خصوصیات هندسی در رادیوگرافیGeometric properties in radiography

خصوصیات هندسی در رادیوگرافیGeometric properties in radiography

اسلاید 1: Geometric properties خصوصیات هندسی

اسلاید 2: A conventional radiograph is made with a stationary x-ray source and displays a two-dimentional image of a part of the body. such images are often called plain or projection views.The principles of projection geometry describe the effect of focal spot size and relative position of the object and image receptor on image clarity ,magnification and distortion.Clinician use these principles to maximize image clarity,minimize magnification and distortion and localize objects in the image field.

اسلاید 3: Image resolution and sharpnessSharpness measures how well a boundary between two areas of differing radiodensity is reveled.Image spatial resolution measures how well a radiograph is able to reveal small objects that are close together.

اسلاید 4:

اسلاید 5: There are three means to maximize image sharpness:1.use as small an effective focal spot as practicalDental x-ray machines should have a effective focal spot of 0.4 mm because this greatly adds to image clarity.A larger angle between target and long axis of electron beam decresed heat per unit of target prolonging tube life larger effective focal spot loss of image clarity

اسلاید 6:

اسلاید 7: 2.increse the distance between the focal spot and the object by using a long open-ended cylindreA longer distance between the focal spot and the object minimize blurring by using photons whose path are almost parallel