Thermal and non-thermal effects of capacitive-resistive electric transfer application on different structures of the knee: a cadaveric study.

Capacitive-resistive electric transfer therapy is used in physical rehabilitation and sports medicine to treat muscle, bone, ligament and tendon injuries. The purpose is to analyze the temperature change and transmission of electric current in superficial and deep knee tissues when applying different protocols of capacitive-resistive electric transfer therapy. Five fresh frozen cadavers (10 legs) were included in this study. Four interventions (high/low power) were performed for 5 min by a physiotherapist with experience. Dynamic movements were performed to the posterior region of the knee. Capsular, intra-articular and superficial temperature were recorded at 1-min intervals and 5 min after the treatment, using thermocouples placed with ultrasound guidance. The low-power protocols had only slight capsular and intra-capsular thermal effects, but electric current flow was observed. The high-power protocols achieved a greater increase in capsular and intra-articular temperature and a greater current flow than the low-power protocols. The information obtained in this in vitro study could serve as basic science data to hypothesize capsular and intra-articular knee recovery in living subjects. The current flow without increasing the temperature in inflammatory processes and increasing the temperature of the tissues in chronic processes with capacitive-resistive electric transfer therapy could be useful for real patients.

Monopolar dielectric diathermy by emission of radiofrequency in Patellofemoral pain. A single-blind-randomized clinical trial.

Despite the high incidence of patellofemoral pain syndrome (PFPS), few studies show the effects of radiofrequency on pain and functionality in these patients. For this reason, the aim of this study was to determine the efficacy of monopolar dielectric diathermy by emission of radiofrequency (MDR) in dynamic applications aimed at treating pain and improving function in patients with PFPS. For this purpose, a single-blind randomized clinical trial was conducted. Eighty-four participants with PFPS were evenly divided into an experimental group (EG) and a control group (CG). All subjects receive 10 min of daily home exercises along 3 weeks, and in addition, the subjects of the EG received 10 sessions based on the dynamic application of MDR. Variables measured included Visual Analogue Scale (VAS), DN4 questionnaire, Lower Extremity Functionality Scale (LEFS), Kujala scale, Range of Movement (ROM) in knee flexion and extension and drug intake. The EG showed a statistically significant reduction in pain (VAS = 4.8 [5.5-4.1] [p < .001]; DN4 = 3.8 [4.4-3.2] [p < .001]), and an increase in functionality (LEFS = 16 [19-13] [p < .001]; Kujala = 19 [23-14] [p < .001]) and in ROM (flexion 18º [21º-16º] [p < .001]). No statistically significant changes in drug intake were found. Based on this data, the dynamic application of MDR seems effective in reducing pain and increasing functionality and flexion in patients with PFPS. Diathermy by emission of radiofrequency could be recommended as complement or main therapy in the treatment of PFPS.

COMPARISON OF RADIATION EXPOSURE TO THE PATIENT AND CONTRAST DETAIL RESOLUTIONS ACROSS LOW DOSE 2D/3D SLOT SCANNER AND TWO CONVENTIONAL DIGITAL RADIOGRAPHY X-RAY IMAGING SYSTEMS.

PURPOSE: To assess and compare the radiation dose and image quality of the low dose 2D/3D EOS slot scanner (LDSS) to conventional digital radiography (DR) X-ray imaging systems for chest and knee examination protocols. METHODS AND MATERIALS: The effective doses (ED) to the patient in the chest and knee clinical examination protocols for LDSS and DR X-ray imaging systems were determined using the dose area product and PCXMC Monte Carlo simulation software. The CDRAD phantom was imaged with 19 cm, and 13 cm thick Polymethyl Methacrylate (PMMA) blocks to simulate the chest and knees respectively of a patient of average adult size. The contrast detail resolution was calculated using image analysis software. RESULTS: The EDs for the LDSS default setting were up to 69% and 51% lower than for the DR systems for the chest (speed 4) and knee (speed 6) protocols, respectively, while for the increased dose level setting then the EDs were up to 42% and 35% lower than for the DR systems for the chest (speed 6) and knee (speed 8) protocols respectively. At the default setting, the contrast detail was lowest for the default setting of the 2D/3D low dose slot scanner (LDSS) for both chest and knee examinations, but at the highest dose levels then the threshold were equal or higher than the contrast resolution of DR imaging systems. CONCLUSION: The LDSS has the potential to be used for clinical diagnosis of chest and knee examinations using the higher dose level. For speed 6 in chest protocol and speed 8 in knee protocol, the measured contrast detail resolution was comparable with the DR systems but at a lower effective dose.

Acute effects of photobiomodulation therapy (PBMT) combining laser diodes, light-emitting diodes, and magnetic field in exercise capacity assessed by 6MST in patients with COPD: a crossover, randomized, and triple-blinded clinical trial.

Chronic obstructive pulmonary disease (COPD) is characterized by dyspnea, as well as musculoskeletal and systemic manifestations. Photobiomodulation therapy (PBMT) with use of low-level laser therapy (LLLT) and/or light-emitting diode therapy (LEDT) is an electrophysical intervention that has been found to minimize or delay muscle fatigue. The aim of this study was to evaluate the acute effect of PBMT with combined use of lasers diodes, light-emitting diodes (LEDs), magnetic field on muscle performance, exercise tolerance, and metabolic variables during the 6-minute stepper test (6MST) in patients with COPD. Twenty-one patients with COPD (FEV1 46.3% predicted) completed the 6MST protocol over 2 weeks, with one session per week. PBMT/magnetic field or placebo (PL) was performed before each 6MST (17 sites on each lower limb, with a dose of 30 J per site, using a cluster of 12 diodes 4 × 905 nm super-pulsed laser diodes, 4 × 875 nm infrared LEDs, and 4 × 640 nm red LEDs; Multi Radiance Medical™, Solon, OH, USA). Patients were randomized into two groups before the test according to the treatment they would receive. Assessments were performed before the start of each protocol. The primary outcomes were oxygen uptake and number of steps, and the secondary outcome was perceived exertion (dyspnea and fatigue in the lower limbs). PBMT/magnetic field applied before 6MST significantly increased the number of steps during the cardiopulmonary exercise test when compared to the results with placebo (129.8 ± 10.6 vs 116.1 ± 11.5, p = 0.000). PBMT/magnetic field treatment also led to a lower score for the perception of breathlessness (3.0 [1.0-7.0] vs 4.0 [2.0-8.0], p = 0.000) and lower limb fatigue (2.0 [0.0-5.0] vs 4.0 [0.0-7.0], p = 0.001) compared to that with placebo treatment. This study showed that the combined application of PBMT and magnetic field increased the number of steps during the 6MST and decreased the sensation of dyspnea and lower limb fatigue in patients with COPD.

Integrating a low-field open MR scanner with a static proton research beam line: proof of concept.

On-line image guidance using magnetic resonance (MR) imaging is expected to improve the targeting accuracy of proton therapy. However, to date no combined system exists. In this study, for the first time a low-field open MR scanner was integrated with a static proton research beam line to test the feasibility of simultaneous irradiation and imaging. The field-of-view of the MR scanner was aligned with the beam by taking into account the Lorentz force induced beam deflection. Various imaging sequences for extremities were performed on a healthy volunteer and on a patient with a soft-tissue sarcoma of the upper arm, both with the proton beam line switched off. T 1-weighted spin echo images of a tissue-mimicking phantom were acquired without beam, with energised beam line magnets and during proton irradiation. Beam profiles were acquired for the MR scanner's static magnetic field alone and in combination with the dynamic gradient fields during the acquisition of different imaging sequences. It was shown that MR imaging is feasible in the electromagnetically contaminated environment of a proton therapy facility. The observed quality of the anatomical MR images was rated to be sufficient for target volume definition and positioning. The tissue-mimicking phantom showed no visible beam-induced image degradation. The beam profiles depicted no influence due to the dynamic gradient fields of the imaging sequences. This study proves that simultaneous irradiation and in-beam MR imaging is technically feasible with a low-field MR scanner integrated with a static proton research beam line.

Long-Term Effect of Pulsed Nd:YAG Laser in the Treatment of Children with Juvenile Rheumatoid Arthritis: A Randomized Controlled Trial.

OBJECTIVE: The aim of this study was to evaluate the long-term impact of a pulsed neodymium-doped yttrium aluminum garnet (Nd:YAG) laser [high-intensity laser therapy (HILT)] in the treatment of juvenile rheumatoid arthritis (JRA). MATERIALS AND METHODS: A sample of 30 children participated in this study (15 in the laser group and 15 in the placebo group), with a mean age of 10.53 ± 1.25 years. Children who were randomly assigned to the laser group received HILT thrice per week for 4 weeks, plus the exercise program. HILT scanned each knee with 600 J in two phases and 15 J to 10 points for a total of 750 J for each knee. The placebo laser group received placebo HILT plus the same exercise program. The outcomes measured in this study were the pain level by the visual analog scale (VAS) and gait parameters by the GAITRite® system. Statistical analysis was performed by ANOVA with repeated measures to compare the differences between the baseline, post-treatment, and 12-week follow-up measurements for both groups. The level of significance was set at p < 0.05. RESULTS: The VAS results significantly decreased post-treatment in the laser group relative to the placebo group and were still improved at the 12-week follow-up. Gait parameters significantly increased in the laser group after 4 weeks of treatment and after 12 weeks compared to the placebo group. CONCLUSIONS: HILT, when combined with an exercise program, appears to be more effective in children with JRA than a placebo laser procedure with exercises.

COMPARING LUNGS, LIVER AND KNEE MEASUREMENT GEOMETRIES AT VARIOUS TIMES POST INHALATION OF 239Pu AND 241Am.

In-vivo measurement of Pu/241Am in workers is carried out by placing suitable detector above lungs, liver and skeleton, as major fraction of Pu/Am is transferred to liver and skeleton, after its retention in entry organ. In this work, committed effective dose (CED) corresponding to minimum detectable activity for Type M and Type S 239Pu/241Am deposited in these organs are presented and a monitoring protocol of organ measurement giving lowest CED at different time intervals post inhalation is described. We have observed, for Type M compounds, lung measurement is most sensitive method during initial days after exposure. Liver measurement yields lowest CED between 100 and 5000 d and beyond that bone measurement gives lowest CED. For Type S compounds lung measurement remains most sensitive method even up to 10 000 d post inhalation. This study will be useful for the assessment of CED due to internally deposited 239Pu/241Am in the workers.

Sesamoid bone of the medial collateral ligament of the knee joint

The variable occurrence of the sesamoid bones supports the theory stating that the development and evolution of these bones are controlled through the interaction between intrinsic genetic factors and extrinsic stimuli. In the present article we report a sesamoid bone at the medial collateral ligament of the knee joint, a newly discovered finding in human and veterinary medicine

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Changes of articular cartilage and subchondral bone after extracorporeal shockwave therapy in osteoarthritis of the knee.

We assessed the pathological changes of articular cartilage and subchondral bone on different locations of the knee after extracorporeal shockwave therapy (ESWT) in early osteoarthritis (OA). Rat knees under OA model by anterior cruciate ligament transaction (ACLT) and medial meniscectomy (MM) to induce OA changes. Among ESWT groups, ESWT were applied to medial (M) femur (F) and tibia (T) condyles was better than medial tibia condyle, medial femur condyle as well as medial and lateral (L) tibia condyles in gross osteoarthritic areas (p<0.05), osteophyte formation and subchondral sclerotic bone (p<0.05). Using sectional cartilage area, modified Mankin scoring system as well as thickness of calcified and un-calcified cartilage analysis, the results showed that articular cartilage damage was ameliorated and T+F(M) group had the most protection as compared with other locations (p<0.05). Detectable cartilage surface damage and proteoglycan loss were measured and T+F(M) group showed the smallest lesion score among other groups (p<0.05). Micro-CT revealed significantly improved in subchondral bone repair in all ESWT groups compared to OA group (p<0.05). There were no significantly differences in bone remodeling after ESWT groups except F(M) group. In the immunohistochemical analysis, T+F(M) group significant reduced TUNEL activity, promoted cartilage proliferation by observation of PCNA marker and reduced vascular invasion through observation of CD31 marker for angiogenesis compared to OA group (P<0.001). Overall the data suggested that the order of the effective site of ESWT was T+F(M) ≧ T(M) > T(M+L) > F(M) in OA rat knees.

A MONTE CARLO STUDY OF SIMULATED MEASUREMENTS OF RADIONUCLIDES IN BONE.

When measuring the internally deposited activity in the bone of a subject, the placement of the detector is critical. This study reports the simulated counting efficiencies for three counting geometries, the skull, knee and shin, using 13 different voxel phantoms. It shows that the range of counting efficiencies for a given geometry is large for the studied phantoms, especially at low energies. Skull counting offers higher efficiency for low energies such as the 17 keV compared to knee counting or shin counting, but this advantage disappears when the energy is higher such as at 185 keV. This work also shows that the calibration phantom may greatly impact the accuracy of the activity estimate in bone counting, with uncertainties increasing greatly as the photon energy is reduced. Estimating the activity of a radionuclide in bone from direct counting has large uncertainties, and the dose calculated from a skeleton measurement would need careful analysis and, if possible, supporting data from other bioassay measurements.

Is there a role of pulsed electromagnetic fields in management of patellofemoral pain syndrome? Randomized controlled study at one year follow-up.

Patellofemoral pain syndrome (PFPS) is a common cause of recurrent or chronic knee pain in young adults, generally located in the retropatellar region. Etiology is controversial and includes several factors, such as anatomical defects, muscular imbalance, or joint overuse. Good results have been reported with exercise therapy, including home exercise program (HEP). Joint inflammation with increase of pro-inflammatory cytokines levels in the synovial fluid might be seen especially when chondromalacia becomes evident. Biophysical stimulation with pulsed electromagnetic fields (PEMFs) has shown anti-inflammatory effects and anabolic chondrocyte activity. The purpose of this randomized controlled study was to evaluate if the combination of HEP with PEMFs was more effective than HEP alone in PFPS treatment. Thirty-one PFPS patients were enrolled in this study. All patients were instructed to train with HEP. Patients in the PEMFs group associated HEP with PEMFs. Function and pain were assessed with Victorian Institute of Sport Assessment score (VISA), Visual Analog Scale (VAS), and Feller's Patella Score at baseline at 2, 6, and 12 months of follow-up. Drug assumption was also recorded. Increase in VISA score was significantly higher in PEMFs group compared to controls at 6 and 12 months, as well as the increase in the Feller's Patella Score at 12 months. VAS score became significantly lower in the PEMFs group with respect to control group since 6 month follow-up. Pain reduction obtained with PEMFs enhanced practicing therapeutic exercises leading to a better recovery process; this is extremely important in addressing the expectations of young patients, who wish to return to sporting activities.

Feasibility of MV CBCT-based treatment planning for urgent radiation therapy: dosimetric accuracy of MV CBCT-based dose calculations.

Unlike scheduled radiotherapy treatments, treatment planning time and resources are limited for emergency treatments. Consequently, plans are often simple 2D image-based treatments that lag behind technical capabilities available for nonurgent radiotherapy. We have developed a novel integrated urgent workflow that uses onboard MV CBCT imaging for patient simulation to improve planning accuracy and reduce the total time for urgent treatments. This study evaluates both MV CBCT dose planning accuracy and novel urgent workflow feasibility for a variety of anatomic sites. We sought to limit local mean dose differences to less than 5% compared to conventional CT simulation. To improve dose calculation accuracy, we created separate Hounsfield unit-to-density calibration curves for regular and extended field-of-view (FOV) MV CBCTs. We evaluated dose calculation accuracy on phantoms and four clinical anatomical sites (brain, thorax/spine, pelvis, and extremities). Plans were created for each case and dose was calculated on both the CT and MV CBCT. All steps (simulation, planning, setup verification, QA, and dose delivery) were performed in one 30 min session using phantoms. The monitor units (MU) for each plan were compared and dose distribution agreement was evaluated using mean dose difference over the entire volume and gamma index on the central 2D axial plane. All whole-brain dose distributions gave gamma passing rates higher than 95% for 2%/2 mm criteria, and pelvic sites ranged between 90% and 98% for 3%/3 mm criteria. However, thoracic spine treatments produced gamma passing rates as low as 47% for 3%/3 mm criteria. Our novel MV CBCT-based dose planning and delivery approach was feasible and time-efficient for the majority of cases. Limited MV CBCT FOV precluded workflow use for pelvic sites of larger patients and resulted in image clearance issues when tumor position was far off midline. The agreement of calculated MU on CT and MV CBCT was acceptable for all treatment sites.

Monte Carlo simulation of in vivo measurement of the most suitable knee position for the optimal measurement of activity.

A new computational model has been developed using the Monte Carlo (MC) technique to simulate in vivo measurements with the objective of understanding the most precise measurement location with respect to quantifying the activity of Am in the bones. To benchmark the model, in vivo measurements were performed on the U.S. Transuranium and Uranium Registries (USTUR) case 0846 leg. Front and lateral measurements of the knee of the USTUR case 0846 leg in a bent position and the same measurements with the leg in a straight position using a HP(Ge) detector were completed. Experimental results concluded that the front measurement of the knee in a bent leg position gave the highest count rate, which is an indication of optimal detection efficiency. Therefore, this geometry and knee-detector position were considered as the most appropriate position for knee monitoring. A computational model using MCNPX version 2.6.0 was used to simulate the experimental measurements by using a leg voxel phantom. The mean value and standard deviation (SD) of peak efficiency due to an isotropic 59.5-keV photon from Am were calculated in four different counting geometries. An extra sum of squares F-test was performed on the mean values of the simulated detection efficiencies. The p-value obtained from this statistical test indicates that the differences among the mean values for different counting geometries were significant. These results suggest that the front measurement of a knee in a bent leg position is the optimal counting geometry for in vivo measurement of Am deposited in the bones. The computational model was validated through comparison of the measured and simulated detection efficiencies. It was observed that there is no difference at the 0.1 significant levels between the simulated and measured detection efficiencies in assessment of Am within the bones.

Evaluation of (241)Am deposited in different parts of the leg bones and skeleton to justify in vivo measurements of the knee for estimating total skeletal activity.

The percentage of Am deposited in different parts of leg bones relative to the total leg activity was calculated from radiochemical analysis results from six whole body donors participating in the U.S. Transuranium and Uranium Registries (USTUR). In five of these six USTUR cases, the percentage of Am deposited in the knee region as well as in the entire leg was separately calculated relative to total skeletal activity. The purpose of this study is to find a region in the leg that is both suitable for in vivo measurement of Am deposited in the bones and has a good correlation with the total skeletal Am burden. In all analyzed cases, the femur was the bone with the highest percentage of Am deposited in the leg (48.8%). In the five cases that have complete whole skeletal analysis, the percentage of Am activity in the knee relative to entire skeletal activity was 4.8%, and the average value of its coefficient of variation was 10.6%. The percentage of Am in the leg relative to total skeletal activity was 20% with an average coefficient of variation of 13.63%. The Am activity in the knee as well as in the leg was strongly correlated (R = 99.5% and R = 99.1%, respectively) with the amount of Am activity in the entire skeleton using a simple linear relationship. The highest correlation was found between the amount of Am deposited in the knee and the amount of Am deposited in the entire skeleton. This correlation is important because it might enable an accurate assessment of the total skeletal Am burden to be performed from in vivo monitoring of the knee region. In all analyzed cases, an excellent correlation (R = 99.9%) was found between the amount of Am activity in the knee and the amount of Am activity in the entire leg. The results of this study suggest three simple models: two models to predict the total skeletal activity based on either leg or knee activity, and the third model to predict the total leg activity based on knee activity. The results also suggest that the knee region is a suitable position for in vivo measurements of Am deposited in the bones and also for an accurate and efficient detection system. Detector efficiency should be apparently calibrated based on only the Am burden in the knee region bones instead of Am activity deposited in the entire leg.

Radiosynoviorthesis of knees by means of 166Ho-holmium-boro-macroaggregates.

The aim of this study was to evaluate adverse and therapeutic effects of applicated holmium-boro-macroaggregates (HBMAs) in the radiosynoviorthesis (RSO) of knees in patients suffering from chronic synovitis. We started RSO of the knees by means of a new radiopharmaceutical (RF) HBMA in patients with gonarthrosis, rheumatoid arthritis, chronic synovitis, psoriatic arthritis, and gout arthropathy. Seventeen (17) intra-articular injections were performed in 15 patients who were receiving a mean activity of 972 MBq (range, 904-1057) of 166Ho-HBMA. Patient inclusion to the study followed a series of inclusion and exclusion criterions. The patients were hospitalized for 3 days. Side-effects were evaluated during their hospital stay and again after 6-8 weeks. Static scintigraphy of knee joints and measurements of blood radioactivity were performed. Therapeutic effects were evaluated after 6-8 weeks and at 6 months. In 2 hours and 2 days following the application, we proved, by means of knee and inguinal scintigraphy, only insignificant radiopharmaceutical leakage from the joint cavity to the inguinal lymph nodes in 4 patients. In the treated patients, no serious adverse effects occurred. Nine (9) patients were without complaints, 4 patients had slight knee exudation, and 2 patients had great exudation. Therapeutic effects were as follows: 2 patients were without pain, 9 were with lower pain, 3 were with the same pain, and 1 patient was with increased pain. Joint motion was improved in 7 patients, remained the same in 7 patients, and was impaired in 1 patient. Analgesics consumption was lower in 5 patients, the same in 9 patients, and greater in 1 patient. Knee exudation was absent in 2 patients, lower in 4 patients, the same in 6 patients, and greater in 3 patients. In 3 patients it was necessary to do surgical RSO. This RF can extend the range of clinically used radiopharmaceuticals for RSO and to supplement space between 90Y with high energy and 186Re with 169Er with lower beta energy. The energy of 166Ho is suitable for great and medium joints (i.e., knees, hips, shoulders, elbows, wrists, and ankles).

The amplitude of force variability is correlated in the knee extensor and elbow flexor muscles.

The purpose of this study was to determine motor output variability for different muscles in the same individuals. Ten young (21.7 +/- 3.4 years) and ten elderly (72.1 +/- 3.9 years) men underwent assessment of maximal isometric (MVC) and dynamic (1-RM) strength, and performed constant-force (2-50% MVC), constant-load (5-50% 1-RM load), and unloaded postural contractions as steadily as possible with the first dorsal interosseus (FDI), elbow flexors (EF), and knee extensors (KE). The coefficient of variation (CV) of force for isometric contractions and the standard deviation (SD) of acceleration for concentric, eccentric, and postural contractions were calculated. The 1-RM load, the CV of force for four of five isometric target forces, and the SD of acceleration during postural contractions were correlated between the EF and KE muscles. MVC force, 1-RM load, and SD of acceleration during postural contractions were not correlated between the FDI/EF or FDI/KE. The CV of force was correlated between the FDI/EF and FDI/KE for two of five isometric target forces. The SD of acceleration during concentric and eccentric contractions was not correlated between muscles. The normalized fluctuations during isometric contractions were greater for the FDI compared with the EF and KE. Elderly adults displayed greater fluctuations only for the FDI during low-force isometric and postural contractions. The dominant frequency of fluctuations was similar for the EF and KE muscles. The correlated fluctuations for the EF and KE muscles, within subjects, suggests that the two motor neuron pools transform the various neural inputs similarly.

Distribution of radiation in synovectomy of the knee with 166Ho-FHMA using image fusion.

BACKGROUND: Radiation synovectomy is an effective technique for the treatment of chronic synovitis in patients with rheumatoid arthritis (RA), and is an alternative for surgical synovectomy. Holmium ferric hydroxide macroaggregates (166Ho-FHMA) is suitable for radiation synovectomy, especially because it emits high-energy beta particles and a smaller proportion of low-energy photons that are suitable for gamma-camera imaging. OBJECTIVE: The aim of this study was to develop a method to fuse 166Ho-FHMA single photon emission computed tomography (SPECT) and magnetic resonance (MRI) images, to show the distribution of 166Ho-FHMA inside the joint with images that localize synovitis. METHODS: The knees of 6 patients with RA were treated with 166Ho-FHMA. (99m)Tc-human immunoglobulin ((99m)Tc-HIG) SPECT images and MRI images were taken before 166Ho-FHMA injections. 166Ho-FHMA SPECT images were taken 4, 28, and 40 hours after injections. SPECT and MRI images were merged using a specific image fusion method, called mutual information algorithm, to study associations between anatomical and metabolic information from these images. RESULTS: Fusion of SPECT and MRI images indicated that intensity of radioactivity was associated with the amount of synovitis. Activity distribution of 166Ho-FHMA could be registered using anatometabolic images. CONCLUSIONS: A new method to fuse the distribution of radiation in the synovectomy of the knee was developed using SPECT/MRI image registration. Image registration of SPECT and MRI can be used to determine the activity distribution of radioisotopes in relation to synovitis.

Enhancement of REM sleep during extraocular light exposure in humans.

This study examined the effects on sleep of light administered to an extraocular site. A 3-h photic stimulus was applied to the popliteal region during sleep in 14 human subjects. Each subject also underwent a control stimulus condition during a separate laboratory session. The proportion of rapid eye movement (REM) sleep during the 3-h light administration session increased by an average of 31% relative to the control condition. The frequency but not the duration of REM episodes was altered during light exposure, thereby shortening the REM/non-REM (NREM) cycle length. No other sleep stages were significantly affected during light administration nor was sleep architecture altered after the light-exposure interval. These results confirm that extraocular light is transduced into a signal that is received and processed by the human central nervous system. In addition, they expand to a novel sensory modality previous findings that REM sleep can be enhanced by sensory stimulation.

Radiation dose and image information in computed radiography. A phantom study of angle measurements in the weight-bearing knee.

PURPOSE: To establish a correlation between radiation dose and diagnostic accuracy when employing a new digital method for angle determinations. The specific intention was to determine how far the radiation dose can be reduced without losing measuring accuracy and to compare this radiation dose with that employed with our conventional method. MATERIAL AND METHODS: An image succession of an anthropomorphic phantom was generated with a computed radiography (CR) system, by reducing the exposure stepwise. The images were archived and transferred to a workstation for evaluation. The intraobserver variation of two angle determinations was used as an indicator of the evaluation accuracy. Patient radiation doses were measured with thermoluminescent dosimeters. The energy imparted, indicating the relative risk associated with exposure to ionising radiation, and the effective dose, which determines the absolute risk, were calculated. RESULTS AND CONCLUSION: No significant correlation was found between patient dose and measuring accuracy within the evaluated exposure interval. At the lowest exposure of the CR system, the energy imparted to the patient was 30 microJ. Compared with our conventional analogue method this is a reduction by 98%. The effective dose was as low as 1.5 microSv. The CR technique creates possibilities to adapt exposure parameters, and thus the radiation dose to the patient, according to the purpose of the investigation.