RADIOIODINE THERAPY

Where does iodine go in the body?

• A) bone• B) lung• C) heart• D) thyroid

What does the word ablate mean?

• A) cure• B) destroy• C) help• D) increase absorption

What is a reason for RN Therapy?

• A) ablate cancer• B) palliative treatment• C) used instead of chemotherapy• D) used instead of radiation therapy

What is Radionuclide Therapy ?

• The use of a radionuclide, generally as a liquid or suspension, to treat

and ablate tumors or;

• as a palliative agent to reduce pain in patients who are considered

terminally ill.

I-131 Sodium Iodide Therapy

• Principle: I-131 is concentrated and retained in thyroid tissue. The beta (β-) emission of I-131 delivers localized radiation to the area

• Clinical Applications:– Hyperthyroidism: the objective is to render the patient

euthyroid – Thyroid carcinoma: the objective is to ablate (destroy)

residual thyroid tissue and functioning metastases

http://www.thyroidmanager.org/Chapter21/figures/figure12.png

Therapy for Hyperthyroidism• Amount of radioactivity to be administered is based

on size of gland and radioiodine uptake(dosages may range from ~5- ~33 mCi)

• Patient preparation:– Off thyroid medications– Fasting– Check for swallowing difficulty– Remove dental appliances– Pregnancy test

Instructions to patient regarding radiation safety precautions:

- Review routes of radioiodine excretion - Use own bathroom if possible- Flush twice; wash hands thoroughly- No intimate contact for 2 wks- Don’t share eating utensils/towels- Wash personal clothing separately - Flush tissues; don’t throw in trash- Avoid public places for 2 wks- Avoid holding children; maintain distance from

others

Therapy for Thyroid Cancer

• Typical dosage: 50-200 mCi

• It may be necessary to place the patient in isolation. NRC regulations require isolation if the estimated radiation dose to a member of the public will exceed 500 mrem

• Patient preparation– Same prep as for hyperthyroid therapy– Instruct patient regarding isolation requirements (visitors,

urine, nursing care, other) or instructions for the home and public places

– Prepare patient psychologically for isolation

• Isolation room preparations– Paper flat surfaces, door knobs, etc.– Post door to room– Linens, eating utensils, trash

I-131 Therapy Room View

I-131 Therapy Door Handles

Door handle leaving patient room Door handle entering bathroom

I-131 Therapy Bathroom

I-131 Therapy Covered ChairPatient Comments:

-“The tape on the chair would never secure the covering to the chair sufficiently.”

-“I kept borrowing tape from other parts of the room to re-tape it but is was still ineffective.”

I-131 Therapy Room

Disposable stethoscope & cuffPlastic covered phone

TV remote on dining tray

Pt. Comment: “You could not hear or speak well through plastic covering-just used cell phone instead.”

I-131 Therapy Biohazard ContainerPatient Comments:

- “Had two biohazard containers one for trash one for linens”

-“Supplied with several gowns, bath linens and bed linens.”

-“Showered 3-4 times a day and used new towels and changed into new gowns”

-“Food served on disposable trays and everything on tray was disposable so that one could put it all in biohazard container when done”

-”If got normal trays, had to stack cups, trays, utensils in room.”

“Dietary people would knock on the door, hand (throw) the tray quickly at you and rush off”

There is accumulation of I-131 in the neck, salivary glands, gastrointestinal tract, and bladder. Additionally, there is subtle activity extending superiorly from atop the patients head in an unusual "fountain-like" fashion on the anterior image. On the posterior view, there is activity in a broad distribution over the back of the head just superior to the large focus in the neck.

http://gamma.wustl.edu/tr006te129.html

• Nursing personnel– Whole body dosimetry– No pregnant personnel– Restrict bedside nursing

• Monitoring for release from isolation– Don’t predict– Monitor with ionization chamber

• Discharge instructions to patient

http://images.google.com/imgres?imgurl=http://www.endoconsultants.com/Lab/3400_testsoftfunction.gif&imgrefurl=http://www.endoconsultants.com/Lab/Thyroidtests.htm&h=345&w=288&sz=18&hl=en&start=117&usg=__jCZLQx8ZJAlMeYOaV8w78kPnj94=&tbnid=CQHCNC_Pw8e9M:&tbnh=120&tbnw=100&prev=/images%3Fq%3Dradioiodine%2Btherapy%26start%3D108%26gbv%3D2%26ndsp%3D18%26hl%3Den%26sa%3DN

Instructions to I131 Therapy Patients Prior to Discharge

• Routes of iodine excretion– Urine– Perspiration– Sputum/saliva– Tears

• Avoidance of certain activities– Prolonged personal contact – children, partner, etc.– Sharing of eating utensils– Sharing of linens– Breast-feeding – should be suspended for at least 80

days• Double flushing the toilet after use• Frequent hand washing

Radiotherapy Concerns• I131 Thyroid Ablation Patient = main

concern• I131 – can be excreted in all bodily fluids –

sweat, saliva, urine, tears. • At normal room temperature it can go to

gas form into the room air.• Inhalation of I131 gas can result in thyroid

uptake to anyone who is exposed to it.

General Dose Limits I131 Therapy• Nurses – limited to ~ 50mRem/24 hours

• Visitors – limited to ~ 20mRem/24 hours

• Unrestricted Areas – limited to 2mRem/ hour

• Minors (under 18 Y/O) – generally not allowed access unless Authorized User (AU) approves.

TOTAL BODY IMAGINGWITH RADIOIODINE

Total Body Imaging with I-131 NaI Follow-Up of Thyroid Cancer

Purpose:

1) To determine the presence/extent of residual functioning thyroid tissue following surgery/radioiodine therapy

2) To determine the presence/location of functioning thyroid cancer (metastases)

Clinical Procedure

1) ID patient; verify physician’s order; review clinical indication for imaging

2) Explain procedure to patient; obtain relevant history

Relevant Medical History• Patient’s compliance with

low iodine diet; discontinuation of medications

• TSH/thyroglobulin levels

• Thyroid surgery information – extent, tumor pathology

• Results of other imaging procedures

• Physical exam findings

• History of prior radioiodine administration for imaging or therapy

http://www.endoconsultants.com/Lab/3400_testsoftfunction.gif

Clinical Procedure (cont’d)3) Patient preparation

- discontinue medications that affect concentration of iodine or that contain iodine

- low iodine diet for 3-10 days prior to and during imaging

- measure TSH level (should be > 30-50 mU/L)- mild laxatives day before imaging- review radiation safety precautions- pregnancy test – to document pregnancy is not an issue- lactation history

Clinical Procedure (cont’d)

4) Administer 1-5 mCi I-131 or I-123 sodium iodide orally

5) Image patient 48-72 hrs post tracer administration- Anterior/posterior from top of head to mid-

thigh/knees; extremities/laterals/obliques as needed

- Use radioactive markers on anatomical landmarks

Sources of Error• Contamination

– I-131 and I-123 sodium iodide are excreted in the urine, saliva, and perspiration

- Protect self and equipment

- Take precautions to prevent contamination artifacts on images

- Stunning - Stunning is best recognized 1 to 3 days after therapeutic I-131

Top: diagnostic I-131; Bottom: little or no uptake of therapeutic I-131 because the lesions were stunned by the diagnostic I-131

http://images.google.com/imgres?imgurl=http://www.ncku.edu.tw/~nuclmed/teach/stunni11.jpg&imgrefurl=http://www.ncku.edu.tw/~nuclmed/teach/stunning_I131.html&h=249&w=466&sz=18&hl=en&start=2&usg=__8EFUe_Izd9DyoVuGVxLXznlH5l8=&tbnid=LrBhViOTZmALFM:&tbnh=68&tbnw=128&prev=/images%3Fq%3Dradioiodine%2Bwhole%2Bbody%2Bimage%26gbv%3D2%26hl%3Den for slides 17 -20

Stunning is best recognized 1 to 3 days after therapeutic I-131. (A) A postoperative diagnostic scan showing remnants. (B) ablative I-131 therapy was given 2 weeks later. 48 hr posttherapy scan shows no appreciable uptake. (C) a 7-day posttherapy scan shows some of the cells in the stunned lesion can trap minimal amount of iodine if sufficient time is allowed.

I-123 does not stun the thyroid.

I-123 whole body scan. Salivary radioiodine in the esophagus: linear activity in the

midline chest is a possibility