To Err Is Human: Part 6 - Mitigating Potential Confusion When Communicating Paired Sets for Nuclear Medicine Prescription Orders

Triad Isotopes, Inc. presents the Part 6 installment of Dr. Laura Bauman’s To Err Is Human, a blog series focused on common errors in nuclear medicine that may occur during the process of writing, ordering and/or dispensing prescriptions. This series also emphasizes the critical importance for organizations to establish error prevention strategies.

This installment discusses the importance of including all the information about each individual dose when communicating paired sets.

Peanut butter and jelly. Batman and Robin. Rock n’ Roll. Many great things come in pairs, including doses of radiopharmaceuticals in nuclear medicine. In a sleepy hurry as usually demanded in this time sensitive and 'round-the-clock field, we may think of and, thus, discuss these pairs of doses as a single unit or a "set." Without clarification and documentation of the individual doses intended, confusion, mistakes and waste can occur.

When studying the lung, doses can be paired to evaluate functional differences in ventilation (V) and perfusion (Q), detecting anomalies like pulmonary embolisms. The injected particles of Tc99m macro aggregated albumin (MAA) lodge in the lung capillaries to display the blood flow (perfusion) of the lung. Aerosolized Tc99m pentetate (DTPA) or Xe-133 Gas can be inhaled to demonstrate airflow (ventilation) in the lungs.1

When studying the heart, doses can be paired to visualize differences in perfusion under different conditions. One dose can display the blood flow when the heart is at rest. Another dose can confirm the blood flow to the heart when it is stressed and pumping as hard as it can. If the heart shows less perfusion when it is stressed as compared to rest, it may not be getting enough blood and thus oxygen to satisfy its needs at that time. Thallium-201, Tc99m sestamibi, or Tc99m tetrofosmin can be paired with themselves or with each other because they all accumulate in the heart muscle proportional to blood flow.1

While heart and lung scans are the most common paired doses, other doses can be paired too. Brain scans can be paired to detect seizure origination by comparing ictal and interictal scans. Scans of labeled white blood cells can be paired with bone or bone marrow scans to determine more than just location but also which type of tissue is infected. MAA can be used before SIR Spheres® to ensure proper localization. Filtered sulfur colloid is often administered in sets of two or four doses to inject multiple sites for lymphoscintigraphy. A pair of I-123 capsules may be required to reach the total activity intended or to act as a standard.1

Establishing Protocols for Communicating Pairs

Although we may be tempted to save time by communicating multiple doses that are often paired as a single set unit, specifying each dose individually prevents misinterpretation. For example an order left on an overnight voicemail, "I'd like another set at 11 and 12," could be interpreted as either a heart set or a lung set and leaves even more questions. If it is a heart set, which agents should be used? If it is a lung set, which agent is used first? What activities are to be used? Instead, we could say "I'd like another heart set, that's 10mCi of sestamibi for a rest at 11:00 and 30mCi of sestamibi for a stress at 12:00 on Friday June 10." As you can see, this complete order contains the name of the radiopharmaceutical, the procedure, the activity, the calibration time and date for each individual dose.

Another example could be "I'd like another set of sulfur colloid at 9." For lymphoscintigraphy or liquid and solid gastric emptying or hepatobiliary imaging? Filtered or unfiltered sulfur colloid? What activity in each syringe? How many total syringes? Any specific volume or syringe type? A more complete order would be, "I'd like another lymphoscintigraphy set, that's four 1cc syringes each containing two hundred and fifty microcuries of 0.1um filtered sulfur colloid in 0.5 mL volume calibrated at 9 a.m. on Friday, June 10." This order contains all the specifics needed to fill this set of prescriptions.

Mindful communication between technologists and pharmacists will include all information about each individual dose in a set:

What procedure?

What product?

What activity?

What time?

What day?

What patient name (if available)?

Any specifications on volume or syringe size?


1. Gopal B Saha, Fundamentals of Nuclear Pharmacy, Sixth edition. 2010.