Estimation of the effective focal spot sizes in medical diagnostic X-ray tube assemblies

For evaluation of the effective focal spot sizes (EFSS), a method suggested by the EN 60336:2005 standard (standard) could be used. In this study we checked whether it is possible to make some deviations from the requirements of the standard without a significant effect on the result. An image receptor with one intensifying screen or two intensifying screens may be used, but the optical value of the slit image shall be in the range of 1.0÷1.4 and the X-ray tube power shall be ranged of about 30%÷50% of the nominal anode input power. A precision scaled magnifier (magnification of 5÷10x and scale of 0.1 mm) may be used for the slit radiogram width measurement instead of a time-consuming scanning of the slit radiogram. These deviations from the requirements of the EN 60336:2005 standard allows to shorten measurement time and to decrease tube current value during X-ray exposures, which reduces the risk of the Xray tube damage.

Kajian Sistem Radiografi Digital sebagai Pengganti Sistem Computed Radiography yang Mahal (Halaman 40 s.d. 43)

Sisitem radiografi diagnostic yang ada pada bagian radiologi Rumah Sakit Daerah (RSD) atau Puskesmas di Indonesia umumnya masih menggunakan system Radiografi Konvensional (RK) dengan film radiograf sebagai media penangkap citra. Berbeda dengan system Computed Radiography (CR) tanpa film (filmless) yang sudah ada di RS tipe A atau RS maju di kota-kota besar. Dalam studi sebelumnya telah dilakukan pencitraan system radiografi digital diagnostic berbasis X-Ray Intensifying Screen, diperoleh file radiograf digital dengan resolusi rendah, sehingga kalau dibesarkan citra radiograf menjadi pecah. Pada studi kali ini telah dikaji kemungkinan penggunaan kamera digital jenis single lens reflex pada ruang kedap cahaya. Hasil eksperimen diperoleh hasil file radiograf digital dengan resoluasi lebih tinggi dibanding sebelumnya. Kajian ini bisa dikembangkan menjadi system radiografi digital dengan memodifikasi unit penangkat gambar pada sistem RK, sehingga sistem ini bisa menjembatani antara pembacaan radiograf analog menggunakan film menjadi file radiograf digital, sekaligus sebagai pengganti sistem CR yang relative mahal.

A Study on a Multiple Film Technique Utilized in Radiographic Examination for Steel Castings With Complicated Geometry

Castings on transit railcars often have complicated geometry. Varying thicknesses and limited space for shooting are difficult for radiographic testing of such castings. To reach the high-quality requirements of the density, accuracy, contrast, and sharpness of the films, a series of experiment were performed on one casting with complicated geometry to compare different results from different shooting methodologies. Films with different ISO speeds are suitable for different wall thickness while their detection ranges overlap with each other. By adopting multiple film techniques, radiographic quality is enhanced when inspecting complicated castings geometries. The utilization of lead intensifying screen contributes to improve the image quality of the radiograph, so that the absorption of different sections is equalized and the prescribed quality level and density requirements are met. Latitude of film is improved by selecting appropriate voltage. Source-to-film distance is increased in order to minimize geometric unsharpness and ensure overall uniformity. Lead foil screens are utilized as a filter in front of films to absorb scattered radiation. In addition, back scatter radiation is reduced by placing lead plates behind the cassette. Large focal spot size is adopted. Short time of exposure is preferentially selected for the purpose of reducing the active time of scattered radiation. Moreover, the selection of other associated processing parameters helps to lessen the adverse effects caused by complicated casting geometries. The results of these experiments show that the quantities of films and inspection cost can be reduced, efficiency of inspection can be improved; missing detection in complicated areas can be effectively avoided; the detection capability is increased and reliability of inspection results is ensured. In conclusion, the multiple film technique is a satisfactory methodology for radiographic testing of steel castings with complicated geometry.