A comparison of modulation transfer function of indirect digital radiography systems

Main Article Content

Banjong Kheonkaew
Kridsanapan Srimongkon
Thawatchai Prabsattroo
Wichai Witchathorntragul

Abstract

Background: There are several parameters to characterize the quality of digital image. Resolution is one of the main parameters of an image quality. Modulation transfer function (MTF) is a quantitative measurement describes image resolution properties of an imaging system as a function of the spatial frequency. Several reports compared the spatial resolution between direct and indirect digital radiography (DR) systems proved that direct DR systems had better spatial resolution. Moreover, they also compared the different phosphor detectors of indirect DRs. However, to our knowledge, there is no report that compares the same gadolinium oxysulfide (GOS) phosphor detectors of indirect DR from different DR system manufacturers.


Objectives: To compare MTF of flat panel detectors (FPDs) indirect conversion using GOS phosphor with fixed focal spot size under radiation beam condition according to International Electrotechnical Commission (IEC) RQA5 standard.


Materials and methods: Three indirect FPDs from 3 DR manufacturers i.e. detector A, detector B and detector C were used in this study. Measurement tests for spatial resolution evaluating were performed by means of a set of 30 groups of bar patterns with different spatial frequencies which vary increasing order and express as line pairs per unit distance (lp/mm). MTF can be performed from a bar pattern within the image file by elaboration software AutoPia (Auto Phantom image analysis). Frequency at the 0.1 point of MTF was applied with this limiting spatial resolution.


Results: Three FPDs had similar MTF shape. All of MTF values from detectors were decreased with increasing spatial frequency from detector A, B, and C, respectively. This can be sorted in descending order as follows. MTF showed that detector A demonstrated both the highest contrast resolution and spatial resolution. Nevertheless, detector B and C had the same contrast resolution, yet the spatial resolution of detector B was better than that of detector C. Spatial frequency reflects the limiting spatial resolution (MTF=0.1) of detector A, B, and C, at 4.40, 4.02, and 3.77 lp/mm, respectively.


Conclusion: The bar pattern method with an automatic software analysis can be simply obtained MTF result. Test of MTF in beam quality as recommended in IEC RQA5 standard of three FPDs show that spatial resolution sorted in descending order were through detector A, B and C, respectively.

Downloads

Download data is not yet available.

Article Details

How to Cite
Kheonkaew, B., Srimongkon , K., Prabsattroo , T., & Witchathorntragul, W. (2020). A comparison of modulation transfer function of indirect digital radiography systems. Journal of Associated Medical Sciences, 53(3), 1-7. Retrieved from https://he01.tci-thaijo.org/index.php/bulletinAMS/article/view/241259
Section
Radiologic Technology

References

[1] Zannoli R, Bianchini D, Maschio MC. Performance evaluation of detector for digital radiography. Bologna: Alma Mater Studiorum Università di Bologna; [n.d.].

[2] Borasi G, Nitrosi A, Ferrari P, Tassoni D. On site evaluation of three flat panel detectors for digital radiography. Med Phys 2003; 30: 1719–31.

[3] Samei E, Flynn MJ. An experimental comparison of detector performance for direct and indirect digital radiography systems. Med Phys 2003; 30: 608–22.

[4] Alsleem H, Davidson R. Quality parameters and assessment methods of digital radiography images. Radiographer 2012; 59: 46–55.

[5] Williams MB, Krupinski EA, Strauss KJ, Breeden WK, Rzeszotarski MS, Applegate K, et al. Digital radiography image quality: image acquisition. J Am Coll Radiol 2007; 4: 371–88.

[6] Honey I, Mackenzie A, Doyle P. Measurement of the performance characteristics of diagnostic x-ray systems: digital imaging systems. 2nd ed. London: Institute of Physics and Engineering in Medicine; 2010.

[7] Das S, Mukherjee D, Abdulla K. Digital radiography assessing image quality [Internet]. 2020 [cited 2020 Feb 18]. Available from: https://bit.ly/2SPRiWA.

[8] Seeram E. Plat-panel digital radiography. In: Digital radiography: physical principles and quality control. 2nd ed. Singapore: Springer; 2019: 65–8.

[9] Vaishnavi S, Salini GI, Shoukath S, Ravindran VR. Performance analysis of flat panel detector and film digitizer based on modulation transfer function. Proceedings of the National Seminar & Exhibition on Non-Destructive Evaluation; 2009 Dec 10-12; Tiruchirappalli, India.

[10] Alvarez M, Alves AFF, Bacchim N, Pavan ALM, Rosa MED, Miranda JRA, et al. Comparison of bar pattern and edge method for MTF measurement in radiology quality control. Rev Bras Fis Med 2015; 9(2): 2–5.

[11] Schaefer-Prokop C, Neitzel U, Venema HW, Uffmann M, Prokop M. Digital chest radiography: an update on modern technology, dose containment and control of image quality. Eur Radiol 2008; 18: 1818–30.

[12] Rivetti S, Lanconelli N, Bertolini M, Nitrosi A, Burani A. Characterization of a clinical unit for digital radiography based on irradiation side sampling technology. Med Phys 2013; 40: 101902. doi: 10.1118/1.4820364.

[13] Gomi T, Koshida K, Miyati T, Miyagawa J, Hirano H. An experimental comparison of flat-panel detector performance for direct and indirect systems (initial experiences and physical evaluation). J Digit Imaging 2006; 19: 362–70.

[14] Jeong HW, Min JH, Yoon YS, Kim JM. Investigation of physical imaging properties in various digital radiography systems. J Radiol Sci Technol 2017; 40: 363–70.

[15] Leeds Test Objects. TOR CDR [Internet]. 2020 [cited 2020 Feb 19]. Available from: https://bit.ly/2vOUo57.

[16] MediaWiki. AutoPIA [Internet]. 2016 [cited 2020 Feb 19]. Available from: https://bit.ly/39Lgu7p.

[17] Andria G, Attivissimo F, Lanzolla A, Guglielmi G, Francavilla M. Quality assessment in radiographic images. In: Proceedings of the 3rd IMEKO TC13 Symposium on Measurement in Biology and Medicine "New Frontiers in Biomedical Measurements; 2014 Apr 17-18; Lecce, Italy. Red Hook (NY): International Measurement Confederation: p. 79–84.

[18] Droege RT, Morin RL. A practical method to measure the MTF of CT scanners. Med Phys 1982; 9: 758–60.

[19] Marshall NW, Monnin P, Bosmans H, Bochud FO, Verdun FR. Image quality assessment in digital mammography: part I. Technical characterization of the systems. Phys Med Biol 2011; 56: 4201–20.

[20] Samei E, Ranger NT, Dobbins JT, Chen Y. Intercomparison of methods for image quality characterization. I. Modulation transfer function. Med Phys 2006; 33: 1454–65.

[21] Leong DL, Rainford L, Zhao W, Brennan PC. IEC 61267: Feasibility of type 1100 aluminium and a copper/aluminium combination for RQA beam qualities. Phys Med 2016; 32: 141–9.

[22] Bertolini M, Nitrosi A, Rivetti S, Lanconelli N, Pattacini P, Ginocchi V, et al. A comparison of digital radiography systems in terms of effective detective quantum efficiency. Med Phys 2012; 39: 2617–27.

[23] Kudo K, Osanai M, Hirota J, Abe T, Matsuoka M, Naraki S, et al. Comparison between irradiation side sampling flat-panel detector system and computed radiography system for reduction of radiation exposure. Radiat Emerg Med 2015; 4(2): 45–52.