An evaluation of four CT-MRI co-registration techniques for radiotherapy treatment planning of prone rectal cancer patients

OBJECTIVES

MRI is the preferred staging modality for rectal carcinoma patients. This work assesses the CT-MRI co-registration accuracy of four commercial rigid-body techniques for external beam radiotherapy treatment planning for patients treated in the prone position without fiducial markers.

METHODS

17 patients with biopsy-proven rectal carcinoma were scanned with CT and MRI in the prone position without the use of fiducial markers. A reference co-registration was performed by consensus of a radiologist and two physicists. This was compared with two automated and two manual techniques on two separate treatment planning systems. Accuracy and reproducibility were analysed using a measure of target registration error (TRE) that was based on the average distance of the mis-registration between vertices of the clinically relevant gross tumour volume as delineated on the CT image.

RESULTS

An automated technique achieved the greatest accuracy, with a TRE of 2.3 mm. Both automated techniques demonstrated perfect reproducibility and were significantly faster than their manual counterparts. There was a significant difference in TRE between registrations performed on the two planning systems, but there were no significant differences between the manual and automated techniques.

CONCLUSION

For patients with rectal cancer, MRI acquired in the prone treatment position without fiducial markers can be accurately registered with planning CT. An automated registration technique offered a fast and accurate solution with associated uncertainties within acceptable treatment planning limits.

Comparison of virtual and real electric powered wheelchair driving using a position sensing joystick and an isometric joystick

There are limited interface options for electric powered wheelchairs, which results in the inability of some individuals to drive independently. In addition, the development of new interface technologies will necessitate the development of alternative training methods. This study compares a conventional position sensing joystick to a novel isometric joystick during a driving task in a virtual environment and a real environment. The results revealed that there were few differences in task completion time and root-mean-square error (RMSE) between the two types of joysticks. There were significant correlations between the RMSE in the virtual environment and the real environment for both types of joysticks. The data indicate that performance in the virtual environment was representative of driving ability in the real environment, and the isometric joystick performed comparably to the position sensing joystick.

Two ribose-5-phosphate isomerases from Escherichia coli K12: partial characterisation of the enzymes and consideration of their possible physiological roles

Two physically and genetically distinct forms of ribosephosphate isomerase have been identified in Escherichia coli K12. The constitutive ribosephosphate isomerase A has a Km for ribose 5-phosphate (4.4 +/- 0.5 mM) six times greater than that of the inducible ribosephosphate isomerase B (0.83 +/- 0.13 mM). Treatment of the enzymes with 1.25 mM iodoacetate resulted in 100% loss of activity for ribosephosphate isomerase B, whereas ribosephosphate isomerase A was unaffected. Various cellular metabolites were tested and found to be without significant effect on either enzyme. The two enzymes could be separated by filtration on Sephadex G75 superfine and their apparent molecular weights were 45000 for ribosephosphate isomerase A and 32000-34000 for ribosephosphate isomerase B. Under certain conditions the two enzymes showed different patterns of heat inactivation but the results with ribosephosphate isomerase A varied in an unusual way with the protein concentration. Ribosephosphate isomerase B was formed inducibly in a mutant lacking ribosephosphate isomerase A but there was no evidence for the production of ribosephosphate isomerase B in wild-type cells. The formation of ribosephosphate isomerase B was not a consequence of the ribosephosphate isomerase B mutation, since strains could be constructed which formed both enzymes constitutively in the anticipated amounts. The ribosephosphate isomerase formed by a secondary mutant obtained from a ribosephosphate-isomerase-A-negative strain was identified as ribosephosphate isomerase B on the basis of its Km, elution profile from Sephadex G75, inhibition of iodoacetate, and heat inactivation. The ribosephosphate isomerases of another Escherichia coli K12 strain, X289, were investigated, since their properties were reported to be different from many of these described here for ribosephosphate isomerases A and B. In our hands strain X289 contained two ribosephosphate isomerases apparently identical to ribosephosphate isomerases A and B. The evidence to date suggests that ribosephosphate isomerase A catalyses the formation of ribose 5-phosphate from ribulose 5-phosphate and also participates in the reverse reaction during ribose and adenosine catabolism. The normal physiological role of the inducible ribosephosphate isomerase B is still uncertain.

Mechanical efficiency and user power requirement with a pushrim activated power assisted wheelchair

The objective of this study was to quantify the difference in mechanical efficiency and user power generation between traditional manual wheelchairs and a pushrim activated power assisted wheelchair (PAPAW). Ten manual wheelchair users were evaluated in a repeated measures design trial with and without the PAPAW for propulsion efficiency. Subjects propelled a Quickie GP equipped with the PAPAW and their own chair on a computer controlled wheelchair dynamometer at five different resistance levels. Power output, user power with the PAPAW hubs, subjects' oxygen consumption per minute and mechanical efficiency were analyzed. Metabolic energy and user power were significantly lower (p<0.05), and mechanical efficiency significantly higher with the PAPAW than with subjects' own chairs. Subjects needed to generate on average 3.65 times more power when propelling their own wheelchairs as compared to PAPAW. Mean mechanical efficiency over all trials was 80.33% higher with the power assisted hubs. PAPAW provides on average 73% of the total power when subjects propel with power assistance. Significantly increased efficiency and reduced requirement of user power is achieved using the PAPAW. With use, the PAPAW may contribute to delaying secondary injuries of manual wheelchair users. In addition, it may be suitable for people who have (or at risk for) upper extremity joint degeneration, reduced exercise capacity, low strength or endurance who currently use electric powered wheelchairs.

Subcloning and nucleotide sequence of the 3,4-dihydroxyphenylacetate (homoprotocatechuate) 2,3-dioxygenase gene from Escherichia coli C

A cloned gene encoding the Escherichia coli C homoprotocatechuate (HPC) dioxygenase, an aromatic ring cleavage enzyme, was used to produce large amounts of the protein. Preparations of E. coli C HPC dioxygenase, whether expressed from the cloned gene or produced by the bacterium, lost activity very rapidly. The pure protein showed one type of subunit of Mr 33,000. The first 21 N-terminal amino acids were sequenced and the data used to confirm that the open reading frame of 831 bp, identified from the nucleotide sequence, encoded HPC dioxygenase. Comparison of the derived amino acid sequence with those of other extradiol and intradiol dioxygenases showed no obvious similarity to any of them.

Changes in oxygenation during radiotherapy in carcinoma of the cervix

PURPOSE

The aim of this study was to investigate changes in tumor oxygenation, assessed by polarographic needle electrode measurements, following fractionated external beam radiotherapy in carcinoma of the cervix.

METHODS AND MATERIALS

Normal and tumor tissue oxygenation was measured in 19 patients prior to radiotherapy and after 40-45 Gy of external beam radiotherapy delivered in 20 fractions over 4 weeks. All measurements were performed during anesthesia.

RESULTS

There was no significant difference in the level of normal tissue oxygenation pre- and post radiotherapy. The individual patient median tumor pO2 values ranged from 0 to 31 mmHg pre-radiotherapy and 1 to 61 mmHg post-radiotherapy. The mean of the 19 median pO2 values increased from 8 (SD +/- 10) mmHg to 20 (+/- 20) mmHg following external beam radiotherapy. The increase was significant by paired Wilcoxon test (p = 0.011). There was also a significant fall in the proportion of values < 5 mmHg (p = 0.040). Although this value remained constant, or fell, in the majority of patients (15/19), it increased in 4 tumors. Tumor size pre- and postradiotherapy did not correlate with the level of pretreatment oxygenation; neither did the change in tumor size and change in level of oxygenation.

CONCLUSION

The level of tumor oxygenation increased in the majority of patients (15/19) following 40-45 Gy of radiotherapy in carcinoma of the cervix.

Evaluation of selected ultralight manual wheelchairs using ANSI/RESNA standards

OBJECTIVES

To provide data for clinicians and wheelchair users to compare the durability, strength, stability, and cost effectiveness of four different ultralight wheelchair models, and to compare the results of this study with those published for lightweight wheelchairs.

DESIGN

Standards testing and cost-effectiveness analysis of four wheelchair models from different manufacturers (12 wheelchairs total).

RESULTS

There were significant differences (p< or =.05) in the fatigue life and value (equivalent cycles per dollar) among the ultralight wheelchairs tested. There was also a significant difference (p< or =.05) in rearward stability tilt angle for the least and most stable configurations. There were no differences in forward and lateral stability. The ultralight wheelchairs (1,009,108 cycles) had significantly (p< or =.05) higher fatigue lives than previously reported for lightweight wheelchairs (187,370 cycles). The lightweight wheelchairs had a mean value of 210 cycles per dollar compared to 673 cycles per dollar for the ultralight wheelchairs. The difference in value for the lightweight and ultralight wheelchairs was statistically significant (p< or =.05).

CONCLUSION

There were differences in the fatigue life and value among the four models of ultralight manual wheelchairs tested. This indicates that ultralight manual wheelchairs are not all of equal quality. The fatigue life and value of the ultralight manual wheelchairs were significantly higher than those previously reported for lightweight manual wheelchairs. This indicates that ultralight wheelchairs may be of higher quality than lightweight manual wheelchairs. Clinicians and consumers should seriously consider selecting an ultralight manual wheelchair to meet their wheelchair mobility needs.

Demographic and socioeconomic factors associated with disparity in wheelchair customizability among people with traumatic spinal cord injury

OBJECTIVES

To determine if a standard of care for wheelchair provision exists within the participating centers and if there is disparity in wheelchair customizability among the study sample.

DESIGN

Convenience sample survey.

SETTING

Thirteen Model Spinal Cord Injury Systems that provide comprehensive rehabilitation for people with traumatic spinal cord injury (SCI) and that are part of the national database funded through the US Department of Education.

PARTICIPANTS

A total of 412 people with SCI who use wheelchairs over 40 hours a week.

INTERVENTION

Survey information was obtained from subjects via telephone and in-person interviews and from the national database. Collected information included age, race, education, level of injury, and wheelchair funding source.

MAIN OUTCOME MEASURES

Number and type (manual or power) of wheelchairs. Wheelchair customizability as defined by design features (eg, adjustable axle position, programmable controls).

RESULTS

Ninety-seven percent of manual wheelchair users and 54% of power wheelchair users had customizable wheelchairs. No power wheelchair user received a wheelchair without programmable controls. Minorities with low socioeconomic backgrounds (low income, Medicaid/Medicare recipients, less educated) were more likely to have standard manual and standard programmable power wheelchairs. Older subjects were also more likely to have standard programmable power wheelchairs.

CONCLUSIONS

The standard of care for manual wheelchair users with SCI is a lightweight and customizable wheelchair. The standard of care for power wheelchairs users has programmable controls. Unfortunately, socioeconomically disadvantaged people were less likely to receive customizable wheelchairs.

Functional assessment and performance evaluation for assistive robotic manipulators: Literature review

CONTEXT

The user interface development of assistive robotic manipulators can be traced back to the 1960s. Studies include kinematic designs, cost-efficiency, user experience involvements, and performance evaluation. This paper is to review studies conducted with clinical trials using activities of daily living (ADLs) tasks to evaluate performance categorized using the International Classification of Functioning, Disability, and Health (ICF) frameworks, in order to give the scope of current research and provide suggestions for future studies.

METHODS

We conducted a literature search of assistive robotic manipulators from 1970 to 2012 in PubMed, Google Scholar, and University of Pittsburgh Library System - PITTCat.

RESULTS

Twenty relevant studies were identified.

CONCLUSION

Studies were separated into two broad categories: user task preferences and user-interface performance measurements of commercialized and developing assistive robotic manipulators. The outcome measures and ICF codes associated with the performance evaluations are reported. Suggestions for the future studies include (1) standardized ADL tasks for the quantitative and qualitative evaluation of task efficiency and performance to build comparable measures between research groups, (2) studies relevant to the tasks from user priority lists and ICF codes, and (3) appropriate clinical functional assessment tests with consideration of constraints in assistive robotic manipulator user interfaces. In addition, these outcome measures will help physicians and therapists build standardized tools while prescribing and assessing assistive robotic manipulators.

Shoulder and elbow motion during two speeds of wheelchair propulsion: a description using a local coordinate system

Individuals who propel wheelchairs have a high prevalence of upper extremity injuries. To better understand the mechanism behind these injuries this study investigates the motion of the shoulder and elbow during wheelchair propulsion. The objectives of this study are: (1) To describe the motion occurring at the shoulder and elbow in anatomical terms during wheelchair propulsion; (2) to obtain variables that characterize shoulder and elbow motion and are statistically stable; (3) to determine how these variables change with speed. The participants in the study were a convenience sample of Paralympic athletes who use manual wheelchairs for mobility and have unimpaired arm function. Each subject propelled an ultralight wheelchair on a dynamometer at 1.3 and 2.2 meters per second (m/s). Biomechanical data was obtained using a force and moment sensing pushrim and a motion analysis system. The main outcome measures investigated were: maximum and minimum angles while in contact with the pushrim, range of motion during the entire stroke and peak accelerations. All of the measures were found to be stable at both speeds (Cronbach's alpha > 0.8). The following measures were found to differ with speed (data format: measure at 1.3 m/s +/- SD; measure at 2.2 m/s +/- SD): minimum shoulder abduction angle during propulsion (24.5 degrees +/- 6.7, 21.6 degrees +/- 7.2), range of motion during the entire stroke in elbow flexion/extension (54.0 degrees +/- 9.9, 58.1 degrees +/- 10.4) and shoulder sagittal flexion/extension (74.8 degrees +/- 9.4, 82.6 degrees +/- 8.5), and peak acceleration in shoulder sagittal flexion/extension (4044 degrees/s2 +/- 946, 7146 degrees/s2 +/- 1705), abduction/adduction (2678 degrees/s2 +/- 767, 4928 degrees/s2 +/- 1311), and elbow flexion/extension (9355 degrees/s2 +/- 4120, 12889 degrees/s2 +/- 5572). This study described the motion occurring at the shoulder and elbow using a local coordinate system. Stable parameters that characterize the propulsive stroke and differed with speed were found. In the future these same parameters may provide insight into the cause and prevention of shoulder and elbow injuries in manual wheelchair.

Neuromuscular effects of rocuronium bromide (Org 9426) during fentanyl and halothane anaesthesia

The neuromuscular effects of intravenous rocuronium bromide, 0.6 mg.kg-1 or 0.9 mg.kg-1, were studied in four groups of 10 patients during anaesthesia with or without halothane (0.5-0.75% inspired concentration). Neuromuscular block was monitored using mechanomyography and train-of-four stimulation. The mean times to onset of complete neuromuscular block were 58 and 59 s using the 0.6 mg.kg-1 dose in patients anaesthetised with fentanyl and halothane respectively. The times of 34 min and 33 min for 25% recovery of T1 (first response in the train of four), 54 min and 52 min for 90% recovery of T1, 55 min and 60 min for a train of four ratio of 0.7, and 13 and 13 min respectively for the recovery index (25-75% recovery of T1) were not significantly different in these groups. Complete block with the 0.9 mg.kg-1 dose occurred in 47 s and 44 s respectively in the fentanyl and halothane groups. T1 recovered to 25% in 51 min and 58 min, and to 90% in 77 min and 86 min respectively in the two groups. The recovery indices and the times to spontaneous recovery of the train of four ratio to 0.7 were 17 min and 19 min, and 83 min and 93 min respectively. All the parameters were significantly different between the 0.6 mg.kg-1 and 0.9 mg.kg-1 doses. Halothane in the concentrations used did not influence the neuromuscular effects. It is concluded that rocuronium is a rapidly acting non-depolarising muscle relaxant with a duration of action similar to that of vecuronium and may be a useful alternative to suxamethonium for rapid tracheal intubation.

Biomechanics and strength of manual wheelchair users

BACKGROUND/OBJECTIVE

Previous investigations have identified muscular imbalance in the shoulder as a source of pain and injury in manual wheelchair users. Our aim was to determine whether a correlation exists between strength and pushrim biomechanical variables including: tangential (motive) force (Ft), radial force (Fr), axial force (Fz), total (resultant) force (FR), fraction of effective force (FEF), and cadence.

METHODS

Peak isokinetic shoulder strength (flexion [FLX], extension [EXT], abduction [ABD], adduction [ADD], internal rotation [IR], and external rotation [ER]) was tested in 22 manual wheelchair users with a BioDex system for 5 repetitions at 60 degrees/s. Subjects then propelled their own manual wheelchair at 2 speeds, 0.9 m/s (2 mph) and 1.8 m/s (4 mph), for 20 seconds, during which kinematic (OPTOTRAK) and kinetic (SMARTWHEEL) data were collected. Peak isokinetic forces in the cardinal planes were correlated with pushrim biomechanical variables.

RESULTS

All peak torque strength variables correlated significantly (P < or = 0.05) with Ft, Fr, and FR, but were not significantly correlated with Fz, FEF, or cadence. Finally, there were no relationships found between muscle strength ratios (for example, FLX/EXT) and Ft, Fr, FR, Fz, or FEF.

CONCLUSION

There was a correlation between strength and force imparted to the pushrim among wheelchair users; however, there was no correlation found in wheelchair propulsion or muscle imbalance. Clinicians should be aware of this, and approach strength training and training in wheelchair propulsion techniques separately.

Effective treatment of anal cancer in the elderly with low-dose chemoradiotherapy

Chemoradiotherapy (CRT) is accepted as the standard initial treatment for squamous cell anal cancer. However, frail elderly patients cannot always tolerate full-dose CRT. This paper reports the results of a modified regimen for this group of patients. In all, 16 patients with biopsy-proven squamous cell carcinoma of the anal canal or margin and performance status or co-morbidity precluding the use of full-dose CRT were included in this protocol. The median age was 81 (range 77-91). Patients received a dose of 30 Gy to the gross tumour volume plus 3 cm margin in all directions. Concurrent chemotherapy comprised 5-fluorouracil 600 mg m(-2) given over 24 h on days 1-4 of radiotherapy. The treatment was well tolerated. All 16 patients completed treatment as planned. Only one patient experienced any grade 3 toxicity (skin). The local control at a median follow-up of 16 months was 73% (13 out of 16). The overall survival was 69% and disease-specific survival 86%. This is a well-tolerated regimen for elderly/poor performance patients with anal cancer, which can achieve high rates of local control and survival. Longer follow-up will determine whether these encouraging results are maintained.

Trends and issues in wheelchair technologies

There is an overwhelming need for wheelchairs and the research and development required to make them safer, more effective, and widely available. The following areas are of particular importance: practitioner credentials, accreditation, device evaluation, device user training, patient education, clinical prescribing criteria, national contracts, and access to new technology. There are over 170 U.S. wheelchair manufacturers with a total reported income of $1.33 billion. However, of these companies, only five had sales in excess of $100 million. Wheelchairs account for about 1% of Medicare spending. Use of assistive technology is an increasingly common way of adapting to a disability. The emergence of advanced mobility devices shows promise for the contribution of engineering to the amelioration of mobility impairments for millions of people who have disabilities or who are elderly. Some of the trends in wheelchairs are going to require new service delivery mechanisms, changes to public policy, and certainly greater coordination between consumers, policy makers, manufacturers, researchers, and service providers.

Estimation of the potency of ORG 9426 using two different modes of nerve stimulation

The potency of ORG 9426, a new nondepolarising muscle relaxant, has been estimated using two different modes of nerve stimulation in patients anaesthetised with thiopentone, nitrous oxide-oxygen and intravenous fentanyl. The force of contraction of adductor pollicis was measured following a single twitch (ST) at 0.1 Hz or a train-of-four (TOF) mode of stimulation at 2 Hz every ten seconds. Dose-response curves were constructed using a single-dose method. The ED50, ED90 and ED95 were 147,272 and 305 micrograms.kg-1 respectively using the ST mode and 125,230 and 257 micrograms.kg-1 using the TOF mode of stimulation. The ED50S were not significantly different but the differences between ED90S and ED95S were significant (P less than 0.05) indicating greater sensitivity of the neuromuscular junction using TOF stimulation. The results of this study suggest that the information obtained by single-twitch stimulation is not the same as that obtained from the first response of the TOF stimulation, suggesting apparently increased sensitivity (and apparently greater potency) with the TOF mode of stimulation. Org 9426 appears to be a drug with relatively low potency.

The GAME(Cycle) exercise system: comparison with standard ergometry

BACKGROUND

It is well established that physical activity is beneficial to health. For the individual in a wheelchair, a regular exercise program might not be available or may be too difficult to participate in physically and/or psychologically. Many exercise devices and regimes are boring. The goal, therefore, is to develop a device that makes exercise more exciting and, thus, motivates a person to exercise more or for a longer period of time, yielding increased energy expenditure. Our laboratory developed an interface between an arm ergometer and a computer game that allows the user to control game play on the screen as if using a joystick. The purpose of this study was to determine (a) whether the GAME(Cycle) system would elicit an exercise effect similar to arm ergometry, (b) whether perceived exertion would be different between the 2 devices, and (c) individuals' impressions regarding the GAME(Cycle) system.

METHODS

Thirteen individuals who used wheelchairs participated in the study. Participants were asked to exercise for 2 separate, 19-minute sessions. For 1 session, a GAME(Cycle) system was used and for the other session, the same arm ergometer was used, but without the computer game being played. Physiologic data and perceived exertion were collected for each session.

RESULTS

There were significant differences between playing the game and not playing the game for VO2 (P = 0.03) and VCO2 (P = 0.02), with higher values being found when the game was played. Perceived exertion was not significantly different between the 2 trials.

CONCLUSION

GAME(Cycle) appears to be similar in nature with respect to energy expenditure to arm ergometry. Because this study was conducted on athletes, further research is needed with sedentary individuals to determine exercise effects and perceived exertion.

Rehabilitation medicine summit: building research capacity executive summary

The general objective of the "Rehabilitation Medicine Summit: Building Research Capacity" was to advance and promote research in medical rehabilitation by making recommendations to expand research capacity. The five elements of research capacity that guided the discussions were: 1) researchers; 2) research culture, environment, and infrastructure; 3) funding; 4) partnerships; and 5) metrics. The 100 participants included representatives of professional organizations, consumer groups, academic departments, researchers, governmental funding agencies, and the private sector. The small group discussions and plenary sessions generated an array of problems, possible solutions, and recommended actions. A post-Summit, multi-organizational initiative is called to pursue the agendas outlined in this report (see Additional File 1).

Prostatic mucinous carcinoma

Four criteria are proposed for establishing the pathologic diagnosis of prostatic mucinous carcinoma. Twenty-one reported cases of this rare tumor are reviewed, and a new case is presented. The clinical and pathologic features of 16 authentic features of 16 authentic cases are analyzed.