Results
Fig. 5 shows the results of evaluating the correlation between average number of years of experience and pass rates in the written test (Left) and the abnormal finding detection test (Right).
The results of the regression analysis were as follows: Slope value,
-0.004; intercept,
0.965; and correlation coefficient R = 0.105 (P-value = 0.71) in the written test; and slope value,
0.039; intercept,
0.355; and correlation coefficient R = 0.558 (P-value = 0.03) in the abnormal finding detection test.
In Fig. 6 ,
the results of the written test were classified into four groups of years of experience: 2–5 years,
6–10 years,
11–20 years and 21 years or more.
The average score value of each was 2 - 5 years: 77.1,
6 - 10 years: 76.4,
11 - 20 years: 74.2,
over 20 years: 73.0.
The combinations other than "2–5 years" - "6–10 years" and "11 to 20" - "over 20 years",
there were significant difference (p <0.01).
In Fig. 7 ,
as in Figure 6,
the results of the abnormal finding detection test were classified according to the years of experience,
and the accuracy of the TP values was evaluated.
The average TP value of each group was: 2–5 years,
0.
922; 6–10 years,
0.930; 11–20 years,
0.
937; and over 20 years,
0.937.
In the combinations of "2–5 year" - "11–20 year " and "over 20 year ",
"6–10 year " - "11 –20 year ",
the differences were observed to be statistically significant (P < 0.01,
P < 0.01,
and P < 0.05,
respectively).
In Fig. 8 ,
the accuracy of the FP value was evaluated in the same way.
The average FP value of each group was: 2–5 years,
0.
465; 6–10 years,
0.430; 11–20 years; 0.
484; and over 21 years,
0.365.
In all results,
the mean FP value decreased significantly (P < 0.05) in the group with over 20 years of experience.
Discussions
This study examines the data from a 10-year record possessed by the Accreditation Council for Lung Cancer CT Screening.
The philosophy of the Accreditation Council for Lung Cancer CT Screening is "to guarantee lung cancer CT screening at a certain accuracy or higher anytime anywhere in Japan".5 The certification exam is the level least able to achieve this philosophy.
In this study,
the score of the written test,
TP value,
and FP value of the examinees will be considered from the viewpoint of the years of experience.
There was a weak correlation between the years of experience in the written exam and the passing rate ( Fig. 5 ,
Left).
Currently,
the certification organization discloses the publication of dedicated text6 as part of the preliminary learning and previous test questions,
without answers,
on the website of the Accreditation Council for Lung Cancer CT Screening.
By using these resources,
it is inferred that the examinees have obtained a learning effect that exceeds the acceptance level by 10 points or more,
regardless of the number of years of experience.
In addition,
aggregated results were classified into 4 groups of years of experience: 2–5 years; 6–10 years; 11–20 years; and 21 years or more.
When evaluated,
the written test scores decreased significantly with an increase in years of experience ( Fig. 6 ).
We suggest that this indicates a decline in knowledge of "academic knowledge" with an increase in number of years of experience.
In other words,
finishing school education,
biasing academic knowledge such as engineering knowledge,
image quality and dose evaluation of CT scanner for a long time in clinical seems to have affected the decrease in average score.
In the abnormal finding detection test,
the passing rate improved as the years of experience increased (Figure 5,
Right).
As shown by Figure 7.8,
both TP and FP values improved significantly as the years of experience increased.
The style and contents of the CT work of the radiological technologist has changed significantly,
due to shorter photographing time caused by multiple rows of CT detectors,
and higher picture quality due to the development of the sequential approximation application reconstruction method.
Single-slice CT scans,
the lesion was recognized from the thick-slice image,
and the thin-slice photographing was performed again.
Also,
The spread of “Picture Archiving and Communications” system was inadequate,
and the necessary range was outputted by "film".
These works have brought automatically improved the reading ability of the "radiological technologists".
In the era of 16-row multidetector CT scans,
there was a process of recognizing the lesion from the thick-slice image and reconstructing the thin-slice image from the same raw data.
However,
since the era of 64-row detectors,
the images provided by the thin slices has become the standard practice; consequently,
the role of image confirmation by the radiological technologist has markedly decreased,
and consequently the ability to detect abnormal findings has decreased.
The Accreditation Council for Lung Cancer needs to pay close attention to these data trends and issues.
The responsibilities of certified technologists will change because of changes in medical technology.
In order to maintain the standard of certified technologists,
it is always necessary to eliminate biases in knowledge,
to assess the balance between the foundation and clinical knowledge,
and to review the educational method.
For example,
in order to detect abnormal findings,
research and development of Computer-Aided Detection (CAD) has been promoted,
and some facilities have already adopted it.
In the future,
further improvements in accuracy can be expected by developing diagnostic support software equipped with artificial intelligence,
or deep learning.
In particular,
Deep Neural Networks have been designed to model cognitive patterns of human and animal cranial nerve circuits based on previous data,
and have been reported to be applied in clinical settings.7 We believe that training and practice using CAD is indispensable for maintaining the standard of certified technologists.