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PubMed2004

Reproducibility of atopy patch tests with Dermatophagoides: a study on 85 patients with atopic dermatitis.

Atopy patch tests (APTs) are considered a useful addition to standard testing procedures for the identification of allergens triggering the appearance of eczema in patients with atopic dermatitis (AD). The aim of the study was to evaluate the reproducibility of APTs with house dust mites by simultaneously patch testing AD patients. 85 subjects affected by AD, 36 males and 48 females, aged from 1 to 52 years, were patch tested with Dermatophagoides mix (D. pteron/D. farinae) 20% pet. In our patients, the percentage of agreement between the frequency of positive and negative responses to Dermatophagoides mix was 96.7%. Reproducibility was highly satisfactory, as evaluated by k-value (0.953). As regards the agreement in the intensity of APT responses to Dermatophagoides mix between the right and left sides, we found that reproducibility was also highly satisfactory (k = 0.851). In conclusion, for Dermatophagoides APTs, the agreement rate was similar to that of standard patch tests, and therefore APTs may be considered sufficiently reproducible to be employed as a diagnostic testing procedure.

Adolescent↗

PubMed2003

Tumor response to chemotherapy: the validity and reproducibility of RECIST guidelines in NSCLC patients.

We investigated the validity and inter-criteria reproducibility between RECIST (Response Evaluation Criteria in Solid Tumors) guidelines and WHO (World Health Organization) criteria, considering the decrease in patient numbers resulting from inclusion of the minimum lesion size criterion introduced in RECIST guidelines. RECIST guidelines are based on unidimensional measurement and exclusion of small lesions from measurement. The aims of the study were to examine: (1) the effect of the minimum lesion size criterion, (2) the validity of unidimensional and bidimensional measurements, i.e., their relationship with tumor volume, (3) the inter-criteria reproducibility between current RECIST guidelines and previous WHO criteria. One hundred and twenty patients with non-small cell lung cancer (NSCLC) in clinical trials were evaluated. By applying the minimum lesion size criterion, six cases became ineligible without any influence on precision of tumor volume measurement. In the validity study, actual tumor volume was regarded as the gold standard. Although the unidimensional measurement had a lower correlation with tumor volume value than the bidimensional measurement, both the unidimensional measurement and bidimensional measurement correlated sufficiently well with tumor volume changes and the assessed tumor volume response. In the inter-criteria reproducibility study between RECIST guidelines and WHO criteria, the response rate assessed by RECIST guidelines (19.3%) was almost the same as that assessed by WHO criteria (20.0%). In conclusion, RECIST guidelines are adequate for evaluating tumor response to chemotherapy in terms of both validity in relation to tumor volume and inter-criteria reproducibility with the WHO criteria.

Adult↗

PubMed1994

Reproducibility of non-invasive measurement and of short-term variability of blood pressure and heart rate in healthy volunteers.

1. Spectral analyses of blood pressure and heart rate oscillations are increasingly used to assess the influences of diseases and drugs on the autonomic nervous system. Such influences can only be interpreted in view of the spontaneous variability of these oscillations. We therefore studied the reproducibility of power spectral analyses of blood pressure and heart rate fluctuations measured by a non-invasive finger plethysmographic method in 24 healthy volunteers. 2. Intra-observer reproducibility was assessed from measurements obtained on 3 consecutive days and 1 month later in each subject. Inter-observer reproducibility was assessed by comparing measurements made by two observers on one occasion. 3. There was no significant difference in standard haemodynamic and spectral analysis parameters (low frequency: 60-130 mHz and high frequency: respiration rate +/- 30 mHz) measured on 3 consecutive days and 1 month later in each subject. The standard deviation of differences between systolic blood pressure or heart rate oscillations on different occasions was in the 150-200 and 50-100 mm Hg Hz-1/2 or beats min-1 Hz-1/2 range for low frequency and high frequency oscillations respectively. Similar results were found when inter-observer reproducibility was considered. 4. From these results, we derived a sample-size table giving the number of subjects to be included in studies of cross-over or parallel design in order to detect a non-random difference in spectral analysis parameters.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1995

Reproducibility of a histogenetic classification of thymic epithelial tumours.

A histogenetic classification of thymic epithelial neoplasms proposed by Müller-Hermelink and co-workers has been shown by a number of recent studies to be of clinical and prognostic value. Reproducibility is an important criterion for the acceptance of any new classification for general diagnostic use. The reproducibility of this classification was tested on 51 cases of thymic epithelial neoplasia, by comparing results obtained by pathologists working from published criteria only with those results obtained by the pathologists who developed the classification. In 78% of cases there was complete concordance of results. Analysis of the 22% discordant cases showed that this discordance was due to a degree of subjectivity in determining cut-off points between categories adjacent to each other in the morphological spectrum of thymic epithelial neoplasia (medullary v. mixed, cortical v. well-differentiated thymic carcinoma). In terms of the important clinical distinction between benign (medullary and mixed) thymomas and those with more aggressive biological behaviour (cortical types and well-differentiated thymic carcinoma), the degree of reproducibility was 96%. The high degree of reproducibility of this histogenetic classification of thymic epithelial neoplasms should facilitate its acceptance and use in routine diagnostic pathology.

Adolescent↗

PubMed1998

Validity and reproducibility of a self-administered food frequency questionnaire in older people.

This study assesses the validity and reproducibility of a 145-item self-administered food frequency questionnaire (FFQ) in a representative older population aged 63 to 80. Semi-quantitative FFQs were completed by 89% of 3,654 residents attending a community-based eye study in Sydney, Australia. The FFQ's validity was assessed against three, four-day weighed food records (WFRs) completed four months apart by 79 people. A further 152 subjects completed a repeat FFQ about a year after the baseline FFQ, of whom 131 completed a second repeat FFQ about six weeks later. Both short and long-term reproducibility of the FFQ were assessed using data from these subjects. Comparison of the FFQ with the average of the three, four-day weighed food records resulted in energy-adjusted Spearman correlations above 0.5 for most of the nutrients. The proportion of subjects correctly classified to within one quintile category for each nutrient intake ranged from 57% for zinc to 82% for vitamin C. with most nutrients correctly classified within one quintile for about 70% of subjects. Quadratic weighted kappas were reasonable, between 0.3 and 0.5 for most nutrients. The FFQ was highly reproducible in the short term, with correlations for most nutrients about 0.70 to 0.80 and acceptably reproducible in the longer term, with correlations mostly 0.60 to 0.70. The results verify that it is possible to use relatively simple, but comprehensive, self-administered FFQs to study nutrient exposures in large-scale epidemiological studies of the elderly and to expect reasonably high FFQ response rates.

Aged↗

PubMed1994

Short- and long-term reproducibility of QT, QTc, and QT dispersion measurement in healthy subjects.

The study investigated interobserver and intrasubject reproducibility of QT interval duration and dispersion measured in standard 12-lead ECGs recorded at 25 mm/sec. Twenty-eight healthy volunteers were studied. Each underwent four ECG recordings, which were performed 1, 7, and 30 days apart. Two independent observers analyzed each ECG record. In each lead with a distinguishable T wave pattern, the RR interval, Q-peak of T interval, and Q-end of T interval were measured using a digitizing board with a 0.1-mm resolution. From each recording the following measures were derived: the maximum, minimum, and mean QT interval; maximum, minimum, and mean heart rate corrected QT interval (QTc); QT and QTc dispersion (the difference between the maximum and minimum QT interval among the 12 leads); and adjusted QT and QTc dispersion (dispersion divided by the square root of the number of leads measured). The interobserver and short-term (1 day) and long-term (1 week and 1 month) reproducibility of individual indices was assessed by computing the relative errors and comparing them by a standard sign test. In addition, the distributions of maximum and minimum QTc values among electrocardiographic leads, and the differences between QT-end and QT-peak based measurements were investigated. The results showed that: (1) the measurement of the QT interval from standard ECG recordings is feasible and not operator dependent (interobserver relative error < 4%); (2) the duration of the QT interval in healthy volunteers is stable and its short- and long-term reproducibility is high (intrasubject relative error < 6%); (3) parameters that characterize dispersion of the QT interval in the 12-lead ECG are highly nonreproducible, both between subsequent recording (relative error of 25%-35%) and between observers (relative error 28%-33%), the reproducibility of QT dispersion is significantly lower than that of QT duration (P < 0.01); and (4) the duration of the entire QT interval correlates only weakly with the duration of the Q-peak of T interval.

Adult↗

PubMed1996

Immediate and day-to-day reproducibility of the signal-averaged electrocardiogram in patients with coronary artery disease.

The purpose of this study was to prospectively evaluate the immediate (5 minutes) and short-term (1 day) reproducibility of the signal-averaged electrocardiogram (SAECG) in patients with coronary artery disease. A total of 59 consecutive patients with coronary artery disease (50 male, 9 female, mean age 59 +/- 13 years) were included. Analysis was performed using a commercially available system with high-pass filters of 25, 40, and 80 Hz without any change in electrode position. The following time-domain parameters were measured: (1) total filtered QRS duration; (2) duration of high-frequency low-amplitude signals (HFLA); and (3) root-mean-square voltage of the terminal 40 ms of the QRS complex (RMS40). Correlation between pairs of measurements was excellent, ranging from 0.91-0.99 for QRS and HFLA duration, and from 0.83-0.98 for RMS40 value. However, the range of differences was wide for all parameters, especially at 25 and 80 Hz, revealing marked individual variations in selected cases. The immediate reproducibility of an initially normal SAECG was 95% at 25 Hz, 100% at 40 Hz, and 81% at 80 Hz; figures for an initially abnormal SAECG were 89%, 91%, and 93%, respectively, and the coefficient of agreement kappa was highest at 40 Hz than at 25 or 80 Hz. Discordant results were most frequently observed in patients with borderline values, or in cases with nonsimilar residual noise levels. In conclusion, the immediate and day-to-day reproducibility of the SAECG is excellent in patients with chronic stable coronary artery disease. However, individual variations are observed in selected cases, leading to modification in interpretation of the result. For this reason, individual reproducibility should be considered before evaluating the effect of any therapeutic intervention on the SAECG, especially in patients with borderline values of the quantitative parameters of the SAECG.

Coronary Disease↗

PubMed1998

Comparative reproducibility of QT, QT peak, and T peak-T end intervals and dispersion in normal subjects, patients with myocardial infarction, and patients with hypertrophic cardiomyopathy.

Abnormal repolarization is associated with arrhythmogenesis. Because of controversies in existing methodology, new computerized methods may provide more reliable tools for the noninvasive assessment of myocardial repolarization from the surface electrocardiogram (ECG). Measurement of the interval between the peak and the end of the T wave (TpTe interval) has been suggested for the detection of repolarization abnormalities, but its clinical value has not been fully studied. The intrasubject reproducibility and reliability of automatic measurements of QT, QT peak, and TpTe interval and dispersion were assessed in 70 normal subjects, 49 patients with acute myocardial infarction (5th day; MI), and 37 patients with hypertrophic cardiomyopathy (HC). Measurements were performed automatically in a set of 10 ECGs obtained from each subject using a commercial software package (Marquette Medical Systems, Milwaukee, WI, U.S.A.). Compared to normal subjects, all intervals were significantly longer in HC patients (P < 0.001 for QT and QTp; p < 0.05 for TpTe); in MI patients, this difference was only significant for the maximum QT and QTp intervals (P < 0.05). In both patient groups, the QT and QTp dispersion was significantly greater compared to normal subjects (P < 0.05) but no consistent difference was observed in the TpTe dispersion among all three groups. In all subjects, the reproducibility of automatic measurement of QT and QTp intervals was high (coefficient of variation, CV, 1%-2%) and slightly lower for that of TpTe interval (2%-5%; p < 0.05). The reproducibility of QT, QTp, and TpTe dispersion was lower (12%-24%, 18%-28%, 16%-23% in normal subjects, MI and HC patients, respectively). The reliability of automatic measurement of QT, QTp, and TpTe intervals is high but the reproducibility of the repeated measurements of QT, QTp and TpTe dispersion is comparatively low.

Adult↗

PubMed1998

Reproducibility of the adenosine-5'-triphosphate test in vasovagal syndrome.

INTRODUCTION: Adenosine-5'-triphosphate (ATP) provokes negative chronotropic and dromotropic vagal effects. In vasovagal syndrome, ATP test (20-mg i.v. bolus infusion) represents a promising technique for identifying patients at risk of severe cardioinhibitory response of vagal origin. The electrocardiographic and related symptom reproducibility of this descriptive test must be assessed. METHODS AND RESULTS: In order to achieve this objective, ATP tests were performed twice in 80 patients (44 men, 36 women; mean age 72.3+/-12.2 years) by using the recently published test procedure and criteria of positivity. The second test was repeated shortly after the initial test (mean: 7 days) in 43 patients and long-term (mean: 3.7 years) in 37 patients. The initial ATP test provoked a cardiac pause > 10 seconds in 31 patients (39%) and a short cardiac pause (< or =10 sec) or no pause in 49 patients (61%). The electrocardiographic outcome was reproduced during the second ATP test in 36 patients (84%) of the short-term group and in 29 patients (78%) of the long-term group. Similarly, symptoms were reproduced in 38 patients (88%) of the short-term group and 29 patients (78%) of the long-term group, reflecting the severity of the electrocardiographic outcome. CONCLUSION: The negative chronotropic and dromotropic vagal effect of ATP can be reproduced short term and long term in 84% and 78% of patients, respectively. Associated symptoms were related to the severity of the electrocardiographic outcome.

Adenosine Triphosphate↗

PubMed2001

Reproducibility of proton magnetic resonance spectroscopy imaging measurements of normal human hippocampus at 1.5 T: clinical implications.

The authors investigate the reproducibility of metabolite signals measured with proton magnetic resonance spectroscopy (1H-MRS) acquired from the human hippocampus in controls and in a phantom. Two 1H-MRS studies separated by 3 weeks were performed in 8 healthy volunteers and in a phantom. N-acetyl compounds (NA), choline (Ch), and creatine (Cr) peak areas and ratios were measured and compared using percentage variation, and Pearson Correlation Coefficient at the level of every voxel, the level of 1 hippocampus (5 voxels), and the level of 2 hippocampi (10 voxels). Sensitivity for observing clinically significant between-session 1H-MRS changes was evaluated using the reliable change index. Reproducibility measures for metabolite peak areas were only moderately concordant with percentage variation ranging from 14% to 20% for NA, Cho, and Cr. Stability was much improved when NA ratios and sum of multiple voxels were considered. Between-session NA/(Cho + Cr) changes greater than 22%, 12%, and 10% in one given participant can be detected with a 90% confidence interval when considered at the single-voxel level, the level of a single hippocampus, or the level of both hippocampi, respectively. Left-right asymmetry indices showed similar and limited inter-hemispheric asymmetry in repeated examination. This study suggests that 1H-MRS reproducibility performance is adequate for the study and monitoring of human hippocampus function when NA ratios and the sum of multiple voxels are considered. Individual metabolite peaks and single-voxel measurements have low reproducibility at 1.5 T and should be used only with clearly established statistical parameters.

Adult↗

PubMed1990

Reproducibility of microbiological samples from periodontal pockets.

Duplicate microbiological samples, were taken 1 week apart using the paper point technique from a total of 112 untreated periodontal pockets greater than 6 mm deep in 16 adult periodontal patients. Duplicate samples were also obtained from these sites 6 months following a therapy of oral hygiene instruction and supra- and subgingival debridement. The reproducibility of the total viable counts and the reproducibility of the proportions of various groups or species of microorganisms were studied from these duplicate samples. The results demonstrated an acceptable degree of reproducibility for the recovery of Actinobacillus actinomycetemcomitans and Bacteroides gingivalis. For the total viable counts and for the other investigated bacterial groups, including Bacteroides intermedius, unacceptable levels of reproducibility were observed.

Actinobacillus↗

PubMed2004

Reproducibility and accuracy of automated probe measurements of gingiva and bone levels on stone casts following guided bone regeneration treatment.

OBJECTIVES: For evidence-based evaluation of guided bone regeneration (GBR), accurate registration of changes in gingiva and bone levels is needed. A new method is introduced and evaluated. METHODS: In a clinical trial with 30 patients, alginate impressions of the surgical area including the interproximal gingiva and alveolar bone at the adjacent teeth were made in duplicate prior to and during GBR surgery, fixture installation and abutment connection. Poured in hard stone, the casts were used for repeated measurements of the level of the free gingival margin and the alveolar bone with an automated probe (Florida disc-probe(R)), using the incisal edge as a fixed reference point. The reproducibility and accuracy of these measurements were evaluated by means of the Intraclass Correlation Coefficients and Generalizability Theory. The effect of treatment was evaluated by multivariate analysis of variance. RESULTS: Generalizability Theory indicated a high accuracy of the gingiva- and bone-level measurements: the Intraclass Correlation Coefficients for gingiva and bone levels were 0.99 and 0.98, respectively. The intra-cast reproducibility was 0.09+/-0.07 mm (mean+/-SD) and the inter-cast reproducibility was 0.10+/-0.09 and 0.20+/-0.07 mm for gingiva and bone levels, respectively. Clinical applicability is demonstrated by the fact that manova revealed on average a small but highly significant (p=0.001) effect of the staged surgical intervention on the gingiva and bone levels at the adjacent teeth. CONCLUSION: It is concluded that the presented method makes it possible to evaluate reproducibly and accurately changes in gingiva and bone levels for GBR studies.

Alveolar Bone Loss↗

PubMed1995

The measure of life-time alcohol consumption in patients with cirrhosis: reproducibility and clinical relevance.

Our aims were to design a reproducible method of measuring life-time alcohol consumption in patients with cirrhosis, and to assess the risk of liver decompensation associated with alcohol intake using a case-control design and a multivariate analysis. We studied 439 patients ("cases") with decompensated cirrhosis, and 233 with compensated cirrhosis ("controls"). Mean life-time daily amount and duration of alcohol intake were measured by a standardized questionnaire, whose reproducibility, assessed by interviewing 75 relatives, was 70% for daily alcohol intake and 84% for duration of intake. Better reproducibility was found by re-interviewing patients at discharge from hospital. Daily alcohol intake was significantly higher in males, younger patients and patients with liver decompensation. After stratification according to the average life-time daily alcohol intake, we found a significant increase in the risk of liver decompensation from 125 g ethanol intake per day onwards. No association was found between duration of alcohol intake and risk of liver decompensation. We conclude that alcohol intake can be reliably and reproducibly measured: in patients with cirrhosis, increased alcohol intake is associated with increased risk of liver decompensation, with a significant dose-effect above a daily intake of 125 g ethanol.

Adult↗

PubMed1994

Microbiologic tests in epidemiologic studies: are they reproducible?

Microbiologic assessments are often included in longitudinal studies to elucidate the significance of the association of certain Gram-negative bacteria and the development of periodontal diseases. In such studies, the reliability of methods is crucial. There are several methods to identify putative pathogens, and some of them are commercially available. The purpose of the present study was to compare the reproducibility of four different methods for detecting Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, and Prevotella intermedia in order to evaluate their usefulness in epidemiologic studies. The test panel consisted of 10 young subjects and 10 adult periodontitis patients. Subgingival plaque was sampled from sites showing bone loss and "healthy" control sites. The four different methods for detecting the target bacteria were 1) cultivation, 2) Evalusite (a chair-side kit based on ELISA), 3) OmniGene, Inc, based on DNA probes, and 4) indirect immunofluorescence (IIF). The test procedure was repeated after a 1-wk interval and was performed by one examiner. Sites reported to be positive for a microorganism by any of the four methods at one or both examinations were considered to be positive for that organism and included in the analysis. The reproducibility of the four methods was low. The IIF and the cultivation methods showed somewhat higher reproducibility than did the commercial systems. A second test was done for Evalusite, three paper points for sampling being used instead of one as described in the manual. The reproducibility of the second test was improved, indicating that the detection level of the system may influence the reliability.

Adolescent↗

PubMed1989

Reproducibility of histomorphologic diagnoses with special reference to the kappa statistic.

Systems for classification and grading used in pathology should ideally be biologically meaningful and at least be reproducible from one pathologist to another. A statistical method to evaluate reproducibility (non-chance agreement) for several observers using nominal or ordinal categories has been developed and refined over the past few decades--the kappa statistic. A high level of observed agreement among different pathologists can either signify a high level of reproducibility, if agreement by chance is low, or express a low level of reproducibility, if agreement by chance is almost as high as the observed agreement. Therefore, the observed agreement says nothing in itself, unless it is low. The kappa value, however, indicates how much better the observers are compared to a throw of the dice, and therefore gives the real credit to the agreement which was found. We have developed a user-friendly computer program for calculating inter- and intra-observer agreement of 2 or more observers. By calculating associations between different categories and different observers, the statistic furthermore obtains a function close to the parameter of accuracy. We recommend the use of the above method before a set of nominal or rank scale parameters are used for deciding prognosis and treatment of patients. By submitting a diskette the computer program will be available at no cost.

Histological Techniques↗

PubMedDate not supplied

Doppler echocardiography in the dog: measurement variability and reproducibility.

Serial Doppler echocardiographic examinations were carried out in random order on six boxer dogs, on 3 separate days, by two experienced Doppler echocardiographers, to assess measurement variability and reproducibility of 65 parameters. Large numbers of parameters exhibited significant differences for each of the categories of intraobserver, interobserver, interday and interoperator. The coefficients of variation for all parameters measured ranged from 5.03 to 46.43%, but most were less than 20%. In general, least variation was found for the intraobserver category, and the best reproducibility for M-mode and left ventricular volumetric data. The worst reproducibility was found for tricuspid inflow and pulmonary venous flow measurements. The results of this study suggest differences greater than 20% for serial scans must be achieved to document genuine change, although the specific data should be consulted. Furthermore, variability and reproducibility are improved if a single experienced operator/observer acquires and measures serial scans.

Animals↗

PubMed2003

Reproducibility study of magnetic resonance image-based computational fluid dynamics prediction of carotid bifurcation flow.

The importance of shear stress in the initiation and progression of atherosclerosis has been recognized for some time. A novel way to quantify wall shear stress under physiologically realistic conditions is to combine magnetic resonance imaging (MRI) and computational fluid dynamics. The present study aims to investigate the reproducibility of the simulated flow by using this combined approach. The right carotid bifurcations of eight healthy subjects were scanned twice with MRI within a few weeks. Three-dimensional geometries of the vessels were reconstructed for each scan and each subject. Pulsatile flows through these models were calculated to assess errors associated with the predicted flow parameters. This was done by comparing various wall shear stress indices, including the time-averaged wall shear stress (WSS), oscillating shear index (OSI), WSS Gradients (WSSG) and WSS Angle Deviation (WSSAD). Qualitatively, all the wall shear parameters proved to be highly reproducible. Quantitatively, the reproducibility was over 90% for OSI and WSSAD, but less impressive (60%) for other parameters. Our results indicated that WSS and WSSG values were extremely sensitive to subtle variations in local geometry and mesh design, particularly in regions around the bifurcation apex where WSS values were high and least reproducible.

Adult↗

PubMed2003

CT evaluation of patient deep inspiration self-breath-holding: how precisely can patients reproduce the tumor position in the absence of respiratory monitoring devices?

The aim of the present study was to evaluate the reproducibility of tumor position under patient deep inspiration self-breath-holding in the absence of respiratory monitoring devices, as well as to compare the reproducibility of deep inspiration self-breath-holding on the verbal command of a radiation technologist (Passive mode) with that initiated by patients' own estimation (Active mode). Twenty patients with lung cancer were shown how the tumor and diaphragm move during the respiration cycle. Patients were instructed to hold their breath during deep inspiration and reproduce identical tumor position as well as possible either by the Active mode or by the Passive mode. After patients had practiced self-breath-holding during deep inspiration, a set of three CT scans was obtained for each of the two modes of self-breath-holding (6 CT scans total) to obtain randomly timed images of 2 mm thickness in the vicinity of the tumor. The first three scans were performed during breath-hold using the Active mode, and next three scans were using the Passive mode. Maximum difference in tumor position for the three CT scans was then calculated along three axes: cranial-caudal (C-C); anterior-posterior (A-P); and right-left (R-L). In the 20 patients who underwent analysis of self-breath-holding, mean maximum difference in tumor position obtained under breath-hold using the Active and the Passive modes were: 2.2 and 3.1 mm along the C-C axis; 1.4 and 2.4 mm along the A-P axis; and 1.3 and 2.2 mm along the R-L axis, respectively. These differences in all axes were significantly smaller (p<0.05) for the Active mode than for the Passive mode. Most tumors displayed maximal respiratory movement along the C-C axis, and minimal movement along the R-L axis, but tumors located in the upper lung displayed maximal movement along the A-P axis. Significant correlation (p<0.05) was observed between differences along three axes in either mode of breath-hold. In conclusion, the reproducibility of tumor position under self-breath-holding by patients during deep inspiration after sufficient practice and in the absence of respiratory monitoring devices was satisfactorily accurate, and differences in tumor position were smaller under breath-holding using the Active mode than using the Passive mode. We believe this new technique is likely to prove extremely useful for the irradiation of lung tumors with a small internal margin and for reduced proportion of high-dose irradiated normal lung to total lung volume.

Artifacts↗