Читать книгу Leksell Radiosurgery - Группа авторов - Страница 88

To measure radiation profiles, we require two pieces of equipment: film and a scanner to process these images. Special film is used for measuring radiation profiles, output factors, and the radiologic focal point. This film is called radiochromic film and one type is called Gafchromic. This film does not require a film processor. Gafchromic EBT3 (Ashland, Covington, KY, USA) is the latest version and has many features [3–11] that make this film suitable for Gamma Knife dosimetry. The profiles are measured in either an ABS (acrylonitrile butadiene styrene) phantom, this is the original phantom developed for the Gamma Knife, or solid water phantom by aligning the film in the x:y and x:z orientation. From the Elekta report, their measured values and the values that are in the treatment planning software can be compared to the users. The profile values are determined from the 50% isodose line. The physicist should verify that the profiles are within 1 mm of the expected.