Lecture 5- Ablations Flashcards
Thyroid cancer
Thyroid Cancer
•Painless swelling, typically one lobe
•Typically asymptomatic,
• Sx if laryngeal nerve involvement
•Well-differentiated vs. non-differentiated
• 70-90%
• Nuclear medicine Dx, Tx, follow up
• Prognosis
• 10% reoccurrence rate
Thyroid cancer types
Thyroid Cancers
•Papillary
•Follicular
•Hurthle cell
•Medullary
•Anaplastic
Follicular thyroid cancer
•Follicular
• 10-25%
• Average age 50’s
• Spreads via blood
• Distant mets = poorer prognosis
Differentiated
Hurthle cell cancer
- rare, differentiated
-aggressive - early distant Mets
Medullary thyroid cancer
• Do not concentrate radioiodine
• Aggressive, poor therapy response
• Other endocrine lesions
• Pheochromocytomas
• May secrete thyroid hormones
- thyrocalcitonin
- undifferentiated
Anaplastic thyroid cancer
• Do not concentrate radioiodine
• Worse prognosis, 10% 3-year survival
Undifferentiated
Patient management of thyroid cancer
Patient Management
•Thyroid uptake/scans
• Functioning tissue BUT hypofunctioning compared to normal tissue
= appear cold
•FNA
• Papillary/follicular
•Thyroidectomy/lymphectomy
• Partial vs. total
•Thyroglobulin levels
• > 10 ng/mL = 85% likelihood mets
•RAI WBS
•TSH levels/stimulation
When to do a WB survey
•Pre-Ablation (4-6 wks)
• Depends on met risk
• Query residual thyroid and mets
• May not see mets even if present
•Post-Ablation
• Assess patient with higher dose post-therapy
• 10% show abnormal uptake NOT previously visible
• Alters management
•Follow Up
• 6 months post-therapy, continued + Tg levels
WB survey prep
•Elevated TSH
•Post-thyroidectomy and follow ups
• Hormone withdrawal or rTSH
•No hormone
• Do not prescribe post-thyroidectomy
• Come off meds for follow up
•rTSH (Thyrogen)
• 2 consecutive day adm.
• 0.9 mg, IM injection
• +/- TSH checked
• Third day: give RAI
•Discontinue medications
• T4: 4-6 wks
• T3: 2 wks
•Low Iodine Diet: 2 wks
• <50 ug/day
• Thyroid tissue starved
• Elevated TSH
Thyrogen (rTSH)
Indications
• Unable to elevate TSH level
• Previous thyroid hormone withdrawal caused life-threatening
complications
• Medically inappropriate to withdraw thyroid hormone
•Side effects >5%
• Headache, nausea, vomiting, weakness, allergic rx
•Very expensive
RAI WB surveys procedure I-131
•131I
• 74-185 MBq
• How does stunning affect therapy?
• 48-72 hr (or longer)
• Collimators
• Windowing
• SPECT/CT & WB with standard
• Neck to pelvis
• Star artifact
RAI WB Survey with I123
•123I
• Replacing I-131?
• Stunning a non-issue
• ++ image quality
• 6-24 hr imaging
• Collimators
• 55-111 MBq
• Standard imaging
• WB/high count spot views/SPECT-CT
Biodistribution of iodine
•Nasal, oropharynx, salivary, thyroid, GI, GU, breast
• 7 days: liver, minimal GI, GU
•False +’s
• Normal distribution
• Fungal infections
• Inflammatory lung disease
Indications/contraindications for ablations
•Indications
• Papillary or follicular
• Ablate remnant tissue
• Decrease recurrence
•Contraindications
• Medullary and anaplastic
• Pregnancy/breastfeeding
Special considerations for ablation
• Incontinence
• Gastric sensitivities
• Elderly/known auditory conditions
• Dementias
Patient prep for ablations
•Patient’s home environment
•Ability to understand risks
•Ability to comply with instructions
•Support patient has from family
•Ability of patient to care for themselves
•Ability to minimize dose to others
•Discuss radiation safety
Patient pre-preparations
•Same as RAI WB surveys
•4-6 wks T4
•2 wks T3
•2 wks low iodine diet
•High TSH
• Hormone withdrawal or rTSH
3-5 day post ablation precautions
Avoid prolonged contact with others
• No close contact with children under 12 and pregnant
people
• Sleep alone
• Hydration
• Sour candy
1 week post ablation precautions
• Separate bathroom if possible
• Sit when urinating
• Flush twice
• Wash hands frequently
• Shower daily
• No kissing or sexual activity
• Launder towels and linens separately
• NO sharing food or drink
• Wash utensils separately
• Dispose of toothbrush
Additional in patient requirements post-ablation
•ALARA principles in effect BUT patient care should NOT be
compromised
• 20 uSv/hr @ 1 m general public
• Nurse, visitors, other patients
• Nursing care guidelines on Brightspace
• Patient in adjacent room
• < 500 uSv or < 2.5 uSv/hr
Acute ablation complications
• Nausea/vomiting
• Siladenitis (12%)
• Thyroiditis (20%)
• Dysphasia
• Stroke (rare)
Chronic complications after ablation
• Marrow hypofunction >18.5 GBq
• Leukemia >37 GBq
• Pulmonary fibrosis (lung mets)
• Xerostomia
• Hemorragic stroke (brain mets)
Ablation dose theory
• No mets (low risk): 1.1 - 1.9 GBq
• Regional mets: 1.85 - 3.7 GBq
• Distant mets: 3.7 - 7.4 GBq
Ablation procedure
•Patient preparation and consent
•Prep and deliver I-131 ablation dose
• Fumehood
• 37 MBq or more
• 100-150 feet/minute (0.5-0.75 m/sec)
• Vent dose prior to administration
• Minimize handling
• Double glove
• Wash hands
•Delayed imaging 5-7 days
