A tomographic imaging plane, perpendicular to the ground, the coronal plane separates the anterior from the posterior part (the front from the back).

If available, some graphic aids can be helpful to show image orientations.
1) A graphic icon of the labeled primary axes (A, L, H) with relative lengths given by direction sines and system of coordinates as if viewed from the normal to the image plane can help orient the viewer, both to identify image plane orientation and to indicate possible in plane rotation.
2) In graphic prescription of obliques from other images, a sample original image with an overlaid line or set of lines indicating the intersection of the original and oblique image planes can help orient the viewer. The location in the R/L and P/A directions can be specified relative to the axis of the scanner.
The F/H location can be specified relative to a convenient patient structure.
The orientation of single oblique slices can be specified by rotating a slice in one of the basic orientations toward one of the other two basic orthogonal planes about an axis defined by the intersection of the 2 planes.
Double oblique slices can be specified as the result of tipping a single oblique plane toward the remaining basic orientation plane, about an axis defined by the intersection of the oblique plane and the remaining basic plane. In double oblique angulations, the first rotation is chosen about the vertical image axis and the second about the (new) horizontal axis. Angles are chosen to have magnitudes less than 90° (for single oblique slices less than 45°); the sign of the angle is taken to be positive when the rotation brings positive axes closer together.

A bitewing radiograph is an intraoral device that demonstrates the crowns, necks and coronal thirds of the roots of both upper and lower teeth. The imaged person bites upon a tab or wing projecting from the center of the image-receptor packet.

See also Bisecting Angle Technique.

(CT or CAT scan) Computed tomography is a diagnostic imaging technique, previously also known as computerized axial tomography (CAT), computer-assisted tomography (CAT), computerized tomographic imaging, and reconstructive tomography (RT).
A CT scan is based on the measurement of the amount of energy that a tissue absorbs as a beam of radiation passes through it from a source to a detector. As the patient table moves through the CT scanner, the CT tube rotates within the circular opening and the set of x-ray detectors rotate in synchrony. The narrow, fan-shaped x-ray beam has widths ranging from 1 to 20 mm. The large number of accurate measurements with precisely controlled geometry is transformed by mathematical procedures to image data. Corresponding to CT slices of a certain thickness, a series of two-dimensional cross-sectional images is created.
A CT is acquired in the axial plane, while coronal and sagittal images can be rendered by computer reconstruction. Although a conventional radiography provides higher resolution for bone x-rays, CT can generate much more detailed images of the soft tissues. Contrast agents are often used for enhanced delineation of anatomy and allow additional 3D reconstructions of arteries and veins.
CT scans use a relatively high amount of ionizing radiation compared to conventional x-ray imaging procedures. Due to widespread use of CT imaging in medicine, the exposure to radiation from CT scans is an important issue. To put this into perspective, the FDA considers the risk of absorbed x-rays from CT scans to be very small. Even so, the FDA recommends avoiding unnecessary exposure to radiation during diagnostic imaging procedures, especially for children.
CT is also used in other than medical fields, such as nondestructive testing of materials including rock, bone, ceramic, metal and soft tissue.

See also Contrast Enhanced Computed Tomography.

Tomography is imaging by sections or sectioning to obtain images of slices through objects like the human body. Tomography is derived from the Greek words 'to cut or section' (tomos) and 'to write' (graphein). A device used in tomography is called a tomograph, while the image produced is a tomogram.
The first medical applications utilized x-rays for images of tissues based on their x-ray attenuation coefficient. The mathematical basis for tomographic imaging was laid down by Johann Radon. This type of imaging is used in different medical applications as for example computed tomography, ultrasound imaging, positron emission tomography and magnetic resonance imaging (MRI) also called magnetic resonance tomography (MRT).
Conventional x-ray tomographic techniques show organ structures lying in a predetermined plane (the focal plane), while blurring the tissue structures in planes above and below by linear or complex geometrical motion of the x-ray tube and film cassette.
Basically, computed tomography is the reconstruction of an image from its projections. In the strict sense of the word, a projection at a given angle is the integral of the image in the direction specified by that angle. The CT images (slices) are created in the axial plane, while coronal and sagittal images can be rendered by computer reconstruction.

See also Zonography, Computed or Computerized Axial Tomography, Resolution Element, Radiographic Noise, Intravenous Pyelogram.