Safety

As you strive each day to make a difference in the lives of your patients, you are also accepting the risks associated with handling radioactive materials. Cardinal Health is committed to supporting our customers in this important work, and is proud to provide ongoing education and products, such as the PETPig™, to promote safe and responsible practices in the fields of PET and nuclear medicine.

Important Considerations of PET Radioactivity and Shielding

• PET has a 511 keV gamma ray energy that is more than 3 times greater than the 140 keV gamma ray energy of Technetium 99m.
• Technologist exposure rates from high energy positron emitting radionuclides are nearly 6 times greater than that from lower energy radionuclides typically used in nuclear medicine.
• Due to the higher energy, 16 times more lead is required to obtain the same stopping effect for 511 keV photons as compared to 140 keV photons.
• Tungsten shielding has become the absorber of choice for positron emitting radionuclides. Tungsten provides about 1.4 times the shielding capabilities for the same thickness of lead.

The Distance Factor

The amount of radiation exposure varies with distance by the “inverse square law”. In other words, if you double your distance from the source, your exposure is reduced by a factor of four (1/4th). If you increase your distance by a factor of 3, your exposure will reduce to 1/9th, and so on.

By using the side handle the radiation exposure rate is reduced by about 75% compared to the surface exposure rate. As a result, every effort should be made to maximize distance from the syringe during unit dose handling.

In addition to the benefits of tungsten, the unique Thermos® style design of the PETPig™ reduces hand exposure during dose handling based on distance. The top handle increases distance when removing the PETPig™ from the delivery container, and the side handle increases distance when transporting the dose to and from the dose calibration area, and then to the dose administration area.

The Shielding Factor

Radiation exposure can also be reduced by maximizing shielding. The density of a material is related to its radiation stopping ability. Higher density means better stopping power and shielding. Due to a higher density, tungsten has a much higher stopping power than lead. The ability to stop or attenuate photons is described as the Half Value Layer (HVL). The HVL of a material is the thickness required to reduce the incident radiation by 50%. In the case of 511 keV, 4.1 mm of lead are required to reduce the photon flux by 50%, while only 2.9 mm of tungsten can accomplish the same degree of shielding. The tungsten PETPig™ has an optimum stopping power to mass ratio that results in the double benefit of enhancing regulatory compliance of ALARA practices while diminishing the lifting requirements of workers compared to heavier lead based shielding systems.

Important Dose Administration Considerations

Commercially available PET syringe shields may provide a false sense of protection due to the thin layer of material provided. The wall thickness of the PETPig™ is 21 mm of solid tungsten (> 7 Half Value Layers) which is significantly greater than other commercially available PET syringe shields.

The uniquely designed PETPig™ from Cardinal Health transforms into a semi-remote, thick, tungsten syringe shield for dose administration. The syringe shield rests in the PETPig™ cradle making it unnecessary to hand hold the shield during dose administration.

The difference is clear. The PETPig™ reduces hand dose exposure by more than a factor of 6 resulting in a significant reduction in occupational radiation exposure.