The Effect of the Film-to-Focus Distance (FFD) Method on the Optical Density of the Organs and Anatomical Interest Parts in the Thoracic Cage

Authors

Keywords:

Optical density, Film-Focal Distance (FFD), Chest X-Ray (CXR), Thoracic cage, RaySafe Thin-X RAD, Dosemeter

Abstract

The effect of the Film-Focal Distance (FFD) technique on the optical density of the parts of anatomical interest and the organs within the thoracic cage was determined to identify a quality radiograph that is required by the Radiologists to accurately interpret and conclude the diagnosis from Chest X-ray (CXR) films. A PHILIPS MCD-105 mobile portable X-ray machine with a maximum voltage of 105 kVp was used in this study. AGFA X-ray films were used to obtain all the chest radiographs. A perspex phantom was constructed to house the rib cage of a human adult obtained from the anatomy laboratory. The whole phantom arrangement was to simulate the chest part of an adult human. The phantom was exposed five times, maintaining a constant voltage of 70 kV and a tube load of 10 mAs, by varying the FFDs at 110, 120, 130, 140, and 150 cm. A RaySafe Thin-X RAD dosemeter was used to determine the doses delivered to the Phantom. An X-Rite 331 transmission densitometer was used to determine the optical densities of the required areas. It was noted that both the FFDs and optical densities of the recorded areas have an inverse relationship, confirming that FFD has a significant effect on the quality of any X-ray film in chest X-ray examinations. Even though the radiograph at FFD 150 cm had the best contrast of them all due to low exposure, the radiograph at FFD 140 cm was found to give the optimum image quality of the parts of anatomical interest and the positions of the organs enclosed in the rib cage, with a dose even lower than the internationally accepted maximum value.

Dimensions

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Published

2025-09-22

How to Cite

Nabasu, S. E., Dang, D. Y., Weng, Y. C., Dembo, J. S., Joseph, P. B., Joseph, D. Z., Sirisena, U. A. I., Kyense, D. K., Songden, S. D., & Freeman, N. (2025). The Effect of the Film-to-Focus Distance (FFD) Method on the Optical Density of the Organs and Anatomical Interest Parts in the Thoracic Cage. Nigerian Journal of Physics, 34(3), 154-161. https://doi.org/10.62292/

Issue

Vol. 34 No. 3 (2025): Nigerian Journal of Physics - Vol. 34 No. 3

Section

Articles
Copyright & Licensing

How to Cite

Nabasu, S. E., Dang, D. Y., Weng, Y. C., Dembo, J. S., Joseph, P. B., Joseph, D. Z., Sirisena, U. A. I., Kyense, D. K., Songden, S. D., & Freeman, N. (2025). The Effect of the Film-to-Focus Distance (FFD) Method on the Optical Density of the Organs and Anatomical Interest Parts in the Thoracic Cage. Nigerian Journal of Physics, 34(3), 154-161. https://doi.org/10.62292/