{'fraction_non_alphanumeric': 0.017632241813602016, 'fraction_numerical': 0.0, 'mean_word_length': 5.737288135593221, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
[Artefacts in ultrasonic diagnosis].

The most important artefacts are demonstrated. Artefacts resulting from the physical properties of ultrasound such as velocity errors refraction, shadowing from air and calcification, lateral shadowing behind cysts and acustic mirror image are unavoidable and represent a major limitation of diagnostic ultrasound. Mechanical calibration and adjustment must be checked regularly and corrected as necessary. Artefacts due to inadequate contact between transducer and skin, poor adjustment of depth compensation (TGC) and uneven movement of the transducer are rare in the hand of an experienced investigator. Artefacts resulting from slice-thickness and axial as well as nonaxial multiple reflection can be eliminated by changing the angle of the transducer.