Therapeutic use of nuclear substances – Best practices

The CNSC has recently seen an increased use of novel nuclear substances for therapeutic purposes, in particular lutetium 177 (Lu-177). With Lu-177 being a relatively new nuclear substance in the medical industry, nuclear medicine licensees have been seeking guidance, specific to radiation safety measures, on its use.

Introduction

The guidance in this document is meant to help licensees implement a safe and effective radiation protection program (RPP) for any therapy administered under a therapeutic nuclear medicine licence for any nuclear substance (alpha, beta, or gamma emitters).

It is important to note that licensees remain responsible for ensuring that regulatory and licence requirements are met and that their RPP incorporates measures for minimizing exposure to others when using any nuclear substance. From a radiation protection perspective, the ALARA (as low as reasonably achievable) principle must always be applied.

As per REGDOC-1.6.1, Licence Application Guide: Nuclear Substances and Radiation Devices, policies and procedures should address the following:

• administration of nuclear medicine therapy doses
• instructions to caregivers
• instructions to patients of nuclear medicine therapy and their families
• release of patients
• assignment of nuclear medicine therapy rooms
• decontamination and reuse of treatment rooms
• medical emergencies

Best practices: Preventing radiation exposure to others (family, caregivers, health care personnel)

Given that the dose to others from exposure to a patient has the potential to exceed 1 millisievert (mSv), licensees should follow these best practices:

• Perform a dose assessment based on the patient instructions and the resulting expected patient movements and/or interactions with others to ensure that the prescribed public dose limit is not exceeded.
• Ensure that any dose constraint (typically 5 mSv) attributed to the patient’s primary caregiver is not exceeded as a result of the therapy.
• Determine the doses to the most exposed individuals, including the primary caregiver.

Note: Particular attention should be paid to the potential dose after the period of constraint, up until the nuclear substance has completely decayed away. The worst-case scenario would be someone sharing a bed with the patient (0.3 to 0.5 m apart) for 8 hours per night.

Minimizing the risk of contamination

Contamination occurs primarily during the administration itself (i.e., orally or by injection) or through contact with bodily fluids such as blood, urine and stool after administration. The following best practices can help minimize the risk of contamination:

• The injection and treatment rooms should be prepared in a way that reduces potential contamination. The preparation could include covering the floor and the bed or chair with absorbent pads and/or plastic liners.
• Personal protective equipment (PPE) must be worn at all times by anyone handling the nuclear substance and by staff administering the treatment. It is important to verify and assess any skin contamination to workers using the guidance set out in REGDOC-2.7.2, Dosimetry, Volume I: Ascertaining Occupational Dose.
• After administration is complete, the patient should be encouraged to drink lots of fluids and to void frequently, preferably in a seated position. It is recommended that the toilet be flushed 2 to 3 times or that a private bathroom be used.
• Once the patient is released, the area must be monitored for contamination. This includes the injection room, the treatment rooms and the washrooms used.
• Decontamination should be performed and the record filled out as soon as possible.

Providing relevant instructions to the patient and caregiver

The patient and their caregiver must be given clear and concise instructions on how to minimize exposure and prevent the spread of contamination. The instructions could be in the form of an information sheet or wallet card. The following information should be included in the instruction package:

• name of patient
• nuclear substance and activity administered
• treatment date and the dates of any upcoming treatments
• contact information in case of emergency or inquiry (Radiation Safety Officer)
• precautions to follow, including a timeline of how long the precautions will be in effect
• note regarding travel, as the patient may trigger portal monitors
• note regarding death and cremation

In addition, the patient and caregiver should be reminded to give the information sheet to any subsequent caregiver so that anyone involved in the care of the patient is properly informed of any required precautions. For example, the information must be shared at any other appointments or if the patient is hospitalized at another health care centre.

If the patient is hospitalized elsewhere

The CNSC believes that reaching out to other medical centres that may be involved in the care of a treated patient is a step in the right direction for preventing exposure to others, minimizing the spread of contamination, and optimizing the dose to workers and the public while providing optimum health care.

If the original treatment centre becomes aware that a patient has been hospitalized elsewhere, it should contact that health care centre to inform the other health care providers of the radioactive therapy and the instructions to follow to reduce exposure to others.

If electronic medical records (EMRs) are used in the province, brief alerts could be used to keep other caregivers informed. If EMR flagging is implemented, the person in the nuclear medicine department who will be creating the flags must be identified.

It is the licensee’s responsibility to provide instructions to reduce exposure to the people interacting with the patient and to ensure that the patient is able to understand and follow those instructions – communication is key.