Nuclear Medicine Physics Radioiodine Therapy Jerry Allison, Ph.D. Department of Radiology Medical College of Georgia

Medical College of Georgia And Sameer Tipnis, Ph.D. A note of thanks to Z. J. Cao, Ph.D. Medical College of Georgia And Sameer Tipnis, Ph.D. G. Donald Frey, Ph.D. Medical University of South Carolina for Sharing nuclear medicine presentation content

http://www.hpschapters.org/northcarolina/fall2008/TPM.3.pdf

http://www.hpschapters.org/northcarolina/fall2008/TPM.3.pdf

Thyroid Uptake/Imaging I-123: 100 – 200 mCi (g only) T1/2 = 13.2 h 1-131: 15 – 100 mCi (g & b) T1/2 = 8 d

Thyroid probe Measure thyroid uptake of I-131 in-vivo 5×5 cm NaI(Tl) with 15 cm long conical collimator pointing to neck and thigh (bkg) calibration phantom with known activity for calculating uptake (pt capsule) 1 – 2 cm difference in depth  10 – 40% difference in count rate

Thyroid uptake neck phantom For use with thyroid uptake probe. Used to estimate atteuation and scatter for soft tissue overlying thyroid glad. Approximates typical patient neck geometry. http://www.biodex.com/nuclear-medicine/products/thyroid-uptake-system/thyroid-uptake-system-accessories/thyroid-uptake-nec

Thyroid http://www.hpschapters.org/northcarolina/fall2008/TPM.3.pdf

- Emitters - (beta) - 131I, 90Y, 153Sm 2015 Nuclear Medicine Physics for Radiology Residents Sameer Tipnis, PhD, DABR

b- decay A neutron decays to a proton, electron and anti- neutrino: n  p + e- +. e- and created inside the nucleus at the moment of decay and ejected instantaneously AXz  AYz+1 e.g. 131I53  131Xe54 + e- + e- 

Applications - emitters – used for therapy - cannot escape pt, localized energy deposition 90Y (pure -) 131I , 153Sm (- and ) 2015 Nuclear Medicine Physics for Radiology Residents Sameer Tipnis, PhD, DABR

131I Production Reactor produced as fission product

131I Decay © Physics in Nuclear Medicine: Cherry, Sorenson and Phelps

131I Decay https://en.wikipedia.org/wiki/File:Iodine-131-decay-scheme-simplified.svg

I-131 Absorbed Dose 90% of pt dose is b; 10% by g http://www.nuclearonline.org/PIbyGeneric2.htm

Written directive Required for I-131 dose exceeding 30 μCi Pregnancy test results Order for the radiopharmaceutical is written twice Once to order the drug The second dosage usually represents the actual amount given Route of administration Must be signed by an authorized user

NM Written Directive for I-131 Therapy http://www.gru.edu/services/ehs/radsafe/

Authorized User A physician licensed to practice and who meets specific requirements (NRC) and identified as an AU on the institution’s license or permit Board Certified (by appropriate Board) Other physicians and technologists may work with byproduct material under the supervision of an AU All radiopharmaceuticals dispensed or administered must be pursuant to an order (e.g. prescription) of an AU 2015 Nuclear Medicine Physics for Radiology Residents Sameer Tipnis, PhD, DABR

Authorized User 10CFR35.290 Training for imaging and localization studies Has completed 700 hours of training and experience, including a minimum of 80 hours of classroom and laboratory training http://www.nrc.gov/reading-rm/doc-collections/cfr/part035/part035-0290.html

Authorized User 10CFR35.390 Training for use of unsealed byproduct material for which a written directive is required Has completed 700 hours of training and experience, including a minimum of 200 hours of classroom and laboratory training http://www.nrc.gov/reading-rm/doc-collections/cfr/part035/part035-0390.html

Authorized User 10CFR35.392 Training for the oral administration of sodium iodide I-131 requiring a written directive in quantities less than or equal to 1.22 gigabecquerels (33 millicuries) Administering dosages to patients …, that includes at least 3 cases involving the oral administration of less than or equal to 1.22 gigabecquerels (33 millicuries) of sodium iodide I-131 http://www.nrc.gov/reading-rm/doc-collections/cfr/part035/part035-0392.html

Authorized User 35.394 Training for the oral administration of sodium iodide I-131 requiring a written directive in quantities greater than 1.22 gigabecquerels (33 millicuries) Administering dosages to patients …, that includes at least 3 cases involving the oral administration of greater than 1.22 gigabecquerels (33 millicuries) of sodium iodide I-131 http://www.nrc.gov/reading-rm/doc-collections/cfr/part035/part035-0392.html

131I studies For 131I doses > 30 µCi a “written directive” which may only be issued by an AU is required for each treatment Radiology residents (under AU supervision) need to direct 3 treatments < 33 mCi and 3 > 33 mCi to be “AU Eligible” 2015 Nuclear Medicine Physics for Radiology Residents Sameer Tipnis, PhD, DABR

Getting “AU Eligible” Radiology Residents who Complete the requirements during their residency Get “OK” from the residency director Pass the RISE exam (part of core exam) Radioisotope Safety Exam (~60 items) ~15 NM physics items ~15 NM safety items ~20 NM clinical items ~20 NM regulatory/administrative items 2015 Nuclear Medicine Physics for Radiology Residents Sameer Tipnis, PhD, DABR

COMPLIANCE WITH NRC TRAINING AND EXPERIENCE REQUIREMENTS

Release of I-131 therapy patients I-131 in patients may be excreted in their urine, perspiration and saliva and these body fluids can contaminate household surfaces. Use separate bathroom Shower/brush teeth frequently Limit hugs, sleep alone Limit visitors and co-workers Limited length of stay time

Release of I-131 therapy patients Avoid public transportation Children, pregnant women and nursing mothers must stay at least 6’ away. Written instructions must be provided to the patient to minimize radiation exposure to public if a member of the public could receive a dose greater than 1 mSv.

Radioiodine Safety Manuals at MCG http://www.gru.edu/services/ehs/radsafe/

Radioiodine Procedures and Nursing Instructions http://www.gru.edu/services/ehs/radsafe/

Signage Radioactive Material Entry Log Instructions No Housekeeping

Shoe covers, absorbent floor pads

Plastic sheeting, absorbent floor pad, furniture covers

Disposable trash container (hazardous)

Bed rails covered

Toilet cover

Sink cover

Vanity cover

Absorbent sink cover

Door handle covers

Release of I-131 therapy patients A patient may be released if the total effective dose to any other individual (family or caregiver) is not likely to > 5 mSv Patients receiving diagnostic nuclear medicine examinations can be released without any calculations 131I Therapy patients need special instructions 2015 Nuclear Medicine Physics for Radiology Residents Sameer Tipnis, PhD, DABR

Radiation exposure rate around patient Typical exposure rate at 1 m from the patient soon after injection: Most diagnostic radiopharmaceuticals: <1 mR/hr (maximum dose to public 1 mSv/yr) 18F-FDG: ~5 - ~30 mR/hr 131I: ~5 or ~30 mR/hr for Graves or cancer dose respectively

Breast feeding Guidelines (recommended / not regulated) Radiopharmaceutical Recommendation 131I NaI Cessation 123I NaI 67Ga Citrate 201Tl Chloride 96 hrs 123I MIBG, 99mTc WBC 48 hrs 99mTc MAA, 99mTc RBC 12 hrs 2015 Nuclear Medicine Physics for Radiology Residents Sameer Tipnis, PhD, DABR

Lactating 131I therapy pts Lactating breasts accumulate radioiodine Patient breast dose can be quite high Breast pump reduces breast dose Lactating completely ceases  4 wks post-partum with no breast feeding Ask pt to stop breastfeeding 15 days BEFORE therapy 2015 Nuclear Medicine Physics for Radiology Residents Sameer Tipnis, PhD, DABR

Absorbed dose to fetus 99mTc MAA 0.35 (mSv/mCi) 99mTc sulfur colloid 0.35 99mTc RBC 0.60 99mTc DTPA 0.35 99mTc diphosphonate 0.40 67Ga citrate 2.50 111In leukocytest 4.00 131I (15% uptake) 1.00 123I (15% uptake) 0.35 201Tl chloride 3.00 133Xe 0.01

Fetal thyroid dose from 131I 131I can rapidly cross the placenta Fetal thyroid starts concentrating 131I after 11 to 12th week post-conception Ability rapidly increases after 22nd week Can result in hypothyroidism / ablation Critical to check pt for pregnancy before 131I therapy 2015 Nuclear Medicine Physics for Radiology Residents Sameer Tipnis, PhD, DABR

Homeland security Extremely sensitive radiation detectors are deployed in train stations, airports, tunnels, etc. I-131 patients may set off alarms up to 95 days following a therapy procedure. Give a letter containing radionuclide and hospital contact information.

What is major spill? Activity released at location or on people 100 mCi Tc-99m or Tl-201 10 mCi Ga-67 or In-111 1 mCi I-131 Radiation safety officer must be present. Focus on containment, shielding, and decontaminating individuals