A comparative physical evaluation of four X-ray films

In this study, four general purpose radiographic films (Agfa Gevaert Curix RP-1, duPont Cronex 4, Fuji RX, and Kodak XRP-1) were compared using three independent techniques. By examining the characteristic curves for the four films, film speed and contrast were compared over the diagnostically useful density range. These curves were generated using three methods: (1) irradiation of a standard film cassette lined with high-speed screens, covered by a twelve-step aluminum wedge; (2) direct exposure of film strips to an electro-luminescent sensitometer; and (3) direct irradiation of a standard film cassette lined with high-speed screens. The latter technique provided quantitative values for film speed and relative contrast. All three techniques provided virtually properly identical results and indicate that under properly controlled conditions simplified methods of film testing can give results equivalent to those obtained by more sophisticated techniques.     

The determination of the point of time in processing archived X-ray films

The point of time, in which archived X-ray films were processed, can be proved with the determination of the remaining content of thiosulphate.The methylene blue method of DIN 19069 (equivalent to ISO 18917) was adapted to X-ray films.The range of time is in about two and a half year,in which the remaining content of thiosulphate is correlatable to the point of time in processing. This range of time covers the range, in which "radiological bodies" control the results of constancy testing. This method brings the "radiological bodies" in a better position to decide wether the recommended time of processing is true or not, when test images according DIN 6868-3 and/or the sensitometric step wedges according DIN 6868-2 are checked.     

Sensitometric evaluation of four dental X-ray films using five processing solutions.

OBJECTIVES: To compare the sensitometric properties of four dental films: Ektaspeed Plus and Ultra-speed (Kodak Eastman Co, Rochester, USA) and new and previous Dentus M2 (Agfa-Gevaert, Mortsel, Belgium) in five different processing solutions. METHODS: Characteristic curves were constructed for four dental X-ray films using five different processing solutions. All films were processed manually in three sets of chemicals for manual processing: Agfa (Heraeus Kulzer, Dormagen, Germany), Kodak (Kodak-Pathé, Paris, France) and Demat (Viscopac, Athens, Greece) and two sets of chemicals for automatic processing: Dürr XR and Periomat (Dürr Dental, Bietigheim-Bissingen, Germany). Analysis of variance and regression analysis was performed to examine the factors significantly affecting film density. RESULTS: The new Dentus M2 film had comparable gradient, higher speed and lower base-plus-fog than its predecessor. It had comparable speed with Ektaspeed Plus in chemicals for automatic processing. All films had a higher speed and lower gradient when processed in the chemicals for automatic processing. The highest film speed was achieved using Dürr XR chemicals. CONCLUSIONS: The new Agfa Dentus M2 film is an E-speed film and can be considered an alternative to Ektaspeed Plus: both can be recommended for use in dental practice as they contribute to dose reduction.     

数字化摄影诊断腺样体肥大的价值(附86例分析)

目的:探讨鼻咽部侧位片对小儿腺样体肥大的诊断价值。方法:86例怀疑腺样体肥大患儿均摄鼻咽部侧位片,测量腺样体厚度、鼻咽腔宽度及后气道宽度(PAS),并计算腺样体指数A/N,以评估腺样体肥大程度。结果:A/N≤0.60者16例,0.61～0.70者14例,A/N≥0.71者56例;PAS≤5mm者36例;6～10mm者24例;≥10mm者26例。结论:X线鼻咽侧位片是诊断腺样体肥大简单、经济的一种重要检查方法。     

Independence of calibration curves for EBT Gafchromic films of the size of high-energy X-ray fields.

The EBT Gafchromic radiochromic film is a relatively new product designed specifically for dosimetry in radiation therapy. Due to the weak dependence of its response on the photon energy (variations are below 10% in the 50 kVp-10 MVp range), the film is ideal for dosimetry when the photon energy spectrum may be changing or unknown. In order to convert a map of optical densities into a map of absorbed radiation doses, a calibration curve constructed on the basis of standard calibration films is necessary. Our results have shown that, with the EBT Gafchromic film, one can use the same calibration curve for 6-MV X-ray fields of any size in the range from 5 x 5 cm(2) up to 40 x 40 cm(2). This is not the case for radiographic films, such as Kodak X-Omat V, whose response to the same dose varies approximately by 10% depending on the field size in this range. This insensitivity of the EBT Gafchromic film to size of the radiation field makes it possible to assess doses delivered by small radiation fields. With the help of this film, it was shown that the output factor for a 0.5 x 0.5 cm(2) field is 0.60+/-0.03 (2SD) relative to the 10 x 10 cm(2) field.     

Influence of scattered radiation and tube potential on radiographic contrast: comparison of two different dental X-ray films.

The fundamental concept in image quality of contrast has been analysed in terms of its elements; film, radiation and object contrast, and the theoretical formula to describe their interrelationship have been evaluated. Experiments were designed to investigate the dependence of radiographic contrast on the kV, the type of generator and dental film used (D and E speed). An ivory wedge was used as the object, both alone and within a polymethyl methacrylate phantom as scattering medium. Precise definition and control of the X-ray generators were achieved by means of measurements of the primary X-ray spectra using a Compton spectrometer. D speed was found to have higher film contrast than E speed when compared at the same optical density, due to its lower base and fog and lower level of saturation in these experiments. On the other hand, E speed was found to have wider latitude. The experimental object was reproduced with the highest radiographic contrast using D-speed film and, with a given type of generator, this increased when the kV was decreased. While no difference in scatter/primary ratios was observed using the two different films, a weak dependence on kV in the range from 36 to 77 kV was found and confirmed by Monte Carlo calculations. The results indicate that the D and E speed films used had equal energy absorption properties; the difference in radiographic performance is due to their different film characteristics. The importance of controlling the physical parameters (photon energy spectrum, base and fog and optical density level) when comparing image qualities is clearly demonstrated.     

食管壁内气管异位的X线临床表现与病理分析(附3例分析)

目的：分析食管壁内气管异位的临床表现，X线特征与病理学之间的关系。揭示影像学的病理基础。提高影像学诊断的准确性。方法：3例病人均经X线检查及手术，病理证实。结果：X线仅诊断为先天性食管良性狭窄，病理诊断为食管壁内气管异位，结论：食管壁内气管异位是气管梗阻的原因之一。其临床表现及X线征象与病理学分型密切相关。