11 Rules for Using the Lead Marker
1. Left or right markers must always be used in all films.
2. Markers should be placed on the cassette where they will be clearly seen on the radiograph but not obscuring the required anatomy.
a. Markers should not be placed over the patient’s identification plocker.
b. Markers should be placed within the collimated film.
c. Markers should be placed away from the area where lead shielding on the px or the table may obscure the markers.
3. Markers should be placed appropriately to identify the px’s right or left side.
4. When the extremities and heart or shoulder girdles are being radiographed, markers should be placed on the lateral side of the body part.
5. When one film is being used for two projections of the same body parts, only one of the projections must be marked.
6. If bilateral projections are positioned in one film both left and right markers should be used to identify the corresponding sides.
7. Auxiliary markers should be used whenever possible and positioned away from the critical anatomy.
8. When lateral decubitus projections are performed, a marker indicating the side-up should be place on the upside of the cassette away from any anatomy of interest.
9. For lateral projection, a marker indicating the side closest to the film should be used.
10. When the spine is being radiograph in the lateral position, markers should be placed on the cassette anterior to the spine to be clearly visualized.
11. When the chest, abdomen or spine is being radiograph in an oblique position, the side nearest the film is generally marked. So when both sides are on the film, either marker can be used.
NOTE: The marker may also be used to identify the anatomical structures seen on the projection.
Pediatric Patients
Pediatric PX’s can be divided into several groups according to age.
1. Neonates-from birth to four weeks or one month.
2. Infants-from four weeks to twelve months.
3. Toddlers-from twelve months to three years old.
4. Pre-school-from three years to six years old.
5. School Age-from six years to twelve years old.
6. Adolescence-from thirteen years old to seventeen years old.
Geriatric Patients
• Px is erect – diaphragm lies in oblique position or plane in a level with the sixth costal cartilage anteriorly
• Px is Supine – diaphragm two to four inches higher
• Px is prone – diaphragm two to four inches lower.
Table Top
Recommended distance from the source to px is not less than twelve inches.
CR or central Ray – referred to as a principal or central beam of rays.
Four instances where CR is angled
1. When it is necessary to avoid the superimposition of overlying or underlying structures.
2. When it is necessary to avoid stacking in curve structure on itself.
Example: sacrum and coccyx
3. *When it is necessary to project through angled joints such as the knee joints and the lumbosacral joints.
4. When it is necessary to project through angled structures without foreshortening or elongation such as lateral projection of the neck of the femur.
5. Accurate Positioning and Accurate Centering – important to radiographic exposure.
