Although the radiation dose levels in dental radiography are low, exposure to radiation should be reduced whenever possible. One of the options to reduce radiation dose to the patient is to reduce the size of the primary imaging field [1,2]. In dental radiography, circular and rectangular beam-indicating device (BID) are used, whose form of collimation is the same as their shape [3,4]. According to the literature [1-5] a rectangular BID with rectangular collimation or an additional rectangular collimation attached to a circular BID reduces the...

The research was performed on intraoral dental X-ray unit. The round collimation measurements were performed on a round BID and measurements for the rectangular collimation with an additional rectangular collimation, which is attached to the end of the round BID (image 1). A circular collimation produced an image with a diameter of 6 cm and rectangular collimation with size of 4 cm × 5 cm (image 2). The measurements of DAP were made using external DAP meter which was installed directly under the PID (position...

When using a rectangular collimation, DAP was reduced by 32 % compared to a circular collimation, statistically significant differences were shown (p = 0,008). The difference between DAP average for the use of rectangular and circular collimation was 0.55 µGy m^2 (31.8 %), with statistically significant differences (p < 10^-3). The difference between results of literature [1,5] and this research is possible because of different size of circular collimation. The diameter of the circular collimation mentioned in literature was about 1 cm larger.

The results showed that the use of a rectangular collimation in intraoral dental radiology reduces DAP by 32 % compared to the round collimation. Base on that conclusion we recommend the usage of rectangular collimation in intraoral radiography.

1. American Dental Association Council on Scientific Affairs (2006). The use of dental radiographs: Update and recommendations. Association report. JADA 137 (9): 1304–1312. http://www.ncradiation.net/xray/documents/dental%20ADArad.pdf. <24.1.2015> 2. American Dental Association Council on Scientific Affairs (2001). An update on radiographic practices: information and recommendations. Association report. Jada 132(12): 234 –8. http://www.limoli.com/fileTamer/An%20Update%20On%20Radiographic%20Practices.pdf. <24.1.2015> 3. Langlais R (2004). A special report – Rectangular collimation, No longer a matter of choice. Interactive Diagnostic Imaging. http://www.idixray.com/media/pdf/Tru-Align%20Special%20Report.pdf. <24.1.2015> 4. Parrott LA, Ng SY (2011). Research – A comparison between bitewing radiographs taken...