Characteristics and predicted outcome of patients lost to follow-up after degenerative lumbar spine surgery.

PURPOSE: The relatively large number of participants lost to follow-up (attrition) in spinal registers calls for studies that investigate the features of these individuals and their possible outcome. The aim was to explore the effect of attrition on patient-reported outcome in patients undergoing degenerative lumbar spine surgery. Three groups were studied: spinal stenosis (LSS), disc herniation (LDH) and degenerative disc disorder (DDD). METHODS: Patients who underwent surgery for degenerative lumbar spine conditions during 2008-2012 according to registration in the Swespine national register were eligible for the study. Non-respondents were registered in Swespine prior to surgery, but not at follow-up. Swespine data were merged with hospital data from seven Swedish regions (65% of the population), Statistics Sweden, the National Patient Register and the Social Insurance Agency. Baseline characteristics of non-respondents were described and compared to those of the respondents. Coefficients from regression analyses on PROM values for respondents were used to estimate the levels of PROM values for non-respondents, assuming the same effects of baseline characteristics for the two subgroups. Regression analyses were then conducted to identify variables associated with non-response. The results from the regression analyses were used to predict outcomes for patients with the characteristics of a non-respondent. Primary outcome variable in LSS and LDH was Global Assessment for leg pain, and in DDD, Global Assessment for back pain. RESULTS: Age, sex, educational level, smoking, living alone, being born outside the EU, previous spine surgery and unexpected events before follow-up were factors that were significantly associated with non-response. Being born inside, the EU was important in all of the studied groups (LSS: OR 0.61 p = < 0.000; LDH: OR 0.68 p = 0.001; DDD: OR 0.58 p = 0.04). For spinal stenosis patients, an unexpected event appeared particularly important (OR 3.40, p = 0.000). The predicted outcome of non-respondents was significantly worse than for respondents (LSS: 75.4% successful outcome vs. 78.7%; LDH: 53.9% vs. 58.2%; DDD: 62.7% vs. 67.5%. P-value in all groups = < 0.000). CONCLUSION: Attrition in Swespine cannot be ignored, as non-respondents were predicted to have worse outcome. The effect of attrition bias should always be considered when contemplating outcome recorded in a quality register with patients lost to follow-up.

Remotely sensed thermal decay rate: an index for vegetation monitoring.

Vegetation buffers local diurnal land surface temperatures, however, this effect has found limited applications for remote vegetation characterization. In this work, we parameterize diurnal temperature variations as the thermal decay rate derived by using satellite daytime and nighttime land surface temperatures and modeled using Newton's law of cooling. The relationship between the thermal decay rate and vegetation depends on many factors including vegetation type, size, water content, location, and local conditions. The theoretical relationships are elucidated, and empirical relationships are presented. Results show that the decay rate summarizes both vegetation structure and function and exhibits a high correlation with other established vegetation-related observations. As proof of concept, we interpret 15-year spatially explicit trends in the annual thermal decay rates over Africa and discuss results. Given recent increases in availability of finer spatial resolution satellite thermal measurements, the thermal decay rate may be a useful index for monitoring vegetation.

ISSLS prize in clinical science 2020: the reliability and interpretability of score change in lumbar spine research.

PURPOSE: A statistically significant score change of a PROM (Patient-Reported Outcome Measure) can be questioned if it does not exceed the clinically Minimal Important Change (MIC) or the SDC (Smallest Detectable Change) of the particular measure. The aim of the study was to define the SDC of three common PROMs in degenerative lumbar spine surgery: Numeric Rating Scale (NRSBACK/LEG), Oswestry Disability Index (ODI) and Euroqol-5-Dimensions (EQ-5DINDEX) and to compare them to their MICs. The transition questions Global Assessment (GABACK/LEG) were also explored. METHODS: Reliability analyses were performed on a test-retest population of 182 symptomatically stable patients, with similar characteristics as the Swespine registry population, who underwent surgery for degenerative lumbar spine conditions 2017-2018. The MIC values were based on the entire registry (n = 98,732) using the ROC curve method. The ICC for absolute agreement was calculated in a two-way random-effects single measures model. For categorical variables, weighted kappa and exact agreement were computed. RESULTS: For the NRS, the SDC exceeded the MIC (NRSBACK:3.6 and 2.7; NRSLEG: 3.7 and 3.2, respectively), while they were of an equal size of 18 for the ODI. The gap between the two estimates was remarkable in the EQ-5DINDEX, where SDC was 0.49 and MIC was 0.10. The GABACK/LEG showed an excellent agreement between the test and the retest occasion. CONCLUSION: For the tested PROM scores, the changes must be considerable in order to distinguish a true change from random error in degenerative lumbar spine surgery research. These slides can be retrieved under Electronic Supplementary Material.

Follow-up of degenerative lumbar spine surgery-PROMs stabilize after 1 year: an equivalence study based on Swespine data.

PURPOSE: To evaluate the outcome of degenerative lumbar spine surgery in a credible way, patient-reported outcome measures (PROMs) should be assessed after an adequate follow-up period. Most authors/journals consider a follow-up period of less than two years to be too short. The purpose of this study was to explore the possibility of restricting follow-up to one year. METHODS: Adult patients operated between 1998 and 2017 were retrieved from Swespine (Lumbar Disc Herniation n = 31,314, Lumbar Spinal Stenosis n = 53,043 and Degenerative Disc Disease n = 14,375). The proportion reaching the minimal important change (MIC) in Visual Analogue Scale for pain (VASBACK/LEG), Oswestry Disability Index (ODI) and the quality-of-life measure EQ-5DINDEX at 1 and 2 years, respectively, was calculated. The single-item questions such as Global Assessment (GABACK/LEG) and Satisfaction were analysed by the McNemar test. Threshold values for a successful outcome based on the final scores of each PROM at 1 and 2 years post-surgery were also defined. RESULTS: For all the three diagnostic groups, the differences in proportions reaching MIC of each PROM at 1 and 2 years were below 2%. Global Assessment and Satisfaction with outcome at one year remained at 2 years. There were no important differences of threshold values of treatment success based on final scores CONCLUSION: No clinically important changes in PROMs appeared between 1 and 2 years after surgery for degenerative lumbar conditions, demonstrating that a follow-up period of 1 year as opposed to 2 years is sufficient in effectiveness studies if PROMs are to be used as outcome variables. These slides can be retrieved under Electronic Supplementary Material.

Interpretation of HbA1c in primary care and potential influence of anaemia and chronic kidney disease: an analysis from the Copenhagen Primary Care Laboratory (CopLab) Database.

AIMS: To investigate, in a large population in primary care, the relationship between fasting plasma glucose and HbA1c measurements, as well as the clinical implications of anaemia or chronic kidney disease for the interpretation of HbA1c values. METHODS: From a primary care resource, we examined HbA1c and fasting plasma glucose as well as haemoglobin and estimated GFR. We stratified observations by chronic kidney disease stage and anaemia level. The estimation of the mean fasting plasma glucose level from HbA1c alone, and from HbA1c , haemoglobin and estimated GFR, respectively, was evaluated. RESULTS: In 198 346 individuals, the fasting plasma glucose-HbA1c relationship mimicked the regression described in the A1c-Derived Average Glucose (ADAG) study, which was based on average capillary and interstitial glucose. The fasting plasma glucose-HbA1c relationship was unaffected in mild to moderate chronic kidney disease and in mild to moderate anaemia. The correlation changed only in severe hyperglycaemia and concurrent severe anaemia or when estimated GFR was <45 ml/min/1.73m², so that glucose concentration was underestimated by HbA1c in anaemia and overestimated in chronic kidney disease. The prevalence of estimated GFR <30 ml/min/1.73m² was 0.82%, while the prevalence of haemoglobin <81 g/l (5.0 mmol/l) was 0.11%. CONCLUSIONS: The relationship between fasting plasma glucose and HbA1c mimics that of the people with diabetes included in the ADAG study. Mild to moderate anaemia and CKD do not have a significant impact on the interpretation of HbA1c as a marker of retrograde glycaemia. Hence, it seems justified to use HbA1c without adjustment in primary care.

The value of patient global assessment in lumbar spine surgery: an evaluation based on more than 90,000 patients.

PURPOSE: There are two, principally different ways to obtain patient opinions regarding the outcome of spine surgery: using prospective multi-item questionnaires preoperatively and at follow-up, and using a retrospective single-item question at follow-up-both methods have distinct advantages and limitations. The purpose of the study was to explore the utility of using the simple transition question global assessment, GA, ("How is your back/leg pain today as compared to before the surgery?") as an overall patient-reported outcome measure (PROM) based on the large real-life database in the Swedish spine registry (Swespine). METHODS: The correlation between GA and the score-changes and the final scores at 1 year of follow-up for the PROMs VAS, ODI, and EQ-5D was examined. The correlations between GA and item-specific domains within the ODI, EQ-5D and SF-36 as well as the discriminative ability of PROMs with GA as reference criterion were also analysed. The cohort consisted of 94,132 patients registered in Swespine who were surgically treated for disc herniation, spinal stenosis or degenerative disc disease. RESULTS: The correlation coefficients for GA vs. the score-changes were lower than for GA vs final scores. For VAS they ranged for the different diagnosis groups from 0.33 to 0.61 and from 0.50 to 0.79, respectively. For ODI, the corresponding values ranged from 0.43 to 0.65 and 0.63 to 0.76; for the EQ-5D from 0.32 to 0.45 and 0.54 to 0.71. Further, GA showed a somewhat stronger correlation to pain-specific PROMs than to quality-of-life PROMs. CONCLUSIONS: The single-item outcome measure global assessment (GA) appears to be a feasible overall patient-reported outcome measure (PROM) and a useful reference for interpreting the scores of patient-reported outcome measures.

Psychosocial therapy and causes of death after deliberate self-harm: a register-based, nationwide multicentre study using propensity score matching.

BACKGROUND: Psychosocial therapy after deliberate self-harm might be associated with reduced risk of specific causes of death. METHOD: In this matched cohort study, we included patients, who after an episode of deliberate self-harm received psychosocial therapy at a Suicide Prevention Clinic in Denmark between 1992 and 2010. We used propensity score matching in a 1:3 ratio to select a comparison group from 59 046 individuals who received standard care. National Danish registers supplied data on specific causes of death over a 20-year follow-up period. RESULTS: At the end of follow-up, 391 (6.9%) of 5678 patients in the psychosocial therapy group had died, compared with 1736 (10.2%) of 17 034 patients in the matched comparison group. Lower odds ratios of dying by mental or behavioural disorders [0.54, 95% confidence interval (CI) 0.37-0.79], alcohol-related causes (0.63, 95% CI 0.50-0.80) and other diseases and medical conditions (0.61, 95% CI 0.49-0.77) were noted in the psychosocial therapy group. Also, we found a reduced risk of dying by suicide as well as other external causes, however, not by neoplasms and circulatory system diseases. Numbers needed to treat were 212.9 (95% CI 139.5-448.4) for mental or behavioural disorders as a cause of death, 111.1 (95% CI 79.2-210.5) for alcohol-related causes and 96.8 (95% CI 69.1-161.8) for other diseases and medical conditions. CONCLUSIONS: Our findings indicate that psychosocial therapy after deliberate self-harm might reduce long-term risk of death from select medical conditions and external causes. These promising results should be tested in a randomized design.

Publication rate of paper and podium presentations from the European Section of the Cervical Spine Research Society Annual Meeting.

PURPOSE: The Cervical Spine Research Society Europe (CSRS-E) actively promotes scientific activities, the annual meeting being the most evident of them. The publication rate of oral and poster presentations at the annual meeting could be a measure for the success of the promotional activities. The publication rates of abstracts presented at the annual European meetings of the CSRS are unknown. The quality of the abstracts presented at a conference is reflected by the publication rate. A high publication rate is usually interpreted as representative of high scientific value of the conference. METHODS: Poster and podium presentations from the 2007 to 2012 annual meetings were identified. Pubmed was used to search for the abstract title and/or the combination of authors to verify whether the data were published in a peer-reviewed journal. Abstracts were considered published if the data presented at the meeting were identical to that in the publication. The journals in which the data were published were identified, as well as the origin of the research centre. RESULTS: From 2007 to 2012 826 abstracts were featured at the CSRS Europe annual meetings. There were 236 podium presentations and 590 poster presentations. 42 % of the podium presentations resulted in a publication, and 28 % of the poster presentations led to a publication. Overall, 32 % of accepted abstracts effectuated a publication in a peer-reviewed scientific journal. Abstracts from European research groups had a publication rate of 29 % compared to 34 % for abstracts from non-European research groups. Spine, European Spine Journal, Journal of Spinal Disorders and Techniques and J Neurosurgery Spine were the most common publication journals for the abstracts. The mean impact factor of the journals in which was published was 2.2. CONCLUSION: 42 % of the abstracts that were accepted for podium presentation at the CSRS Europe resulted in a publication in peer-reviewed MEDLINE indexed journals. Publication rates are at the high end of the publication rate spectrum of abstracts accepted for European scientific meetings.

Prevalence and clinical significance of neutropenia discovered in routine complete blood cell counts: a longitudinal study.

BACKGROUND: Neutropenia, defined as an absolute blood neutrophil count (ANC) <1.5 G L(-1) , may accompany a variety of diseases. However, the clinical significance of neutropenia detected in a routine complete blood cell count is poorly understood. METHODS: Using a primary care resource, comprising more than 370 000 individuals, we assessed the association with a number of previously recognized conditions as well as all-cause mortality in the 4 years following the identification of neutropenia. By matching laboratory data with Danish nationwide health registers, risk estimates were assessed. RESULTS: Neutropenia was observed in approximately 1% of all individuals and was associated dose dependently with viral infections, haematological malignancies (but not autoimmune disorders or solid cancers) and mortality. Neutropenia was particularly associated with HIV, acute leukaemias and myelodysplastic syndromes. Odds ratios [95% confidence interval (CI)] for viral infections were 2.32 (1.84-2.91), 2.80 (2.20-3.57) and 4.77 (3.22-7.07) for subnormal (≥1.5-1.8 G L(-1) ), mild (≥1.0-1.5 G L(-1) ) and moderate-severe (≥0.0-1.0 G L(-1) ) neutropenic individuals, respectively (all P < 0.001). Likewise, odds ratios (95% CI) for haematological malignancies were 3.23 (2.35-4.45), 8.69 (6.58-11.47) and 46.03 (33.98-62.35 ), for the same neutropenia levels, respectively (all P < 0.001). Thus, the lower the ANC, the greater the likelihood of these diseases. The relative risk estimates observed for severe neutropenia corresponded to absolute risks of haematological malignancies and mortality from any cause of 40% and >50%, respectively. CONCLUSIONS: Neutropenia is an ominous sign necessitating careful follow-up. The risk estimates presented here support focusing attention to viral diseases and haematological malignancies when neutropenia is observed.

Efficiency of different selection strategies against boar taint in pigs.

The breeding scheme of a Swiss sire line was modeled to compare different target traits and information sources for selection against boar taint. The impact of selection against boar taint on production traits was assessed for different economic weights of boar taint compounds. Genetic gain and breeding costs were evaluated using ZPlan+, a software based on selection index theory, gene flow method and economic modeling. Scenario I reflected the currently practiced breeding strategy as a reference scenario without selection against boar taint. Scenario II incorporated selection against the chemical compounds of boar taint, androstenone (AND), skatole (SKA) and indole (IND) with economic weights of -2.74, -1.69 and -0.99 Euro per unit of the log transformed trait, respectively. As information sources, biopsy-based performance testing of live boars (BPT) was compared with genomic selection (GS) and a combination of both. Scenario III included selection against the subjectively assessed human nose score (HNS) of boar taint. Information sources were either station testing of full and half sibs of the selection candidate or GS against HNS of boar taint compounds. In scenario I, annual genetic gain of log-transformed AND (SKA; IND) was 0.06 (0.09; 0.02) Euro, which was because of favorable genetic correlations with lean meat percentage and meat surface. In scenario II, genetic gain increased to 0.28 (0.20; 0.09) Euro per year when conducting BPT. Compared with BPT, genetic gain was smaller with GS. A combination of BPT and GS only marginally increased annual genetic gain, whereas variable costs per selection candidate augmented from 230 Euro (BPT) to 330 Euro (GS) or 380 Euro (both). The potential of GS was found to be higher when selecting against HNS, which has a low heritability. Annual genetic gain from GS was higher than from station testing of 4 full sibs and 76 half sibs with one or two measurements. The most effective strategy to reduce HNS was selecting against chemical compounds by conducting BPT. Because of heritabilities higher than 0.45 for AND, SKA and IND and high genetic correlations to HNS, the (correlated) response in units of the trait could be increased by 62% compared with scenario III with GS and even by 79% compared with scenario III, with station testing of siblings with two measurements. Increasing the economic weights of boar taint compounds amplified negative effects on average daily gain, drip loss and intramuscular fat percentage.

Improving the therapeutic ratio in stereotactic radiosurgery: optimizing treatment protocols based on kinetics of repair of sublethal radiation damage.

Sublethal damage after radiation exposure may become lethal or be repaired according to repair kinetics. This is a well-established concept in conventional radiotherapy. It also plays an important role in single-dose stereotactic radiotherapy treatments, often called stereotactic radiosurgery, when duration of treatment is extended due to source decay or treatment planning protocol. The purpose of this study is to look into the radiobiological characteristics of normal brain tissue and treatment protocols and find a way to optimize the time course of these protocols. The general problem is nonlinear and can be solved numerically. For numerical optimization of the time course of radiation protocol, a biexponential repair model with slow and fast components was considered. With the clinically imposed constraints of a fixed total dose and total treatment time, three parameters for each fraction (dose-rate, fraction duration, time of each fraction) were simultaneously optimized. A biological optimization can be performed by maximizing the therapeutic difference between tumor control probability and normal tissue complication probability. Specifically, for gamma knife radiosurgery, this approach can be implemented for normal brain tissue or tumor voxels separately in a treatment plan. Differences in repair kinetics of normal tissue and tumors can be used to find clinically optimized protocols. Thus, in addition to considering the physical dose in tumor and normal tissue, we also account for repair of sublethal damage in both these tissues.

Radiobiological evaluation of breast cancer radiotherapy accounting for the effects of patient positioning and breathing in dose delivery. A meta analysis.

In breast cancer radiotherapy, significant discrepancies in dose delivery can contribute to underdosage of the tumor or overdosage of normal tissue, which is potentially related to a reduction of local tumor control and an increase of side effects. To study the impact of these factors in breast cancer radiotherapy, a meta analysis of the clinical data reported by Mavroidis et al. (2002) in Acta Oncol (41:471-85), showing the patient setup and breathing uncertainties characterizing three different irradiation techniques, were employed. The uncertainties in dose delivery are simulated based on fifteen breast cancer patients (5 mastectomized, 5 resected with negative node involvement (R-) and 5 resected with positive node involvement (R1)), who were treated by three different irradiation techniques, respectively. The positioning and breathing effects were taken into consideration in the determination of the real dose distributions delivered to the CTV and lung in each patient. The combined frequency distributions of the positioning and breathing distributions were obtained by convolution. For each patient the effectiveness of the dose distribution applied is calculated by the Poisson and relative seriality models and a set of parameters that describe the dose-response relations of the target and lung. The three representative radiation techniques are compared based on radiobiological measures by using the complication-free tumor control probability, P(+) and the biologically effective uniform dose, (BEUD)concepts. For the Mastectomy case, the average P(+) values of the planned and delivered dose distributions are 93.8% for a (BEUD)(CTV) of 51.8 Gy and 85.0% for a (BEUD)(CTV) of 50.3 Gy, respectively. The respective total control probabilities, P(B) values are 94.8% and 92.5%, whereas the corresponding total complication probabilities, P(1) values are 0.9% and 7.4%. For the R- case, the average P(+) values are 89.4% for a (BEUD)(CTV) of 48.9 Gy and 88.6% for a (BEUD)(CTV) of 49.2 Gy and 85.5% for a (BEUD)(CTV) of 49.1 Gy, respectively. The respective PB values are 90.2% and 90.1%, whereas the corresponding P(+) values are 4.1% and 4.6%. The combined effects of positioning uncertainties and breathing can introduce a significant deviation between the planned and delivered dose distributions in lung in breast cancer radiotherapy. The positioning and breathing uncertainties do not affect much the dose distribution to the CTV. The simulated delivered dose distributions show larger lung complication probabilities than the treatment plans. This means that in clinical practice the true expected complications are underestimated. Radiation pneumonitis of Grade 1-2 is more frequent and any radiotherapy optimization should use this as a more clinically relevant endpoint.

A comparative analysis of radiobiological models for cell surviving fractions at high doses.

For many years the linear-quadratic (LQ) model has been widely used to describe the effects of total dose and dose per fraction at low-to-intermediate doses in conventional fractionated radiotherapy. Recent advances in stereotactic radiosurgery (SRS) and stereotactic radiotherapy (SRT) have increased the interest in finding a reliable cell survival model, which will be accurate at high doses, as well. Different models have been proposed for improving descriptions of high dose survival responses, such as the Universal Survival Curve (USC), the Kavanagh-Newman (KN) and several generalizations of the LQ model, e.g. the Linear-Quadratic-Linear (LQL) model and the Pade Linear Quadratic (PLQ) model. The purpose of the present study is to compare a number of models in order to find the best option(s) which could successfully be used as a fractionation correction method in SRT. In this work, six independent experimental data sets were used: CHOAA8 (Chinese hamster fibroblast), H460 (non-small cell lung cancer, NSLC), NCI-H841 (small cell lung cancer, SCLC), CP3 and DU145 (human prostate carcinoma cell lines) and U1690 (SCLC). By detailed comparisons with these measurements, the performance of nine different radiobiological models was examined for the entire dose range, including high doses beyond the shoulder of the survival curves. Using the computed and measured cell surviving fractions, comparison of the goodness-of-fit for all the models was performed by means of the reduced χ (2)-test with a 95% confidence interval. The obtained results indicate that models with dose-independent final slopes and extrapolation numbers generally represent better choices for SRT. This is especially important at high doses where the final slope and extrapolation numbers are presently found to play a major role. The PLQ, USC and LQL models have the least number of shortcomings at all doses. The extrapolation numbers and final slopes of these models do not depend on dose. Their asymptotes for the cell surviving fractions are exponentials at low as well as high doses, and this is in agreement with the behaviour of the corresponding experimental data. This is an important improvement over the LQ model which predicts a Gaussian at high doses. Overall and for the highlighted reasons, it was concluded that the PLQ, USC and LQL models are theoretically well-founded. They could prove useful compared to the other proposed radiobiological models in clinical applications for obtaining uniformly accurate cell surviving fractions encountered in stereotactic high-dose radiotherapy as well as at medium and low doses.

A reverse J-shaped association of all-cause mortality with serum 25-hydroxyvitamin D in general practice: the CopD study.

CONTEXT: Optimal levels of vitamin D have been a topic of heavy debate, and the correlation between 25-hydroxyvitamin D [25(OH)D] levels and mortality still remains to be established. OBJECTIVE: The aim of the study was to determine the association between all-cause mortality and serum levels of 25(OH)D, calcium, and PTH. DESIGN AND SETTING: We conducted a retrospective, observational cohort study, the CopD Study, in a single laboratory center in Copenhagen, Denmark. PARTICIPANTS: Serum 25(OH)D was analyzed from 247,574 subjects from the Copenhagen general practice sector. In addition, serum levels of calcium, albumin-adjusted calcium, PTH, and creatinine were measured in 111,536; 20,512; 34,996; and 189,496 of the subjects, respectively. MAIN OUTCOME MEASURES: Multivariate Cox regression analysis was used to compute hazard ratios for all-cause mortality. RESULTS: During follow-up (median, 3.07 yr), 15,198 (6.1%) subjects died. A reverse J-shaped association between serum level of 25(OH)D and mortality was observed. A serum 25(OH)D level of 50-60 nmol/liter was associated with the lowest mortality risk. Compared to 50 nmol/liter, the hazard ratios (95% confidence intervals) of all-cause mortality at very low (10 nmol/liter) and high (140 nmol/liter) serum levels of 25(OH)D were 2.13 (2.02-2.24) and 1.42 (1.31-1.53), respectively. Similarly, both high and low levels of albumin-adjusted serum calcium and serum PTH were associated with an increased mortality, and secondary hyperparathyroidism was associated with higher mortality (P < 0.0001). CONCLUSION: In this study from the general practice sector, a reverse J-shaped relation between the serum level of 25(OH)D and all-cause mortality was observed, indicating not only a lower limit but also an upper limit. The lowest mortality risk was at 50-60 nmol/liter. The study did not allow inference of causality, and further studies are needed to elucidate a possible causal relationship between 25(OH)D levels, especially higher levels, and mortality.

Temporal frequency requirements for tissue velocity imaging of the fetal heart.

OBJECTIVES: The high velocity and short duration of myocardial motion requires a high sampling rate to obtain adequate temporal resolution; this issue becomes even more important when taking into consideration the high fetal heart rate. In this study we have established optimal sampling requirements for assessing the duration of various cardiac cycle events and myocardial velocities of the fetal heart using color-coded tissue velocity imaging (TVI). METHODS: Recordings from 30 fetuses were acquired at an initial frame rate of 180-273 frames/s. All TVI recordings were performed from an apical four-chamber view and stored as cineloops of five to 10 consecutive cardiac cycles for subsequent offline analysis using software enabling a reduction in frame rate. Different components of the myocardial velocity curve, obtained from the basal part of the ventricular septum, were measured at the initial frame rate and compared with their equivalents at gradually decreased frame rates. RESULTS: As acquisition frame rate was reduced, there was a marked increase in deviation from the initial values, resulting in an underestimation of all systolic and diastolic velocities. For the measured durations, there was a clear tendency to underestimate isovolumetric contraction and relaxation, and a clear tendency to overestimate ventricular ejection and diastolic E-wave and A-wave. An acceptable ⩽ 5% deviation from the value obtained at the highest frame rate corresponded to measurements obtained at above 150-200 frames/s. CONCLUSIONS: A high sampling rate of at least 200 frames/s is necessary for adequate reconstruction of TVI data for the fetal heart. Frame rates that are too low result in considerable loss of temporal and velocity information.

Tracking of airborne radionuclides from the damaged Fukushima Dai-ichi nuclear reactors by European networks.

Radioactive emissions into the atmosphere from the damaged reactors of the Fukushima Dai-ichi nuclear power plant (NPP) started on March 12th, 2011. Among the various radionuclides released, iodine-131 ((131)I) and cesium isotopes ((137)Cs and (134)Cs) were transported across the Pacific toward the North American continent and reached Europe despite dispersion and washout along the route of the contaminated air masses. In Europe, the first signs of the releases were detected 7 days later while the first peak of activity level was observed between March 28th and March 30th. Time variations over a 20-day period and spatial variations across more than 150 sampling locations in Europe made it possible to characterize the contaminated air masses. After the Chernobyl accident, only a few measurements of the gaseous (131)I fraction were conducted compared to the number of measurements for the particulate fraction. Several studies had already pointed out the importance of the gaseous (131)I and the large underestimation of the total (131)I airborne activity level, and subsequent calculations of inhalation dose, if neglected. The measurements made across Europe following the releases from the Fukushima NPP reactors have provided a significant amount of new data on the ratio of the gaseous (131)I fraction to total (131)I, both on a spatial scale and its temporal variation. It can be pointed out that during the Fukushima event, the (134)Cs to (137)Cs ratio proved to be different from that observed after the Chernobyl accident. The data set provided in this paper is the most comprehensive survey of the main relevant airborne radionuclides from the Fukushima reactors, measured across Europe. A rough estimate of the total (131)I inventory that has passed over Europe during this period was <1% of the released amount. According to the measurements, airborne activity levels remain of no concern for public health in Europe.

Investigating the clinical aspects of using CT vs. CT-MRI images during organ delineation and treatment planning in prostate cancer radiotherapy.

In order to apply highly conformal dose distributions, which are characterized by steep dose fall-offs, it is necessary to know the exact target location and extension. This study aims at evaluating the impact of using combined CT-MRI images in organ delineation compared to using CT images alone, on the clinical results. For 10 prostate cancer patients, the respective CT and MRI images at treatment position were acquired. The CTV was delineated using the CT and MRI images, separately, whereas bladder and rectum were delineated using the CT images alone. Based on the CT and MRI images, two CTVs were produced for each patient. The mutual information algorithm was used in the fusion of the two image sets. In this way, the structures drawn on the MRI images were transferred to the CT images in order to produce the treatment plans. For each set of structures of each patient, IMRT and 3D-CRT treatment plans were produced. The individual treatment plans were compared using the biologically effective uniform dose () and the complication-free tumor control probability (P(+)) concepts together with the DVHs of the targets and organs at risk and common dosimetric criteria. For the IMRT treatment, at the optimum dose level of the average CT and CT-MRI delineated CTV dose distributions, the P(+) values are 74.7% in both cases for a of 91.5 Gy and 92.1 Gy, respectively. The respective average total control probabilities, PB are 90.0% and 90.2%, whereas the corresponding average total complication probabilities, P(I) are 15.3% and 15.4%. Similarly, for the 3D-CRT treatment, the average P(+) values are 42.5% and 46.7%, respectively for a of 86.4 Gy and 86.7 Gy, respectively. The respective average P(B) values are 80.0% and 80.6%, whereas the corresponding average P(I) values are 37.4% and 33.8%, respectively. For both radiation modalities, the improvement mainly stems from the better sparing of rectum. According to these results, the expected clinical effectiveness of IMRT can be increased by a maximum ΔP(+) of around 0.9%, whereas of 3D-CRT by about 4.2% when combined CT-MRI delineation is performed instead of using CT images alone. It is apparent that in both IMRT and 3D-CRT radiation modalities, the better knowledge of the CTV extension improved the produced dose distribution. It is shown that the CTV is irradiated more effectively, while the complication probabilities of bladder and rectum, which is the principal organs at risk, are lower in the CT-MRI based treatment plans.

Comparison of the helical tomotherapy against the multileaf collimator-based intensity-modulated radiotherapy and 3D conformal radiation modalities in lung cancer radiotherapy.

OBJECTIVES: The aim of this study was to compare three-dimensional (3D) conformal radiotherapy and the two different forms of IMRT in lung cancer radiotherapy. METHODS: Cases of four lung cancer patients were investigated by developing a 3D conformal treatment plan, a linac MLC-based step-and-shoot IMRT plan and an HT plan for each case. With the use of the complication-free tumour control probability (P(+)) index and the uniform dose concept as the common prescription point of the plans, the different treatment plans were compared based on radiobiological measures. RESULTS: The applied plan evaluation method shows the MLC-based IMRT and the HT treatment plans are almost equivalent over the clinically useful dose prescription range; however, the 3D conformal plan inferior. At the optimal dose levels, the 3D conformal treatment plans give an average P(+) of 48.1% for a effective uniform dose to the internal target volume (ITV) of 62.4 Gy, whereas the corresponding MLC-based IMRT treatment plans are more effective by an average ΔP(+) of 27.0% for a Δ effective uniform dose of 16.3 Gy. Similarly, the HT treatment plans are more effective than the 3D-conformal plans by an average ΔP(+) of 23.8% for a Δ effective uniform dose of 11.6 Gy. CONCLUSION: A radiobiological treatment plan evaluation can provide a closer association of the delivered treatment with the clinical outcome by taking into account the dose-response relations of the irradiated tumours and normal tissues. The use of P - effective uniform dose diagrams can complement the traditional tools of evaluation to compare and effectively evaluate different treatment plans.

Analytical description of the LET dependence of cell survival using the repairable-conditionally repairable damage model.

In light-ion radiation therapy, both the dose and the local energy spectrum, which is often characterized with the linear energy transfer (LET), must be considered. In treatment optimization, it is advantageous to use a radiobiological model that analytically accounts for both dose and LET for the ion type of interest. With such a model the biological effect can also be estimated for dose and LET combinations for which there are no observations in the underlying experimental data. In this study, the repairable-conditionally repairable (RCR) damage model was extended by expressing its parameters as functions of LET to provide a radiobiological model that accounts for both the dose and the LET for a given ion type and cell line. This LET-parameterized RCR model was fitted to published cell survival data for HSG and V79 cells irradiated with carbon ions and for T1 cells irradiated with helium ions. To test the robustness of the model, fittings to only a subset of the data were performed. Good agreement with the cell survival data was obtained, including survival data for LET values not used for model fitting, opening up the possibility of using the model in treatment planning for light ions.

Clinical factors of importance for outcome after lumbar disc herniation surgery: long-term follow-up.

Factors as age, sex, smoking, duration of leg pain, working status, type/level of disc herniation and psychosocial factors have been demonstrated to be of importance for short-term results after lumbar discectomy. There are few studies with long-term follow-up. In this prospective study of lumbar disc herniation patients undergoing surgery, the result was evaluated at 2 and 5-10 (mean 7.3) years after surgery. Predictive factors for satisfaction with treatment and objective outcome were investigated. Out of the included 171 patients undergoing lumbar discectomy, 154 (90%) patients completed the 2-year follow-up and 140 (81%) completed the long-term follow-up. Baseline data and questionnaires about leg- and back pain intensity (VAS), duration of leg pain, disability (Oswestry Disability Index), depression (Zung Depression Scale), sick leave and employment status were obtained preoperatively, at 2-year- and long-term follow-up. Primary outcome included patient satisfaction with treatment (at both time points) and assessment of an independent observer at the 2-year follow-up. Secondary outcomes at 2-year follow-up were improvement of leg and back pain, working capacity and the need for analgesics or sleeping pills. In about 70% of the patients excellent or good overall result was reported at both follow-ups, with subjective outcome measurements. The objective evaluation after 2 years was in agreement with this result. Time on sick leave was found to be a clinically important predictor of the primary outcomes, with a potential of changing the probability of a satisfactory outcome (both objective and subjective) from around 50% (sick leave >3 months) to 80% (sick leave <2 months). Time on sick leave was also an important predictor for several of the secondary outcomes; e.g. working capacity and the need for analgesics.