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Impact of Wedge Filters and Field Size on Skin Dose Distribution in X-ray Imaging

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This lecture explores how wedge filters and field size influence skin dose distribution during X-ray procedures. It highlights good and bad practices through various examples, emphasizing the importance of using wedge filters in right and left projections to improve image quality and reduce skin dose. The lecture also analyzes cases of insufficient wedge filter application, resulting in poor image quality and excessive radiation exposure. Additionally, the outcomes of multiple coronary angiographies and PTCAs are discussed to illustrate the practical implications in a clinical setting.

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Impact of Wedge Filters and Field Size on Skin Dose Distribution in X-ray Imaging

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  1. Examples of Good & Bad Practice:Effect of the wedge filterand field size in the skin dose distribution L 9.1

  2. Educational Objectives • How wedge filter & field size affect the skin dose • When and how to use wedge filter Lecture 9.1: Examples of good and bad practice

  3. Philips systems Lecture 9.1: Examples of good and bad practice

  4. Series 14: KVP: 88 Distance source to detector: 1048 Exposure time 8 X-ray tube current 467 Intensifier size 169.9 mm Positioner primary angle 5.2 (LAO) Positioner secondary angle 28.3 13 Sep 04; 40414 Example of lack of wedge filter use in a left projection. Image quality is not good (too bright in the upper left corner of the image) and in addition, more dose per frame than necessary. Bad practice!. Lecture 9.1: Examples of good and bad practice

  5. Series 21: KVP 87 Distance source to detector 995 Exposure time 8 X-ray tube current 472 Positioner primary angle - 41.1 (RAO) Positioner secondary angle 28.8 13 Sep 04; 40414 Example of lack of wedge filter use in a right projection. Image quality is not good (too bright in the upper right corner of the image) and in addition, more dose per frame than necessary. . Bad practice!. Lecture 9.1: Examples of good and bad practice

  6. Series : 6 (0008,0020) : Study Date : 21/09/2004 (0008,0080) : Institution Name : HOSPITAL SEVERO OCHOA (0008,1090) : Manufacturer's Model Name : INTEGRIS Allura Flat Detector (0018,0060) : KVP : 78.0 (0018,1110) : Distance Source to Detector : 1.08 (0018,1111) : Distance Source to Patient : 0.765 (?) (0018,1150) : Exposure Time : 6 (0018,1151) : X-ray Tube Current : 812 (0018,1510) : Positioner Primary Angle : -31.2 (0018,1511) : Positioner Secondary Angle : 32.2 Example of appropriate use of the wedge filter. (flat panel). Good practice!. Lecture 9.1: Examples of good and bad practice

  7. No wedge filter used. Image partially saturated. Bad practice!. Lecture 9.1: Examples of good and bad practice

  8. 0.5 mGy/fr 0.8 mGy/fr (60% more) Lecture 9.1: Examples of good and bad practice

  9. Use of wedge filter in right projections

  10. Effect of the wedge filter in skin dose distribution (right projections). Saving skin dose and improving image quality.Good practice!. Lecture 9.1: Examples of good and bad practice

  11. Lecture 9.1: Examples of good and bad practice

  12. Areas in red are saturated in the slow film. Skin dose more than 1.2 Gy. Lecture 9.1: Examples of good and bad practice

  13. Philips Integris: Use of wedge filter in left projections

  14. Effect of the wedge filter in skin dose distribution (left projections). Saving skin dose and improving image quality. Good practice!. Lecture 9.1: Examples of good and bad practice

  15. Lecture 9.1: Examples of good and bad practice

  16. Areas in red are saturated in the slow film. Skin dose more than 1.2 Gy. Lecture 9.1: Examples of good and bad practice

  17. Use of wedge filter in right and left projections

  18. Lecture 9.1: Examples of good and bad practice

  19. Lecture 9.1: Examples of good and bad practice

  20. Areas in red are saturated in the slow film. Skin dose more than 1.2 Gy. Lecture 9.1: Examples of good and bad practice

  21. Geometry with small field size

  22. Lecture 9.1: Examples of good and bad practice

  23. 68 cm2 28 cm2 26 cm2 Lecture 9.1: Examples of good and bad practice

  24. Areas in red are saturated in the slow film. Skin dose more than 1.2 Gy. Lecture 9.1: Examples of good and bad practice

  25. Geometry with big field size

  26. Lecture 9.1: Examples of good and bad practice

  27. 1.2 Gy 0.6 Gy 113 cm2 41 cm2 Lecture 9.1: Examples of good and bad practice

  28. Areas in red are saturated in the slow film. Skin dose more than 1.2 Gy. Lecture 9.1: Examples of good and bad practice

  29. No wedge filter used. Geometry with big radiation field size. Overlapping of radiation fields could occur.

  30. Lecture 9.1: Examples of good and bad practice

  31. 319 cm2 234 cm2 91 cm2 Lecture 9.1: Examples of good and bad practice

  32. Areas in red are saturated in the slow film. Skin dose more than 1.2 Gy. Lecture 9.1: Examples of good and bad practice

  33. Patients who had multiple coronary angiographies and who underwent more than four PTCAs. 7824 PTCAs performed during 14 years was analysed. • 14 patients were included in the study. Each patient had undergone between 4 and 14 coronary angiographies and between 5 and 10 PTCAs, performed over a period of 2-10 years. Lecture 9.1: Examples of good and bad practice

  34. Mean values of maximum skin dose per procedure were 217 mGy for the diagnostic studies and 391 mGy for the PTCAs. • Only a slight radiation skin injury was clinically demonstrated in one patient with a history of 10 coronary angiographies and 10 PTCAs (estimated maximum skin dose 9.5 Gy). Lecture 9.1: Examples of good and bad practice

  35. CONCLUSION: • IC procedures performed on modern X-ray systems under QA programmes and by cardiologists trained in RP, repetition of procedures is not the main cause of possible skin radiation injuries. Lecture 9.1: Examples of good and bad practice

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