1. Week Seven

2. VETT 116: Veterinary Diagnostic Imaging 1 Overview of Week 7
A technique chart provides a consistent method of choosing the proper radiograph settings without having to calculate all of the components by hand with each exposure. Taking the time to prepare a technique chart in the beginning will help to save time, money, and radiation exposure to both the patient and staff.
A technique chart is not a “one-size fits all”. Depending on the types of radiographs, film, intensifying screens, and equipment, many different types of technique charts may need to be created for the same machine. A technique chart is an essential component in obtaining a consistent diagnostic radiograph with every exposure.

3. VETT 116: Veterinary Diagnostic Imaging 1 Week 7 Objectives
Purpose, use, and benefits of the technique chart.
Explore factors that will effect the accuracy of the technique chart.
Practice techniques and skills required to develop a technique chart.

4. VETT 116: Veterinary Diagnostic Imaging 1 Week 7 Required Reading
Clinical Textbook for Veterinary Technicians, by McCurnin and Bassert, pp
Radiography in Veterinary Technology, pp

5. Week 7 assignment due date.
VETT 116: Veterinary Diagnostic Imaging 1 Important Dates and Deadlines
Week 7 assignment due date.
Week 8 – Exam 2
Please see the Student Handbook for a complete schedule with calendar due dates.

6. VETT 116: Veterinary Diagnostic Imaging 1 Week 7 Directed Learning
Part 1: Radiographic Technique Charts
Reading Assignment: Clinical Textbook for Veterinary Technicians, pp
Also View: Rad Physics for Vet Students – Chapter 5
Upon completion of the reading assignment and viewing of this section of the weekly lesson, please answer the questions at the end of this section.

7. Small Animal Radiographic Technique Charts
Purpose:
Consistent quality radiographs
Reduced number of repeat films
Reduced radiation to patient and staff
Reduced cost and time

8. Factors Affecting Technique Charts
Several factors may influence the development and accuracy of the technique chart. Some of these include:
Speed of screens
Age of screens
Speed of film
SID
Amount of beam filtration
Temperature and time of film processing
Type of grid

9. Suggested Charts Required charts may include the following:
Screen and nonscreen
Grid and nongrid
Various film-screen combinations
Species specific
Anatomy specific

10. Variable kVp Technique Chart
Step 1: Select a Patient for Test Radiograph
A) The ideal subject will be:
Cooperative adult dog (sedation may be required)
Moderate size and muscling
Average weight (about 50 lbs)
Hair coat clean with medium to short length
B) Patient in lateral recumbency, measure widest part with calipers.

11. Variable kVp Technique Chart
Step 2: Evaluate the x-ray machine.
Evaluate some of the basic constant factors:
Line voltage (does voltage to the machine remain constant?)
Source-image Distance (SID)

12. Variable kVp Technique Chart
Step 3: Exposure Technique
A) Kilvoltage
Santes’ Rule
(2 x tissue thickness in cm) + SID + grid factor = kVp
Example 1:
Thickness: 20 cm SID: 40 inches Grid: 8:1
Calculation: (2
20) + 40 + 8 =
88 kVp x

13. Variable kVp Technique Chart
Step 3: Exposure Technique
A) Kilvoltage
Example 2:
Thickness: 15 cm SID: 40 inches Grid: 12:1
Example 3:
Thickness: 9 cm SID: 40 inches Grid: None
Answers: Example 2 – 82 kVp Example 3 – 58 kVp

14. Variable kVp Technique Chart
Step 3: Exposure Technique
B) Milliamperage (mA) – select highest setting possible with least amount of exposure..
C) Exposure time – select fastest setting appropriate for mA
Which would be a faster time?
1/120
Time settings will be chosen according to specifications of intensifying screens.
1/40
1/8

15. Variable kVp Technique Chart
Step 4: Film-screen system
Select the intensifying screen that best represents an average speed
Select film that is not expired or damaged.
Step 5: Grid
Double check Grid Ratio
Ensure Grid is in place

16. Create Base Chart Step 6: Test Exposure Step 7: Evaluate Radiograph
Using calculated kVp and mAs, set the kVp, mAs, and time on the control panel of the machine. Verify mA.
Process film in standardized dark room with adequate developing and fixing solutions.
Step 7: Evaluate Radiograph
Too dark: Decrease mAs by 30% - 50% or kVp 10% - 15%
Too light: Increase mAs by 30% - 50 % or kVp 10% - 15%
Repeat Developing and Evaluation process.

17. Create Base Chart Step 8: Formulate and Plot Technique Chart
If the measure of thickness is less than 10 cm – a grid is normally not used. (this will also adjust the mAs and time)
For every cm above the base setting – increase kVp by 2.
For every cm below the base setting – decrease kVp by 2
For kVp settings greater than 80 – increase kVp by 3.

19. VETT 116: Veterinary Diagnostic Imaging 1 Week 7 Directed Learning
Part 1: Radiographic Technique Charts – Review Questions
Upon completion of the reading assignment and reviewing the weekly lesson, be able to answer the following questions.
What is Santes’ rule? How does it apply to producing a radiology and what is the formula?
2) Using Santes’ rule, calculate kVp using the following information:
Thickness of area: 11 cm
Grid factor: 12
SID = 40
What is the kVp?
Please remember a printable copy of this assignment, may be accessed by clicking on the paperclip icon that is located on the presentation toolbar below.

20. VETT 116: Veterinary Diagnostic Imaging 1 Week 7 Directed Learning
3) How is a technique chart created?
4) What factors will influence the technique chart?
5) What type of patient should be used for creating a technique chart? Describe the physical characteristics.

21. VETT 116: Veterinary Diagnostic Imaging 1 Week 7 Directed Learning
6) Any body part exceeding this measurement requires the use of a grid to reduce fog-producing scatter radiation.
20 cm
10 cm
2.5 cm
30 cm
7) If an initial radiograph is too light, how should the kVp and mAs be adjusted?
8) If an initial radiograph is too dark, how should the kVp and mAs be adjusted?

22. VETT 116: Veterinary Diagnostic Imaging 1 Week 7 Directed Learning
Part 2: Development of a Technique Chart
For this assignment, you will create a technique chart based on the given factors:
Measurement: 10 cm (Lateral abdomen)
Film Speed: Medium (5 mAs to 12.5 mAs)
Grid ratio: 8:1
SID: 40 inches
mA = 300
Your assignment is to:
Calculate the kVp, mAs, and time that should be used for the initial radiograph.
Develop your technique chart for measurements of 5 cm through 25 cm in increments of 1 cm.

23. VETT 116: Veterinary Diagnostic Imaging 1 Week 7 Directed Learning
Your technique chart should include the following information:
Thickness
(cm)
kVp mA
Time
(seconds)
mAs
SID
Grid
Submit this assignment to your course instructor by the week 7 assignment due date. (20 points)

24. Additional Resources Creating a Radiographic Technique Chart
Creating Your Technique Chart
Developing Your Own Technique Chart

25. VETT 116: Veterinary Diagnostic Imaging 1 Conclusion
This concludes Week 7 assignments for Diagnostic Imaging 1. Please make sure you have completed all reading and written assignments. You may be asked this information again through quizzes, discussion, or exams.
Please submit the following to your Course Instructor:
Week 7, Part 2 Technique Chart
Complete the Assignment Verification checklist through your WebCT course website
If you have any questions regarding any of the assignments or information presented during this week, please contact your course instructor.

26. Resources
Clinical Textbook for Veterinary Technicians, McCurnin and Bassert
Radiography in Veterinary Technology, Lavin, 4th edition.
Practical Radiograph for Veterinary Nurses, Easton.