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. 2019 Feb;48(2):20180183.
doi: 10.1259/dmfr.20180183. Epub 2018 Nov 7.

Kerma area product (KAP) and scatter measurements for intraoral X-ray machines using three different types of round collimation compared with rectangular beam limiter

Dennise Magill  1 , Nhan James Huu Ngo  2 , Marc A Felice  1 , Mel Mupparapu  2
Affiliations

Kerma area product (KAP) and scatter measurements for intraoral X-ray machines using three different types of round collimation compared with rectangular beam limiter

Dennise Magill et al. Dentomaxillofac Radiol. 2019 Feb.

Abstract

Objectives:: The objective of the study was to determine the radiation dose reduction achieved when rectangular collimation was used on various round collimators. In addition, we evaluated the tissue doses imparted to various head and neck organs.

Methods:: To evaluate the variation in radiation output based on the variable geometric configurations, the kerma area product (KAP) was measured using a commercially available KAP-meter with an internal ion chamber capable of detecting both radiation dose (µGy) and the primary X-ray beam area. The KAP was measured using standard 20.4, 25.7, and 31.7 cm2 round collimators with and without rectangular X-ray field restrictors. To evaluate the potential change in patient scatter radiation dose, an adult head phantom was loaded with thin strips of gafchromic film. A full mouth X-ray series was acquired with various geometric configurations. The films were quantified using a calibration factor to yield absorbed organ doses for the eyes, thyroid, and salivary glands.

Results:: With the use of rectangular collimator, the KAP for a 31.7 cm2 round collimator was reduced by up to 60% while the 20.4 cm2 round collimator elicited a reduction from up to 40%. In the organ study, results of up to 81% reduction in scatter radiation dose were observed.

Conclusions:: Although, US FDA regulations allow a maximum beam size of 38.5 cm2 on the patient skin, this study suggests that the use of rectangular collimators provide clinically relevant dose reduction for patients, even when using smaller round collimation, hence the use of rectangular collimation for all intraoral radiographic procedures is highly recommended.

Keywords: rectangular collimation; scatter; collimation; dose; kerma air product; round collimation.

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Figures

Figure 1.
Figure 1.
The experimental setup with collimator placed in contact with the PDC for KAP measurements, and the Dentsply and Carestream rectangular primary beam limiters installed for these measurements. KAP, kerma area product; PDC, patient dose calibrator.
Figure 2.
Figure 2.
The adult phantom head used with individual slices and simulated organ locations marked numerically with corresponding wells for Gafchromic film placement.
Figure 3.
Figure 3.
The results from the scatter radiation dose for head and neck organs in the (A) 31.7 cm2, (B) 25.7 cm2 and (C) 20.4 cm2 round collimations versus the 12.0 cm2 rectangular collimation.
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References

    1. US Food and Drug Administration Performance standards for Ionizing radiation emitting products, 21 CFR 1020 (US. Government Printing Office, Washington). 2018. Available from: https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/CFRSearch.cfm?C... [Updated 2017/08/14. Cited 2018, May 1].
    1. The American Dental Association Council on Scientific Affairs, Food and Drug Administration Dental Radiographic Examinations: Recommendations for patient selection and limiting radiation exposure (U.S. Government Printing Office, Washington). 2018. Available from: https://www.ada.org/en/member-center/oral-health-topics/x-rays [Updated 2018/03/07. Cited 2018 May 2].
    1. National Council on Radiation Protection and Measurement NCRP Report 145: Radiation Protection in Dentistry. Bethesda. Bethesda, MD: The British Institute of Radiology.; 2003. 41.
    1. Gibbs SJ, Pujol A, Chen TS, Malcolm AW, James AE. Patient risk from interproximal radiography. Oral Surg Oral Med Oral Pathol 1984; 58: 347–54. doi: 10.1016/0030-4220(84)90066-5 - DOI - PubMed
    1. Committee on the biological effects of ionizing radiations, Board of radiation effects research, Commission on life sciences, National Research Council Health effects of exposure to low levels of Ionizing radiation : BEIR V. Washington: The British Institute of Radiology.; 1996. pp 1–49.