1. Presented at VCUHS by Jennifer Love and Mark Crosthwaite
PET/CT Workshop
Presented at VCUHS
by Jennifer Love and Mark Crosthwaite

2. Radiation Safety and Quality Control
Presented by Jennifer S. Love, CNMT, NCT

3. Radiation Safety and Quality Control Objectives
Apply and calculate exposure rate using time, distance and shielding in the PET arena.
Integrate ALARA and MPD concepts in the molecular imaging department.

4. Objectives
Compare and describe: well counter, dose calibrator, and survey meter.
Apply and evaluate CT and PET quality control procedures

5. A L A R A As Low As Reasonably Achievable time…distance…shielding

6. Back to Basics Radiation Units
Roentgen: a unit for measuring the amount of gammma or x-rays in air
Rad: a unit for measuring absorbed energy from radiation
Rem: a unit for measuring biological damage from radiation

7. Radiation Units SI Unit Special Unit Conversion Gray Rad 1Gy = 100 Rad
Sievert
Rem
1Sv = 100 rem
Becquerel
Curie
1Ci = 3.7x1010

8. Radiation Units 1 rem = 1000 mrem 1 Curie = 1000 mCi 1 mCi = 37 MBq
1 Ci = 3.7x1010 dps = 3.7x1010Bq = 2.22x1012 dpm

9. Useful Terminology

10. External Radiation Dose
Gamma, beta, or neutron radiation emitted by radioactive material OUTSIDE the body, exposing the skin, lens of the eye, extremities, and the whole body.

11. Internal Radiation Dose
Alpha, beta, or gamma radiation emitted by radioactive material INSIDE the body, exposing internal organs such as: thyroid, lung, bone, and GI system.

12. Total Effective Dose Equivalent TEDE
The sum of the effective dose equivalent (for external exposures) and the committed effective dose equivalent (for internal exposures).

13. Shallow Dose Equivalent SDE
Applies to the external exposure of the skin of the whole body or the skin of an extremity, is taken as the dose equivalent at a tissue depth of 0.007cm

14. Lens Dose Equivalent LDE
Applies to the external exposure of the lens of the eye and is taken as the dose equivalent at a tissue depth of 0.3cm

15. Deep Dose Equivalent DDE
Applies to external whole body exposure, is the dose equivalent at a tissue depth of 1cm

16. Whole body or Extremity?
Whole body for purposes of external exposure = head, trunk (including male gonads), arms above the elbow, or legs above the knee.
Extremity = hand, elbow, arm below the elbow, foot, knee, or leg below the knee.

17. NRC Occupational Dose Limits
Whole Body (TEDE)
5000 mrem/yr
Any Organ (TODE)
50,000 mrem/yr
Skin (SDE)
Extremity (SDE)
Lens of Eye (LDE)
15,000 mrem/yr
Embryo/Fetus of DPW
500 mrem/yr
Member of public
100 mrem/yr

18. A L A R A As Low As Reasonably Achievable time…distance…shielding

19. TIME

20. Distance

21. Inverse Square Law
I (D)2 = i (d)2

22. I (D)2 = i (d)2 I = original amount of radiation D = original distance
i = new intensity
d = new distance

23. Example…
At 1 meter, Ted the Technologist reads that the activity level from a source is 40 mR/hr. What is the activity reading at 2 meters away from the source?
I = 40 mR/hr D = 1m i = ? d = 2m
40mR/hr (1m)2 = i (2m)2
40mR/hr = i (4)
i = 10mR/hr

24. SHIELDING !

25. Half Value Layer
Thickness of the attenuator; for each HVL, the radiation is reduced by 50% exponentially.

26. Example…
100mR/hr – (1HVL) = 50mR/hr – (1HVL) = 25mR/hr – (1HVL) = 12.5mR/hr

27. Department Layout Control room Hot lab Patient prep room Waiting room
Scan room

28. Patient Dose Dose preparation Dose administration
Post-dose measurements

29. Radioactive Materials
Package receipt
Storage of radioactive materials
Disposal of radioactive materials
- decay in storage

30. Sign, sign, everywhere a sign…

31. Posting Requirements Radiation Area High Radiation Area
Very High Radiation Area
Airborne Radioactivity Area
Radioactive Materials