Final answer:
Out-of-field artifact in medical imaging is caused when part of the patient's body is outside of the imaging area. Proper positioning and shielding are crucial to minimize these artifacts and reduce the effective dose of radiation to the patient.
Step-by-step explanation:
The term 'out-of-field artifact' in medical imaging refers to distortions or unexpected additions in an image that occur when part of the patient's body extends beyond the boundaries of the imaging area. This might happen during radiographic procedures or in magnetic resonance imaging (MRI). If a part of the patient's anatomy is not within the selected imaging region or the imaging detectors, it can cause artifacts because the image processing algorithms assume the scanned object is homogeneous within the scanned field.
In specific medical imaging techniques such as MRI, a large magnetic field is generated by the cylindrical solenoid surrounding the patient. It is important to properly position the patient and use appropriate shielding, like a lead apron, to reduce exposure to tissues not being imaged and limit out-of-field artifacts. This also minimizes the effective dose (measured in millisieverts, mSv) of radiation that the patient is exposed to during procedures like X-rays.