Phantom Study of Chest Radiography with Storage Phosphor, Selenium, and Film-Screen Systems

1996 ◽  
Vol 37 (1P1) ◽  
pp. 332-336 ◽  
Author(s):  
M. Kehler ◽  
K. Lyttkens ◽  
B. Andersson ◽  
P. Hochbergs ◽  
C.-G. Lindberg ◽  
...  
Keyword(s):  
Computed Radiography ◽  
The Other ◽  
Lung Tumour ◽  
Operating Characteristics ◽  
Storage Phosphor ◽  
Conventional Film ◽  
Screen System ◽  
Test Objects ◽  
Better Than ◽  
Storage Phosphor System

Purpose: Chest radiographs from 3 digital systems − 2 based on luminescent phosphors and one on selenium — and a conventional film-screen system were evaluated and compared. Material and Methods: Computed radiography (CR) has for the past years been dominated by a single manufacturer, but now several systems have been marketed. Using a chest phantom and, as test objects, 2 simulated tumours for the lung and mediastinum, respectively, and one object simulating pulmonary lines, a total of 400 exposures were made, 100 on each system. The test objects were placed randomly with a ratio of presence/absence of each object of about 50. Six radiologists participated, 2 residents and 4 staff members. A receiver operating characteristics (ROC) analysis was performed with construction of curves, and the difference between the curves was estimated with a 2-tailed paired t-test. Results and Conclusion: The selenium-based system performed significantly better for pulmonary line detection than all the other systems, and better than one storage phosphor system for the lung “tumour” (p<0.05), while one storage phosphor system was slightly better than the other in diagnosing all 3 test objects. The score for the film-screen system was only average.

Estimation of Visual Performance in Children with and without Binocular Anomalies by Means of a Computerised Coding Test

Perception ◽  
1997 ◽  
Vol 26 (1_suppl) ◽  
pp. 313-313
Author(s):  
T A Podugolnikova ◽  
G I Rozhkova ◽  
I S Kondakova
Keyword(s):  
Optimal Strategy ◽  
Reading Rate ◽  
The Other ◽  
Visual Performance ◽  
Hand Movements ◽  
Mental Work ◽  
Normal Children ◽  
The Difference ◽  
Test Objects ◽  
Better Than

Coding tests are regularly used to estimate the capacity for mental work in children entering school and for younger schoolchildren. The task of the child is to fill a special form by putting conventional symbols (codes) under the rows of test objects in accordance with a sample. The results of such testing reflect both visuomotor and intellectual capabilities since, on one hand, a subject has to perform fast eye and hand movements comparing test objects with the sample and drawing codes but, on the other hand, it is not forbidden to memorise codes and to use an optimal strategy for filling the form. In order to make the coding test more suitable for estimating purely visual capabilities, we evolved a computerised version in which codes were changing at each step, thus making their memorisation useless. Such a coding test was used in an examination of 22 children (age 6 – 7 years) with binocular anomalies (strabismus, amblyopia) from special kindergartens and 190 normal children (aged 6 – 9 years) (63 from kindergartens and 127 from school forms 1 – 3). The difference between children with binocular anomalies and normal children of the same age was statistically significant ( p<0.005). The average indices for normal children of different ages differed significantly increasing from 11.8 (at 6 years) to 24.6 (at 9 years) symbols per minute. The effect of learning was also evident: the indexes of 7-year-old children from the first school form were better than in children of the same age from a kindergarten. The correlation between coding indexes and reading rate was positive but rather weak (0.28) in 52 first-form children tested.

Lung nodule conspicuity using unsharp mask filters with storage-phosphor-based computed radiography

1997 ◽  
Vol 38 (1) ◽  
pp. 99-103 ◽  
Author(s):  
F. Li ◽  
S. Sone ◽  
K. Kiyono
Keyword(s):  
Roc Analysis ◽  
Computed Radiography ◽  
Lung Nodule ◽  
Low Frequency ◽  
Lung Nodules ◽  
Cancer Type ◽  
Storage Phosphor ◽  
Very Low Frequency ◽  
Unsharp Mask ◽  
Better Than

Purpose: To compare the performance of various types of unsharp mask filter applied in storage-phosphor-based computed radiography (SR), and to improve the detection of faint nodules of the lung cancer type. Material and Methods: A total of 120 SR radiographs were obtained by means of an anthropomorphous chest phantom and a combination of 3 types of small simulated nodule (5-mm sphere-shaped, and 5-mm and 10-mm hemisphere-shaped) placed on the phantom's surface. Eight combinations of nodule site were selected from 16 predetermined chosen sites, and 5 types of parameter were used for unsharp mask filtering. Eight observers evaluated the images, and the detectability of the lung nodules was evaluated from the images by a ROC analysis. Results: The visibility of the 10-mm hemispherical nodules was nearly equivalent at each site when 5 types of unsharp mask filter were used. The detection of the 5-mm nodules with mid-frequency suppressing and very-low-frequency enhancing filters was better than with a conventional (department standard) mid-frequency enhancing filter. Conclusion: Mid-frequency suppressing versions of the filter helped to demonstrate faint nodular opacity, which is often shown by early bronchogenic carcinoma. This filter could replace conventional filters in the detection of lung nodules.

Use of Storage Phosphors in Transmission Electron Microscopy

1991 ◽  
Vol 49 ◽  
pp. 984-985
Author(s):  
O. Boser
Keyword(s):  
Blue Light ◽  
Computed Radiography ◽  
Storage Phosphor ◽  
Analytical Instruments ◽  
Transmission Electron ◽  
Conventional Film ◽  
Electron Intensity ◽  
X Ray Computed ◽  
Storage Phosphors ◽  
Phosphor Plates

One of the most sophisticated analytical instruments, the transmission electron microscope (TEM), still records images on photographic plates. Attempts are made with video and charge coupled device (CCD) cameras to digitize the images and increase the sensitivity. An alternate technology to digitize images is based on storage phosphors widely used in medical x-ray computed radiography. For exposure to the electron beam, the storage phosphor plates are introduced in the microscope in place of conventional film. Digitization takes place in the read-out system that consists of a He/Ne laser that stimulates emission of blue light from the storage phosphor. The emitted blue light is proportional to the electron intensity that was incident at this point during exposure.

Closing the GAP—A 5Å Scanning Microscope

1969 ◽  
Vol 27 ◽  
pp. 6-7
Author(s):  
A. V. Crewe
Keyword(s):  
Normal Form ◽  
The Other ◽  
Resolving Power ◽  
Scanning Microscope ◽  
Conventional Microscope ◽  
Other Hand ◽  
Closing The Gap ◽  
Thermal Sources ◽  
Better Than ◽  
Transmission Microscope

We have become accustomed to differentiating between the scanning microscope and the conventional transmission microscope according to the resolving power which the two instruments offer. The conventional microscope is capable of a point resolution of a few angstroms and line resolutions of periodic objects of about 1Å. On the other hand, the scanning microscope, in its normal form, is not ordinarily capable of a point resolution better than 100Å. Upon examining reasons for the 100Å limitation, it becomes clear that this is based more on tradition than reason, and in particular, it is a condition imposed upon the microscope by adherence to thermal sources of electrons.

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