Radiologic imaging studies are non-invasive and rarely harmful to the patient (from reactions to injected contrast material). There are a variety of imaging techniques. The technique used depends upon the nature of the disease to be screened, the location of the potential lesion in the body, and the availability of imaging equipment. Radiologic imaging is typically not used just for screening in the absence of history or other findings that suggest the possibility of a neoplasm, since it would be costly and time-consuming.

Plain films (standard radiographs) are easy to perform but relatively insensitive for small lesions. A chest radiograph can be used to look for lung cancer, but a cancer that appears on a chest radiograph is likely to be several centimeters in size. Radiographs of the extremities can be used to look for bone tumors. Mammography is the use of x-rays applied to breast imaging.

Computed tomography (CT) scans utilize x-rays, but produce more detailed images in axial (transverse section). They are quick to perform. CT is useful to screen for lesions of the chest, abdomen, and pelvis. It is not a sensitive technique for brain tumors.

Magnetic resonance imaging (MRI) scans provide more resolution than CT, but can be hampered by movement, since the scan is made over minutes. MRI provides excellent views of the brain.

Nuclear medicine (radionucleide) scanning is possible because an injected isotope is more selectively taken up or concentrated in a particularly body part, such as radioactive iodine taken up in the thyroid. The pattern of uptake can suggest the presence of a neoplasm.

Ultrasonography uses sound waves to produce a pattern of echos that indicate the pattern of tissues and organs. Ultrasound is good at finding cystic lesions (which are echogenic) and helping to distinguish a cystic lesion (often benign) from a solid lesion that forms a mass.

Positron emission tomography (PET) scans take advantage of differences in metabolism between normal cells and neoplastic cells. PET scans are useful in selected circumstances, such as looking for lesions of the head and neck region, but they are not good at exact localization, and they are quite expensive.

Radiologic imaging, such as CT and ultrasound, can be helpful in directing cytologic or biopsy procedures to obtain cells or tissues for pathologic diagnosis.

Once a cancer diagnosis is established, the CT or MRI scan aids in establishing the stage of the lesion to determine further therapy.