endocrine oral

What is the MOA of I-123 and TcO4- into the thyroid?

Active transport

What findings on a thyroid scan indicate Graves disease

Increased homogenous uptake throughout the whole thyroid 

diffusely enlarged gland

4 clinical indications for performing thyroid uptake and imaging

Evaluate hyper, hypo

Look for mets or cancer

Evaluate abnormal TSH

Evaluate nodule

What is on a written directive

Signature of Authorized user and tech

Date

RPx

Prescribed dose

Given measured dose

patient information

route of administration (oral, iv, etc)

What is patient prep for I-131 therapy dose

Previous uptake and scan or ultrasound to help determine the dose

Preg test, no breastfeeding

Doc has to come in and explain test

Informed consent

Written directive

No CT with contrast

Low iodine diet

NPO 4 hours

certain meds must be stopped

Clinical indications for I-131 whole body imaging

Detection of residual thyroid tissue

detection of mets

Evaluation of recurrence

Localization of functioning thyroid tissue

Describe procedure for an I-131 WB imaging after thyroidectomy

Instructed of all prep (low iodine diet, npo, no preg, no iodiated constrast)

Questionnaire of symptoms

Give I-131 pill (2-5 mCi)

Leave

Come back 3-4 days later

WB scan

Need high energy collimator HEHR —— higher keV need to block out higher energy so photons don’t easily penetrate through

Explain how patients thyroid meds will affect quality of procedure

Falsely decrease uptake (competitive binding)

A pt with primary hyperthyroidism will have ____ TSH ____free T4, ____T3

Low TSH

High T4

High T3

A patient is suspected of having substernal thyroid tissue. What would be the best RPx to eval this tissue and why

I-123 because if you use tc, it gets taken up by the thymus which will make it hard to determine if it's the thymus or substernal tissue

How do you assess pregnancy prior to an I-131 administration

blood test

A 32 yo woman has weight loss, heat intolerance, palpitations and tremors. Exam reveals a diffuse goiter and bulging eyes. Labs show low TSH and high T3 t4. NM test shows high pertechnetate uptake in thyroid throughout gland with no nodules

Primary hyperthyroidism, graves disease

Explain calibration procedure for uptake probe

Linearity : Eu-157 (Europium-157)

Accuracy and energy calibration : Cs-137

A patient forgets to tell you they are on amiodarone. How will this affect images

significant decrease uptake because it has a lot of iodine in it 

which saturates the thyroid and blocks radioactive iodine uptake.

four most commonly used pharmaceuticals for thyroid?

I123, I131, TcO4, TI201

I-123 half life and keV

13.2 hours and 159 kev

I-131 half life and kev?

8.06 days and 364 & 605 kev

TcO4- half life and kev?

6 hrs and 140 kev

TI-201 half life and kev?

73.1 hrs and 80, 167, 135 kev

dose for I-123 and rays?

200-400 uci and gamma rays

which is the pharmaceutical of choice and why?

I-123 bc it gives acceptable radiation doses and it is also trapped and organified by normal thyroid tissue

disadvantages to I-131?

-poor spatial resolution

-larger radiation dose

-long half life makes sequential studies harder

dose for I-131 oral whole body scans?

2-5 mci

dose for I-131 thyroid ablation?

80-150 uci per gram of thyroid tissue

dose of I-131 for thyroid carcinoma?

100-200 mci

if there is a hot spot with TcO4- and a cold spot with another imaging agent, what does that mean?

possibly cancerous- cold nodules with tc99m will be cold with iodine

TI-201 is used when wanting to see what?

thyroid carcinoma, cold thyroid nodules. since tumors often uptake this

steps to doing uptake?

-background of the room

-count the pill in the phantom

-1 min count at thigh

-1 min count at neck

equation for calculating uptake?

neck counts - thigh counts/ standard counts - background ounts X100= %

what do hot nodules indicate?

-plummers nodule

-normal tissue

-focal hyperplasia (a common, benign, non-neoplastic liver tumor)

primary, secondary and tertiary hyper?

primary: thyroid problems, (Graves, Plummers)

secondary: pituitary problems (pituitary adenomas)

tertiary: hypothalamus problems

hypothyroidism is caused by what?

the glands fail to make and release thyroid hormone

indications for whole body I-131 imaging?

-evaluate residual thyroid tissue after thyroidectomy

-evaluate residual thyroid tissue after ablative therapy

what collimators are used for I131 whole body image?

high energy

if the patient does now follow the low iodine diet before their ablative therapy what can happen?

thyroid storm which releases stored thyroid hormone into the circulation

where is TRH produced?

hypothalamus

where is TSH produced?

anterior pituitary

Endocrine system consists of?

pituitary, thyroid, parathyroids, adrenals, thymus, pancreas, pineal, ovaries (female), and testes (male)

pt with primary hypothyroidism will have ____ TSH ____free T4, ____T3

↑ TSH,

↓ free T4

, ↓ T3

Collimator for uptake probe?

Flat field

what is the use of the fumehood?

pushes contaminated air outside to reduce inhalation

how do you measure staff exposure?

use probe after preparation or administration, you can also place under the scanner to see any radioactivity

parathyroid imaging protocol

name dob

Inject patient with 20-30 mCi of Sestamibi,

wait 15-20 minutes

take views same as thyroid: anterior with heart in view (ectopic tissue) and 30 degree RAO/LAO acquired for 100k counts

then 2 hours delays same images

Follow either set of images with a SPECT/CT

clinical findings for hypo.hyper

Hyperthyroidism (↑ thyroid hormone)

Clinical findings:

Weight loss (despite ↑ appetite)

Heat intolerance, sweating

palpitations

Anxiety, tremor

Diarrhea

Insomnia

Hypothyroidism (↓ thyroid hormone)

Clinical findings:

Weight gain

Cold intolerance

Fatigue, lethargy

Bradycardia

Constipation

Depression

what would hyperparathyroid look like on a scan

persistant activity in delayed images

if ur doing an uptake scan and at 6 hours you measure 24cm and 24 hours you measure at 20 what will happen to results

24 hr will be falsly elevated since its closer it will recieve more counts and look like it took up more iodine when it rly just was closer

what RPx would u use to locate ectopic thyroid tissue

I-123 bc TcO4- it will go to salivary glands and may cause confusion when identifying ectopic tissue vs normal tissue