs. Participants in the control group received no other extra care. Study outcomes include user satisfaction, health-related quality of life, pulmonary function, hospital re-admission and use of emergency room services.ResultsTwenty-two participants in the intervention group and 18 in the control group were included in the analysis. The mean age of all 40 participants was 72.93 years. Overall, the participants in the intervention group expressed satisfaction with the telecare service. Some patients reported difficulty in reading the screen of the mobile phone and manipulating the tiny key-in buttons. No significant differences were found between the two time points (baseline and post-test period) with regard to health-related quality of life. No significant differences in pulmonary function and in the number of emergency department visits and hospital re-admissions between the study groups were found.ConclusionThe high level of user satisfaction indicated the feasibility of conducting a large-scale randomized control trial to evaluate the effects of a telecare service on health outcomes of patients with chronic obstructive pulmonary disease.     

A feasibility study of using conventional jaws to deliver IMRT plans in the treatment of prostate cancer

The aim of this study is to investigate the feasibility of using conventional jaws to deliver inverse planned intensity-modulated radiotherapy (IMRT) plans for patients with prostate cancer. For ten patients, each had one three-dimensional conformal plan (3D plan) and seven inverse IMRT plans using direct aperture optimization. For IMRT plans using conventional jaws (JO plans), the number of apertures per beam angle was set from two to seven while three apertures per beam angle were set for the multi-leaf collimator (MLC) plans. To evaluate each planning method, we compared average dose volume histograms (DVH), the conformal index (COIN), total number of segments and total number of monitor units. Among the JO plans with the number of apertures per beam angle varying from two to seven, no difference was observed in the average DVHs, and the plan conformal index became saturated after four apertures per beam angle. Subsequently, JO plans with four apertures per beam angle (JO-4A) were compared with 3D and MLC plans. Based on the average DVHs, no difference was found among 3D, JO-4A and MLC plans with regard to the planning target volume and rectum, but the DVHs for the bladder and penile bulb were significantly better with inverse IMRT plans than those with 3D plans. When compared with the plan conformity, the average COIN values for 3D, JO-4A and MLC plans were 0.61 +/- 0.07, 0.73 +/- 0.05 and 0.83 +/- 0.05, respectively. In conclusion, inverse IMRT plans using conventional jaws are clinically feasible, achieving better plan quality than 3D-CRT plans.     

Mutual information based CT registration of the lung at exhale and inhale breathing states using thin-plate splines

The advent of dynamic radiotherapy modeling and treatment techniques requires an infrastructure to weigh the merits of various interventions (breath holding, gating, tracking). The creation of treatment planning models that account for motion and deformation can allow the relative worth of such techniques to be evaluated. In order to develop a treatment planning model of a moving and deforming organ such as the lung, registration tools that account for deformation are required. We tested the accuracy of a mutual information based image registration tool using thin-plate splines driven by the selection of control points and iterative alignment according to a simplex algorithm. Eleven patients each had sequential CT scans at breath-held normal inhale and exhale states. The exhale right lung was segmented from CT and served as the reference model. For each patient, thirty control points were used to align the inhale CT right lung to the exhale CT right lung. Alignment accuracy (the standard deviation of the difference in the actual and predicted inhale position) was determined from locations of vascular and bronchial bifurcations, and found to be 1.7, 3.1, and 3.6 mm about the RL, AP, and IS directions. The alignment accuracy was significantly different from the amount of measured movement during breathing only in the AP and IS directions. The accuracy of alignment including thin-plate splines was more accurate than using affine transformations and the same iteration and scoring methodology. This technique shows promise for the future development of dynamic models of the lung for use in four-dimensional (4-D) treatment planning.     

Anatomical study to investigate the feasibility of pedicled nerve, free vessel gastrocnemius muscle transfer for restoration of biceps function.

A challenging problem is the patient with a total brachial plexus injury with nerve root avulsions. In these patients nerve repair is not possible and no local functioning muscles are available for transfer. Current techniques involve either nerve repair using donor nerves from the contralateral limb or free muscle transfer neurotized by intercostal nerves. The problem with both these techniques is that they are dependent on neural regeneration, which is imperfect. To overcome the problem we propose a technique of transferring a distant muscle whilst retaining its neural supply. Gastrocnemius is a strong muscle and one suitable for free tissue transfer. This study assessed the possibility of transferring gastrocnemius on its neural supply by determining the length of nerve available and whether it was possible to dissect the nerve to gastrocnemius from the main body of the sciatic nerve. We found that the latter was possible, and that the length of dissected nerve would allow transfer of the innervated muscle from the calf to the axilla.     

A feasibility study of a robot manipulator for the disabled

Two of the major causes of death and disability in the preterm newborn of the developed nations are cerebral ischaemia and intraventricular haemorrhage [1]. It is estimated that intraventricular haemorrhage develops in 40–50% of infants with a birthweight of 1500 g or less [2] but precisely how many individuals are affected by haemorrhage, or how many cases of disability are antedated by cerebral ischaemia, is not known because of the lack of effective low-cost instruments for the continuous, or at least frequent, assessment of cerebral metabolic status in the high-risk individual. In the future, however, fibre-optic-based spectraphotometric techniques for the measurement of cerebral redox state may provide low-cost, portable instruments for the noninvasive assessment of cerebral metabolism during the intensive care of the neonate.     

A feasibility study of a robot manipulator for the disabled

A robotic manipulator system appears to offer much potential for a severely handicapped person who has little or no hand function. Existing environmental control systems fulfil an important role, but are limited to preselected tasks. The robotic system described here aims to overcome such limitations by providing a user-controlled manipulative device, which is not restricted to preselected tasks. The paper describes the development of a system based on a relatively cheap desk-top mounted robotic device controlled by a microcomputer, in order to investigate the feasibility of such a system. The problems which have been encountered are the provision of user input commands from a person with limited control function, and also the progression from general control of the robot to the performing of useful domestic tasks. The paper also describes and discusses the results of a user survey and user trials.     

A pilot study to investigate the use of installment dispensing as a method of reducing drug wastage owing to adverse drug reactions.

A new method of dispensing prescribed medicines that are to be taken for longer than two weeks was investigated. It was found to reduce drug wastage and produce savings in the drugs bill. The scheme was generally well liked by patients, doctors, and pharmacists.     

Approach to antihypertensive adherence: a feasibility study on the use of student health coaches for uninsured hypertensive adults

Despite pharmacologic advances, medication non-adherence continues to challenge primary care providers in blood pressure (BP) management. Medical, nursing and pharmacy students (n=11) were recruited and trained as health coaches for uninsured, hypertensive patients (n=25) of a free clinic in an uncontrolled open trial. Pre-post analysis was conducted on BP, medication adherence, frequency of home BP monitoring, and health behavior (eg, diet, exercise). Patient satisfaction and feasibility of a student coach model was qualitatively evaluated. In the 12 patients who completed the intervention, an increase in medication adherence as measured by the Brief Medication Questionnaire was observed (P<.01), with a 11 mmHg reduction in systolic BP (P=.03). Qualitative data showed patient satisfaction with the intervention and other health behavior change. This feasibility study shows use of student health coaches to combat medication non-adherence in uninsured, hypertensive adults is promising.     

A feasibility study for the newborn screening of spinal muscular atrophy

PurposeThe natural history of spinal muscular atrophy suggests that for maximum effect, therapeutics will need to be administered in the earliest phases of the disease. This will require the adoption of techniques for the genetic analysis of affected individuals at the newborn stage. Our objective was to examine the feasibility surrounding the newborn screening for spinal muscular atrophy.MethodsWe investigated the application of real-time polymerase chain reaction technology for newborn screening. A multiplex assay was designed to identify homozygous deletions in SMN1 exon 7 and validated using 266 samples with defined SMN1 and SMN2 copy numbers. Sensitivity and specificity were then evaluated as part of a newborn screening strategy using DNA from 153 blood spots.ResultsReal-time technology validation demonstrated correct exclusion of all normal and carrier samples, and identified the homozygous SMN1 exon 7 deletions in all 32 affected samples. In the series of blood spots, all 59 affected samples were correctly identified yielding an analytic sensitivity of 100%; 56 normal and 39 carrier samples were correctly excluded yielding an analytic specificity of 100% for this blood spot series.ConclusionWe demonstrate that effective molecular technology exists and that ethics may soon warrant the newborn screening of spinal muscular atrophy.     

The use of graph theory techniques to investigate genealogical structure

The correspondence between a graph and a genealogy is used toapply techniques from the field of graph theory to genetic epidemiology.A method is described for discarding the individuals and marriageswhich contribute to the size but not to the complexity of agenealogy. The ‘max-flow min-cut’ algorithm is extendedto break large genealogies into two smaller, less complicatedcomponents. These techniques are illustrated using both artificialand real pedigrees.     

A study of junior doctors to investigate the factors that influence career decisions.

Both pre-registration house officers and general practitioner (GP) registrars agree on several desirable and undesirable factors that define their ideal career. These relate to fulfilling clinical work and preservation of a meaningful personal life. Many young doctors regret their choice of medicine as a career because of poor job conditions and stress and perceive career advice as inadequate. GP's influence over junior doctors at the time of their career decision making is very limited compared with that of consultants.     

A prospective study of the use of alternative therapies by men with localized prostate cancer

Although the use of alternative therapies is highly prevalent amongst men with prostate cancer, research about the predictors of such use is limited. The current study aimed to describe prospectively the use of alternative therapies by men diagnosed with localized prostate cancer and identify predictors of alternative therapy use. In all, 111 men newly diagnosed with localized prostate cancer (93% response) were recruited to the study prior to treatment. Men's use of alternative therapies and psychological variables including: psychological distress, orientation to health care, decisional conflict, and health locus of control, were assessed at three time points-(1) before treatment; (2) 2 months after completion of treatment; and (3) 12 months after completion of treatment. Demographic information was also obtained. The percentage of men using alternative therapies was 25, 17 and 14% before treatment, 2 and 12 months after treatment, respectively. In general, the most commonly used therapies were dietary changes, vitamins and herbal and nutrient remedies. Alternative therapy use was not related to final treatment choices. Before treatment, men who used alternative therapies were more uncertain about prostate cancer compared to men who were not using these therapies. Men who were using alternative therapies 12 months after treatment were less psychologically distressed that men who were not using these therapies. Health locus of control and orientation to health care were not found to be related to men's use of alternative therapies. In conclusion, men's use of alternative therapies after localized prostate cancer varied across time in terms of the incidence of use, the types of therapies used, and the psychological correlates of therapy use. Informational support that targets uncertainty about prostate cancer may assist men at diagnosis who are considering alternative therapy use. The potential for alternative therapies to have a supportive function in patient care requires further investigation.     

An experimental feasibility study on the use of scattering foil free beams for modulated electron radiotherapy

The potential benefit of using scattering foil free beams for delivery of modulated electron radiotherapy is investigated in this work. Removal of the scattering foil from the beamline showed a measured bremsstrahlung tail dose reduction just beyond R(p) by a factor of 12.2, 6.9, 7.4, 7.4 and 8.3 for 6, 9, 12, 16 and 20 MeV beams respectively for 2 × 2 cm(2) fields defined on-axis when compared to the clinical beamline. Monte Carlo simulations were matched to measured data through careful tuning of source parameters and the modification of certain accelerator components beyond the manufacturer's specifications. An accelerator model based on the clinical beamline and one with the scattering foil removed were imported into a Monte Carlo-based treatment planning system (McGill Monte Carlo Treatment Planning). A treatment planning study was conducted on a test phantom consisting of a PTV and two distal organs at risk (OAR) by comparing a plan using the clinical beamline to a plan using a scattering foil free beamline. A DVH comparison revealed that for quasi-identical target coverage, the volume of each OAR receiving a given dose was reduced, thus reducing the dose deposited in healthy tissue.     

MRI-guided interstitial ultrasound thermal therapy of the prostate: a feasibility study in the canine model

The feasibility of MRI-guided interstitial ultrasound thermal therapy of the prostate was evaluated in an in vivo canine prostate model. MRI compatible, multielement interstitial ultrasound applicators were developed using 1.5 mm diameter cylindrical piezoceramic transducers (7 to 8 MHz) sectored to provide 180 degrees of angular directional heating. Two in vivo experiments were performed in canine prostate. The first using two interstitial ultrasound applicators, the second using three ultrasound applicators in conjunction with rectal and urethral cooling. In both experiments, the applicators were inserted transperineally into the prostate with the energy directed ventrally, away from the rectum. Electrical power levels of 5-17 W per element (approximately 1.6-5.4 W acoustic output power) were applied for heating periods of 18 and 48 min. Phase-sensitive gradient-echo MR imaging was used to monitor the thermal treatment in real-time on a 0.5 T interventional MRI system. Contrast-enhanced T1-weighted images and vital-stained serial tissue sections were obtained to assess thermal damage and correlate to real-time thermal contour plots and calculated thermal doses. Results from these studies indicated a large volume of ablated (nonstained) tissue within the prostate, extending 1.2 to 2.0 cm from the applicators to the periphery of the gland, with the dorsal margin of coagulation well-defined by the applicator placement and directionality. The shape of the lesions correlated well to the hypointense regions visible in the contrast-enhanced T1-weighted images, and were also in good agreement with the contours of the 52 degrees C threshold temperature and t43 > 240 min. This study demonstrates the feasibility of using directional interstitial ultrasound in conjunction with MRI thermal imaging to monitor and possibly control thermal coagulation within a targeted tissue volume while potentially protecting surrounding tissue, such as rectum, from thermal damage.