Bushong; Chapter 13 (end) Conventional Tomography

Kidneys are divided into how many poles?

3 - upper, middle nd lower

How do you measure for other tomographic procedures?

All body parts (except kidneys), take an AP & Lateral, determine where lesion is and make first cut based on where the lesion is, posterior, anterior, midline. Still measure part/area.

Which types of tomography require specialized equipment?

All except Linear.

What do all Autotomography views have in common?

All use a breathing technique

Tomography

An examination designed to bring into focus only the anatomic structure lying in a plane of interest while blurring structures on either side of that plane.

Conventional Tomography

Becoming a thing of the past; some clinics do not use any more

What is replacing IVU?

Cat scans

Class example of Conventional Tomography

Cut bread lengthwise/slice bread lengthwise instead of regular slices.

Section thickness

Determined by the tomographic angle and the amount of movement in the tube. Larger the angel=thinner the cut; More the tube moves=thinner the cut.

Panoramic Tomography

Developed to study curved structures of the head.

X-ray

Expose whole area to make image

What is the goal when we do a tomogram?

Find body part and decide what tomogram levels to use.

Common use for conventional tomography today

IVU/IVP - IV Urography/IV Polo grams

What progression do you make your "cuts" during a tomogram?

In the center of kidney, then work your way out. (ex: start at 7, the proceed to 6 & 8, then 5 & 9 until you find kidney stone)

What happens with IVU?

Inject contrast material into patient so we can see kidneys, ureters and bladder. Checking for kidney stone.

Which type of Tomography is most common?

Linear

Types of Tomography

Linear Circular Elliptical Hypocycloidal Trispiral Figure 8

Tomographic patterns/cuts require

Long exposure times High heat units

Tomogram

Move film and tube consecutively so it blurs structures above and below and we get an objective or focal plane that is in focus.

What plane does a patient lay on during an IVU/tomographic procedure?

Patient lies at 0.

Class example of CT/Computed Tomography

Slice bread like normal; pull out of loaf and see that slice.

During IVU Procedure

Start with scout film/KUB and scout tomogram of kidneys to see if stone is more anterior/posterior.

Tomographic angle or arch

The angle of movement between the tube and the image receptor.

Objective plane

The plane that is imaged CLEARLY at the level we can change thickness of objective plane, just like thick and thin sliced bread. We can determine who thin our slice is going to be based on what we are tomograming.

Zonography

Tomography which uses a very small (less than 10*) angle. Produces a very thick cut Mainly used as survey instruments. ex: can't get Dens on C-spine, do zonogram = real thick tomographic cut, right through cervical spine so you can see if dens is sheared off essentially.

T/F Conventional Tomography, even though not used much more, they are still valuable and useful information can be obtained

True

Linear Tomography

Tube/Film moving from one side of patient (head to foot or foot to head). When we move tube, we connect tube and film so they are stuck together around a pivot point/fulcrum and this is the objective plane/area of interest

Using kidneys, (posterior 1/3 of body), how do you decide what tomogram levels to use?

Use calipers to measure patient through kidney area at angle of ribs. Measure patient and take 1/3 of number and that is where to start tomographic cuts. Should be in middle pole of kidney.

How does panoramic tomography work?

Uses a special film in which the film and tube rotate around the patient's head to produce image. Patient bites on a "bite block" to hold head still during procedure.

Autotomography

Uses movement of the body parts to blur certain areas of the body while keeping others in focus. ex: Trans-thoracic shoulder Sternum Swimmers view of C and T spine Wagging jaw

CT

Uses same principles, moves the detector and x-ray, but it circles around patient instead of just moving over the patient.

Where is panoramic tomography mostly used today?

dental offices.

Fulcrum

the imaginary pivot point about which the x-ray tube moves.

Tomographic name describes

the movement of tube and type of cut being made. X-ray tube moves over patient in these patterns.

The less tube movement you have

the thicker the slice can be.

The more tube movement you have

the thinner your slice can be.

Creating tomography by

using the movement of the tube and film to create image.