14.3 Radionuclide Therapy Procedures
Key Takeaways
- Therapeutic administrations require a written directive, identity verification, activity assay, and documentation under the authorized user—technologists execute the radiation-safety and patient-care workflow
- I-131 sodium iodide is used for hyperthyroidism and thyroid remnant/ablation pathways with isolation, contamination control, and NRC-style release criteria education
- Lu-177 Dotatate (NET) and Lu-177 PSMA (prostate) are peptide receptor / ligand therapies with infusion protocols, antiemetic/amino-acid regimens as ordered, and post-therapy imaging when indicated
- Ra-223 dichloride and Sr-89 treat bone metastases (alpha vs beta teaching); Y-90 microspheres are device/IR-coordinated hepatic radioembolization
- Surveys, inpatient vs outpatient decisions, waste, room release, and patient instructions are as testable as the isotope name
14.3 Radionuclide Therapy Procedures
Quick Answer: Therapy day = written directive + right patient/right RP/right activity + safety controls + surveys/waste/release education. Know I-131, Lu-177 Dotatate/PSMA, Ra-223, Sr-89, and Y-90 microspheres as workflows, not just brand names.
Domain II and V merge here: you are not the authorized user who independently selects therapy activity, but you own the operational chain that keeps patients, staff, public, and license conditions safe.
Universal Therapy Workflow
| Step | Tech / team actions |
|---|---|
| 1. Written directive | Present before administration; matches patient, RP, route, activity (or formula) |
| 2. Identity & consent | Two identifiers; pregnancy status for relevant ages; consent per policy |
| 3. Assay | Dose calibrator measurement; residual syringe/vial after administration |
| 4. Administration | Route-specific technique (oral capsule/liquid, IV infusion, IR catheter) |
| 5. Immediate safety | Spill kit ready; PPE; shield; time/distance |
| 6. Surveys | Patient, area, staff as required; document mR/h at set distances |
| 7. Release / isolation | Apply regulatory release criteria or inpatient hold; teach hygiene |
| 8. Waste & records | Decay-in-storage logs, return shipping if needed, chart all measurements |
Basic dosimetry concepts (tech level): prescribed activity may come from empiric fixed amounts, weight-based activity, or pretherapy imaging (e.g., I-123/I-131 diagnostic uptake, MAA shunt fraction for Y-90). Record administered activity = assayed − residual. Post-therapy imaging (bremsstrahlung, SPECT/CT, or gamma emissions from Lu-177) verifies distribution when ordered.
I-131 Sodium Iodide (Hyperthyroid and Ablation)
| Pathway | Teaching notes |
|---|---|
| Hyperthyroidism | Outpatient oral capsule common; lower activities than remnant ablation |
| Thyroid cancer remnant / ablation / treatment | Higher activities; may require inpatient isolation depending on activity and release criteria |
Prep: low-iodine diet and TSH stimulation pathway (withdraw thyroxine or use rhTSH) are clinical orders—confirm they were followed when the requisition requires it. Stop interfering iodinated contrast/meds per timeline. Pregnancy test documentation is mandatory in applicable patients; counsel breastfeeding cessation per policy (often prolonged).
After administration: control vomit risk early (contamination); private toilet instructions; hydrate; avoid prolonged close contact with children/pregnant persons for a protocol-defined period; separate utensils/laundry teaching as applicable. Survey the patient at 1 m (or per SOP) against release criteria (NRC-style activity or dose-rate thresholds—know that release is criteria-based, not “feelings”). Inpatient rooms: map hot spots, use disposable covers, hold trash for decay, release room only after survey clearance.
Lu-177 Dotatate (e.g., Lutathera® class teaching)
Lu-177 DOTATATE delivers beta therapy to somatostatin receptor–positive NETs. Typically given as a slow IV infusion with concurrent amino acid infusion (renal protection) and antiemetics per product labeling/protocol. Multiple cycles weeks apart are common.
| Tech focus | Detail |
|---|---|
| Extravasation prevention | Secure IV; monitor infusion site |
| Contamination | Lu-177 has gamma emissions useful for imaging but still contaminates |
| Post-therapy imaging | SPECT/CT of distribution when ordered (same admission or next day) |
| Radiation precautions | Time/distance/hygiene for family; follow written patient instructions |
| Labs / clinical holds | Confirm AU cleared labs (marrow, renal) before you hang the dose |
Lu-177 PSMA Ligand Therapy
Lu-177 PSMA agents treat PSMA-avid metastatic prostate cancer under authorized protocols. Workflow resembles other IV radioligand therapies: written directive, assay, controlled infusion, contamination control, possible post-therapy SPECT, and outpatient precautions focused on urinary excretion (hydrate, frequent voiding, bathroom hygiene).
Ra-223 Dichloride and Sr-89
| Agent | Emission teaching | Clinical niche |
|---|---|---|
| Ra-223 dichloride | Alpha emitter localizing to bone mineral | Symptomatic bone mets (classic: castration-resistant prostate) |
| Sr-89 chloride | Beta bone seeker | Palliation of osteoblastic mets |
Both are IV administrations with marrow-suppression risk awareness (clinical lab review is AU/clinician domain). Alpha therapy has high LET but short range—external dose rates are typically lower than high-activity I-131, yet body fluid precautions and assay/documentation still apply. Schedule serial doses (Ra-223 often every 4 weeks × 6 teaching) and verify injection site integrity.
Y-90 Microspheres (Radioembolization)
Y-90 glass or resin microspheres are delivered intra-arterially in IR after MAA mapping. Y-90 is primarily a beta emitter (bremsstrahlung imaging possible). Tech/NMT roles vary by site: assay of vial activity, documentation of delivered vs residual, radiation safety coverage in IR, post-procedure surveys of room/staff/waste, and patient release instructions. Nontarget delivery (GI ulceration risk) is prevented by IR technique—not by planar “hoping.” Coordinate with the planning MAA study results (shunt fraction).
Inpatient vs Outpatient, Waste, and Education
| Decision driver | Examples |
|---|---|
| Activity & isotope | High I-131 more often triggers hold vs low hyperthyroid dose outpatient |
| Release criteria | Dose rate / retained activity thresholds + ability to follow instructions |
| Clinical condition | Incontinence, vomiting, inability to self-isolate → favor inpatient controls |
Waste: segregate radioactive trash, label with date/isotope, decay-in-storage until background, survey before conventional disposal. Never send hot linen through normal laundry without clearance. Documentation wins inspections: directive, assay, residual, surveys, release teaching, and lot numbers.
Post-Therapy Imaging and “Did It Go Where Intended?”
| Therapy | Common verification |
|---|---|
| I-131 | Whole-body post-therapy scan days later |
| Lu-177 agents | SPECT/CT using Lu-177 photons |
| Y-90 | Bremsstrahlung SPECT or PET (internal pair production) per capability |
| Ra-223 | Limited external imaging utility—clinical/follow-up labs dominate |
Bottom line for CNMT: treat therapy as a regulated procedure sequence. Name the agent class, route, major safety control, and release/education point—that is the exam-level skill set.
Before administering a therapeutic radiopharmaceutical, which document must be completed and match the patient, agent, route, and activity (or activity formula)?
Compared with Sr-89 chloride, Ra-223 dichloride is best distinguished for exam purposes by which emission characteristic?
After high-activity I-131 therapy, which technologist action best aligns with regulatory release practice?