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

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

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.

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

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

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

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

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

Useful Terminology

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.

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.

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

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

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

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

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.

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

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

TIME

Distance

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

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

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

SHIELDING !

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

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

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

Patient Dose Dose preparation Dose administration Post-dose measurements

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

Sign, sign, everywhere a sign…

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