Interactive Interpretation of Anatomical Landmarks in Dental Radiology

Gerard C. H. Sanderink; Paul F. van der Stelt; Arjen J. van Rijn
Academic Center for Dentistry Amsterdam, The Netherlands

Computers in Healthcare Education Syposium: "Managing the Information Mosaic" April 26-28, 1995. Philadelphia PA 19107

ABSTRACT
A Windows and Authorware based CAL program for teaching the interpretation of anatomical landmarks in dental radiology was developed. The CD-ROM is designed to replace most of the group instructions in this subject. Several types of questions were used. Most attractive is the interactive response of the mouse in radiographic images. About 150 dental radiographs and drawings are available. The software can be used by dentists, dental students and hygienists.

PAPER

Introduction
The interpretation of radiographs plays an important role in the dental office. Several abnormalities are diagnosed solely by or with help of radiographs. For this reason the training in the interpretation of dental radiographs plays an important role in the curriculum of dental students and hygienists. Primarily a thorough knowledge of the anatomy of upper and lower jaws is required. However, more is needed to interpret the radiographic images. A radiographic image is not just determined by the anatomical landmarks but also for instance by the direction of the x-ray beam. Due to a different projection angle of the x-ray beam anatomical structures can be displaced relative to each other.

Students do need much practicing to get familiar with the normal anatomy at dental radiographs. At most dental schools in small student classes attention is paid to this subject. At the Dental School in Amsterdam students follow a practical course in making radiographs after their theoretical training is completed. Parallel to or before this course they have to take the CAL program on anatomical landmarks.

The CAL Program
The program consists of 4 lessons. Lesson 1 deals with the anatomical landmarks in the lower jaw. The upper jaw is anatomically and radiographically more complicated and the subject is therefore covered in three lessons. Each lesson consists of a number of questions, mainly about the radiographs shown in a separate window on the screen. See figure 1. Three different types of questions are being used: Multiple choice questions, a type of question with which the student is familiar from his exams. Furthermore questions where short open answers are required. In this case mostly the correct name of the landmark is asked for and finally a type where the student has to use the mouse and click at a specific area in the radiograph. This type of question or command is particularly attractive as this comes closest to 'reality' in interpreting dental radiographs, pointing to specific anatomic landmarks.

Figure 1.
An example of one of the questions. The mouse is needed to click at the anatomical structure in the radiograph.

Next to each answer feedback is given where the (in)correctness of the answer is explained. In all cases, also before answering the question, the student can ask for support or help. In that case hints are given (not the answers) and often a drawing is shown with the path of the x-rays relative to the skull. See also figure 2. It helps the student in finding the correct answers. Also a reference to a book is possible.

Figure 2.
A typical example of a help screen.

The program keeps track of the results of the students initial answers. During or at the end of the session an overview can be obtained of correct and incorrect answers. It is possible to jump to each individual question or to skip questions. The basic version of the program originates from 1988 when a DOS-version was developed. At that time a computer monitor for the texts and a tv-monitor for the images were used. The program was expanded and converted to a Windows environment in 1994 using Authorware Professional as an authoring tool.

In total more than 200 images (radiographs and drawings) are available in the program. 75 Megabyte storage is required. The development of the program was a cooperation of two teachers in dental radiology, an arts designer, a programmer and an expert in educational matters.

Educational environment
A practical course, where this CAI program forms part of, is given 12 times a year for small groups of eight students. Before the introduction of the CAI program approx. 8 hours were needed for group discussion on the interpretation of the dental radiographs. Primarily the frequent repetition of the course was reason to develop this CAI program. More time became available for patient activities.

In the new setting less than four hours are needed for the traditional instruction. Separately 2 hours are made available for students to follow the CAL program. The students are advised to do this before start of the clinical course. The function of the program is primarily to offer additional individual practice and drill facilities. A major advantage of the program is the reduction of 'contact' hours for the teacher and all students are faced individually with the educational materials.

Smooth operation of the CAI programs requires a 486 processor and 8 Mb internal memory, a SuperVGA screen (1024x786 dots) and a dual speed CD-Rom drive. The Dental School in Amsterdam has 10 of these units available for students. The student can take this course at any time upon availability of the units and can repeat this as often as desired. As during their clinical activities, sometimes appointments are being canceled by patients the students can fill the gaps in their regular program.

Dental hygienists also make use of these CAI programs. Although initially not intended for this group it appears to fit in well in their curriculum. In principle dental anatomy and radiographic landmarks are elementary parts of the curriculum which do not change by newer views or insights.

Experience
For a period of 6 months a log file was used to register the length of each CAL session and the answers. The incorrect answers were used to adjust irregularities and to add additional feed back. The average student needs 2 and a half hours to run the complete content of the lessons. In general students do appreciate the program very much. Students can handle the program without extensive explanations. They consider the contents interesting and the questions and explanations are in general clear. The level of the program was considered good by 95% of the students. It appeared that 56% of the student obtained a reasonable amount of new information and an additional 40% of the students learned very much.

A negative comment of the students was that after a number of mishits the correct answer was not made available. Maybe this will be changed in the future.

Conclusions
The program seems to meet the expectations. Students can exercise at a moment convenient for them and at a speed according to their skills. In particular the commands where they have to click at specific areas in the radiographs are successful as this approaches the clinical practice most.

According to the teacher students now have a higher entrance level than before the existence of the program. Students can find time to take the course at a time convenient to them. Teachers save several teaching hours a year, time which now can be used for patient related programs.