Characterization of a digital radiography system EN/MME/MM departement Characterization of a digital radiography system Marine Torrollion Tutor: J-M DALIN DUT Physics measures internship to 04/04/11 from 17/06/11

Summary 1. The radiographic non-destructive tests at CERN 1.1. The radiography laboratory 1.2. The material used 2. Description of the digital radiography system 2.1. Steps of the radiography acquisition 2.2. List of the parameters 2.3. Quality of the picture 3. System characterization 3.1. Study of the X-Ray beam 3.2. Creation of control graphics Conclusion

1. The radiographic non destructive tests at CERN Photography of the radiography lab

1.1. The radiography laboratory A control area : the bunker Its role at CERN Radiography instruments are stored in a closed room with concrete and lead walls and roof: two X-ray tubes the X-ray tomograph Perform the control of metallic pieces Material defects, scattered porosity, cracks… Accept or reject with respect to reference quality levels Photography of the big door of the bunker Examples of weld defects

1.2. Materials used Ordinary films Phosphor plates Silver films single use, price : €8.30 each non linear response have to be developed with a complex and heavy process which needs chemical products Cover of phosphor crystals can be used 1000 times, possibility to delete the picture in memory, price : €300/unit linear response can be read directly with a scanner, easy to stock and to be network accessible - are easier to recycle Phosphor plates Silver films

2. System description Scanner Scanner DURR Computer X-ray Tube Phillips Phosphor plates

2.1. Steps for the radiography acquisition Picture capturing Reading with the scanner Connection with a USB cable Deletion of the picture in memory Phosphorus plate can be used again Transmission of the informations to the computer Acquisition of the radio by the software D-Tect Modification and storage of the radio

2.2. List of the parameters ADJUSTABLE PARAMETERS I x Potential difference ddp ADJUSTABLE PARAMETERS I x X-Ray tube Anode * F : distance piece- source x cathode * b : distance piece - plate Collimator * T : Time of exposure T F * ddp : potential difference * I : size of the source FIX PARAMETRERS e Piece containing weld * e : piece thickness b Phosphor plate * µ : linear coefficient of attenuation (cm-1) Plate in lead

2.3. Quality of the picture Resolution Homogeneity of the radiations 1 mm Resolution IQIs classicals Target with convergent lines Homogeneity of the radiations Homogenous plate of aluminum X-ray Linearity of the absorption Low intensity High intensity Graduates wedges

3. System characterization

3.1. Study of the X-ray beam Objective : To measure the influence of the piece-source distance on the beam diameter and the radiation intensity. Evolution of the beam diameter Radiation intensity of the beam

The influence of the piece-source distance on the beam diameter Incertitudes of repetability = corrected standard deviation of the measures Function is a straight line: diameter = f(f) The diameter grows proportionally with the piece-source distance Possibility to check the angle of irradiation with trigonometric calculations

Comparison of slopes for irradiations angles of 35 and 40 degrees The three experimental measures are on the theoretical straight line of α = 40° The provider announces an irradiation angle of 35° The outline of the beam is blur

3.1. Study of the X-ray beam Objective : Measure the influence of the piece-source distance on the beam diameter and the radiation intensity. Evolution of the beam diameter Radiation intensity of the beam

Intensity reading on the beam diameter Homogeneous radiations on the beam center Perturbations of the measures by an important noise The intensity decreases progressively from the center to the periphery of the beam

Intensity handreading on beam’s diameters Radiation distribution is similar in the three cases Only the intensity changes with the piece-source distance 40 % of the beam is homogeneous

3.2. Creation of control graphics Objective : To allow the operator to achieve a good result at the first manipulation and gain time Radiography series N° radio T (s) ddp (kV) f (mm) pictures 1 45 60 450 2 70 3 4 600

Example of a graphic obtained with a copper wedge , f = 450 mm :

Final presentation of the controls graphic Controls graphic for copper piece and a piece-source distance of 450 mm at 10 mA

Conclusion Scientific assessment: This work allowed me to check the distribution of the beam radiation, and to create the control graphics for a source of 10 mA The control graphics allow the operators to obtain a good radiography at a first manipulation. Follow-up actions: The creation of control graphics for 4 mA source and a study of the image quality (resolution, contrast, brightness, ...).

Thanks Many thanks to Jean-Michel Dalin, my tutor, for his attention and his explanations, As well as to Mr. Sgobba, in charge of the section EN/MME/MM. Thanks to Aline Piguiet for her assistance during the manipulations. And finally, a huge thanks to all the section members.

End of the presentation Thanks for your attention, Any questions ?