A Radiology Portfolio: Today’s Solutions for Successful Imaging
COURSE DESCRIPTION:
Advances in technology have made a significant impact on the field of dental radiography. For
dental practices to make a smooth transition to new technology, an understanding of the basic
principles of intraoral radiography and the modifications to these principles required by new
technology is beneficial. This course provides the dental professional with techniques to utilize
with their current technology, analog or digital, to produce quality, diagnostic images on the first
exposure.
COURSE OBJECTIVES:
Upon completion of this course, the participant will be able to:
1. Compare and contrast the differences between analog and digital technique with
modifications.
2. Recognize advantages and limitations of new radiographic technology, digital
systems and new designs in aiming devices and holders.
3. Recognize technology changes and the impact of radiation exposure.
HISTORY
1895: Wilhelm Conrad Roentgen – discovered radiation
1896: Otto Walkhoff – radiation in dentistry; 25 minute exposure
1896: C Edmund Kells – 1st practical use of radiographs in dentistry.
1901: William Rollins – 1st paper on radiation dangers
BASICS and TERMINOLOGY
1. Radiation: form of energy carried by waves or streams or particles
2. X-Radiation: High energy radiation produced by the collision of a beam of electrons
with a metal target in an x-ray tube.
3. X-Ray: Beam of energy that has the power to penetrate substances and record
image shadows on a receptor (film/sensor)
4. Radiograph: Photographic/electronic image produced by the passage of x-rays
through an object.
5. Matter: Anything that occupies space and has mass
6. Atom: The most fundamental unit of matter. It is composed of nucleus (center),
protons (positive charge), neutrons (no charge) and electrons (negative charge with
binding energy).
7. Ion: Electrically unbalanced ion
8. Ionization: Converting atoms to ions
9. Ionizing Radiation: High power to overcome
10. Ion Pair: Atom with an electrical charge
11. Impulses: Length of time that radiation is produced and controls exposure time.
12. Density: Overall darkness of a radiograph affects diagnostic quality.
13. Contrast: Difference in degrees of blackness between adjacent areas.
a. High Contrast/Low kVp: Black and white = caries disease detection
b. Low Contrast/High kVp: Many shades of grey = periodontal disease detection
SOURCES OF RADIATION
1. Greatest single source of per-capita exposure: radioactive decay or radon gas from
soil.
EQUIPMENT
1. X-Ray tube: X-radiation is radiated that is produced when a beam of electrons collide
with a metal target. This conversion occurs within the tubehead of the dental x-ray
unit. X-ray tube contains the cathode (negative electrode), anode (positive electrode)
and tungsten target (metal in which the electrons strikes and turns into photons).
2. Extension arm: Suspends tubehead; after much use, can drift
3. PID: Positioning Indicating Device
4. Angulation scale: Identifies the degree of vertical angulation
5. Activating button: AKA Firing pin, exposure switch
6. Sensor: A receptor which captures the image
TYPES OF RADIATION
1. Primary Radiation: AKA Primary Beam or Central Ray which is the penetrating x-ray
beam that is produced at the target of the anode and exits the tubehead.
2. Secondary Radiation: X-radiation that is created when the primary beam interacts
with matter. It is less penetrating than primary radiation.
3. Scatter Radiation: A form of secondary radiation which results when an x-ray is
deflected from its path by interaction with matter.
TYPES OF MEDIA
1. Analog: Traditional method – film
a. F Speed
b. 97.9% Active area
2. Indirect Digital: Phosphor plate (PSP)
a. Less expensive on the front end; hidden cost of replacement plates
b. Wireless, similar to film
c. Requires 1 plate per exposure
d. No technique modifications
e. Scanner needed
f. Cannot be sterilized
g. Size: 0, 1, 2, 3, 4
3. Direct Digital: Sensors
a. CCD – Charge coupled device
i. Most common
ii. Specialized fabrication process that is costly
iii. Oldest method; developed in 1960s; found in fax machines, home
video cameras, microscopes, and telescopes
iv. Silicon chip with electronic circuit; silicon sensitive to x-radiation or
light
v. X-radiation activates electrons; produces electronic charge and latent
image produced.
vi. Stored on computer
b. CMOS/APS – Complementary metal oxide semiconductor/Active Pixel
Sensor
i. Silicon based but differs from CCD in the way that pixels are read
ii. Claims 25% better resolution
iii. Lower production cost of chip than CCD
iv. Greater durability than CCD
c. Sensors in general
i.
ii.
iii.
iv.
v.
vi.
vii.
viii.
ix.
x.
xi.
xii.
xiii.
xiv.
xv.
Instant image
Wired or wireless
Rigid and thick;
Expensive on the front end; less expensive long-term
Size 0,1, 1.5, 2
Reduces exposure 60 -90%
Enhances diagnostic image
Improves workflow
Patient education tool
No chemical processing
Easy information to transfer
Infection control difficult
Lack of industry standardization
Sensor size difficult to position
Active vs inactive area
Active Area
Inactive Area
Not drawn to scale
SAFETY
1. Patient
a. Medical, Dental and Social Histories
b. Filtration
i. Filters out non-penetrating (long) wavelengths
ii. Sheets of 0.5 mm thick aluminum
iii. Machines operating at or below 70 kVp requires 1.5 mm aluminum
iv. Machines operating above 70 kVp requires 2.5 mm aluminum
c. Collimation/PID shape
i. Restricts the size of the x-ray beam
ii. 2.75” maximum diameter
iii. Round or rectangular to match shape of PID
a. Up to 60% reduction with rectangular
d. Protective apron with thyroid collar
i. Minimizes scatter radiation
ii. Check YOUR STATE requirements and recommendations
iii. NCRP requires collars for children
iv. ADA recommends collars for all patients
v. Thyroid collars reduce exposure levels by over 30%
vi. No thyroid collar with panoramic images
e. Receptor
i. Sensor
ii. Film
iii. PSP
f. Appropriate exposure factors
i. If applicable: Adjust kVp and mAs
ii. Appropriate exposure time
g. Aiming devices
i. Parallel technique is preferred
ii. Dimensional accuracy of images is reproduced and ease of standardizing
iii. Stabilizes sensor
h. Exposure technique
i. Film handling & processing
2. Operator
a. Dosimeters to monitor exposure
b. Stand 6 ft away from source of radiation
c. Stand 90 to 135 degrees to the direct beam
3. Equipment
a. State inspection with registered service company
b. Machines maintained per manufacture’s specifications
c. Keep copies of service tickets and records
GUIDING AGENCIES, ORGANIZATIONS AND BEST PRACTICES
1. NCRP: National Council on Radiation Protection; Report 145
a. Justification – The benefit of radiation exposure outweighs any accompany risk
b. Optimization – Total exposure remains as low as reasonably achievable, with
economic and social factors taken into account
c. Dose Limitation – Limits are applied to each individual to ensure that on one is
exposed to an unacceptable high risk.
d. All three of these principles are applied to evaluation of occupational and public
exposure. The first two apply to exposure of patients. However, no dose limit is
established for diagnostic or therapeutic exposure of patients. The primary
objective is to ensure that the health benefit overrides the risk to the patient from
that exposure.
2. ADA: American Dental Association
a. Based on needs, benefits vs risk
b. Used in conjunction with dentist professional judgment.
3. ALARA: As Low As Reasonably Achievable
4. Best Practices
INFECTION CONTROL
1. Autoclavable
2. Disposable
3. Barrier protectors
4. PPEs
5. Universal Precautions
MODIFICATIONS AND EXPOSURE TECHNIQUES WITH TIPS AND TRICKS
1. Technique
a. Parallel
b. Bisecting
2. Modifications and Tips and Tricks
a. Touch what you want to take
i. Sensor is parallel with tongue
ii. Touch the tooth area with the bite block
iii. Tell the patient to SLOWLY close
iv. Roll into place and place cotton rolls
3. Kick the door open
a. Opened in the anterior, closer posterior
4. Center receptor in the center of the mouth
a. More comfortable
5. Cotton rolls
a. Patient perceives the closure is softer; more comfortable
b. Stabilizes
c. Patient doesn’t have to close as far
d. Apices are cut off – place below the bite block
e. Occlusal or incisal edge is cut off – place on top of the bite block
6. Horizontal alignment with q-tip or probe
a. Determine how the interproximal is aligned
b. If using aiming devices; slot over interproximal
SPECIAL CONSIDERATIONS
LOCALIZATION
1. SLOB rule
a. Localizes structures
b. Method: 2 images exposed at different angles
2. Right-angle technique
a. Localizes structures
b. Primarily mandible
c. Method: 2 images, One periapical and one occlusal
WEAR AND TEAR
1. Sensors
a. Do not pull on cord to remove barrier
b. Gently walk barrier by pinching the ends of the bag
c.
d.
2. PSP
a.
b.
c.
Caution patient not to bite on cord
Handle with care
Do not bend ends to make more comfortable
Easily scratched; therefore, limited life span
Handle with care
PROTECT YOUR INVESTMENT
1. Sensor
a. Soap box
b. Booties
c. Hook
2. Protective Apron
a. Wash with soap and water to clean
b. Use disinfecting wipes
c. Monthly inspection
d. Fluoroscopic examination yearly
3. Manikin
a. Store with tray to protect teeth
b. Store with cushioning and in a “home”
PANORAMIC RADIOGRAPHY
1. Basic concepts
a. Extraoral radiograph
b. Rotational
c. Provides an overall view of maxilla and mandible
d. Frankfort plane
i. Top of the ear canal to bottom of eye socket; parallel with the floor
e. Midsagittal
i. Divides patient face into right and left sides and is positioned
perpendicular to floor
COMMON PANORAMIC ERRORS
CONE BEAM IMAGING
1. 3D imaging
2. Multiplanar views
3. Reduced exposure vs CT scan
REFUSAL OF RADIOGRAPHS
1. Requires dentist to refuse treatment when a patient refuses x-rays
a. Previous radiographs can be used if recent and acceptable quality
2. No document can be signed to release a dentist of liability
a. Legally cannot consent to negligent care
3. Patient education
a. Should be informed on radiographs
4. Disclosure process must be conducted by a competent dental professional