Jerry Allison PhD Department of Radiology Medical College of Georgia Radioiodine Therapy A note of thanks to Z J Cao PhD Medical College of Georgia And Sameer Tipnis PhD G Donald Frey PhD ID: 779705
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Slide1
Nuclear Medicine Physics
Jerry Allison, Ph.D.Department of RadiologyMedical College of Georgia
Radioiodine Therapy
Slide2A note of thanks to Z. J. Cao, Ph.D.Medical College of GeorgiaAnd
Sameer Tipnis, Ph.D.G. Donald Frey, Ph.D.Medical University of South Carolina
forSharing nuclear medicine
presentation content
Slide3http://www.hpschapters.org/northcarolina/fall2008/TPM.3.pdf
Slide4http://www.hpschapters.org/northcarolina/fall2008/TPM.3.pdf
Slide5Thyroid Uptake/ImagingI-123: 100 – 200 mCi (g only)
T1/2 = 13.2 h1-131: 15 – 100 mCi (g & b)
T1/2 = 8 d
Slide6Thyroid probe Measure thyroid uptake of I-131 in-vivo
5×5 cm NaI(Tl) with 15 cm long conical collimatorpointing 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
Slide7Thyroid uptake neck phantomFor 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
Slide8Thyroidhttp://www.hpschapters.org/northcarolina/fall2008/TPM.3.pdf
Slide9- Emitters-
(beta) - 131I, 90Y, 153Sm 2015 Nuclear Medicine Physics for Radiology Residents Sameer Tipnis, PhD, DABR
Slide10b- 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 AX
z
A
Y
z+1
e.g.
131
I
53
131
Xe
54
+ e
-
+
e
-
Slide11Applications- emitters – used for therapy- ca
nnot escape pt, localized energy deposition 90Y (pure -)131I , 153Sm (- and
)2015 Nuclear Medicine Physics for Radiology Residents Sameer Tipnis, PhD, DABR
Slide12131I ProductionReactor produced as fission product
Slide13131I Decay
© Physics in Nuclear Medicine: Cherry, Sorenson and Phelps
Slide14131I Decayhttps://en.wikipedia.org/wiki/File:Iodine-131-decay-scheme-simplified.svg
Slide15I-131 Absorbed Dosehttp://www.nuclearonline.org/PIbyGeneric2.htm
90% of pt dose is b; 10% by g
Slide16Written directiveRequired for I-131 dose exceeding 30 μCi
Pregnancy test resultsOrder for the radiopharmaceutical is written twiceOnce to order the drugThe second dosage usually represents the actual amount givenRoute of administrationMust be signed by an authorized user
Slide17NM Written Directive for I-131 Therapyhttp://www.gru.edu/services/ehs/radsafe/
Slide18Authorized UserA 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
Slide19Authorized User10CFR35.290 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
Slide20Authorized 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
Slide21Authorized 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
Slide22Authorized 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
Slide23131I studiesFor 131I doses > 30 µCi a “written directive” which may only be issued by an
AU is required for each treatmentRadiology 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
Slide24Getting “AU Eligible”Radiology Residents who Complete the requirements during their residencyGet “OK” from the residency directorPass 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 items2015 Nuclear Medicine Physics for Radiology Residents Sameer Tipnis, PhD, DABR
Slide25COMPLIANCE WITH NRC TRAINING AND EXPERIENCE REQUIREMENTS
Slide2626Release of I-131 therapy patientsI-131 in
patients may be excreted in their urine, perspiration and saliva and these body fluids can contaminate household surfaces.Use separate bathroomShower/brush teeth frequentlyLimit hugs, sleep aloneLimit visitors and co-workers
Limited length of stay time
Slide2727Release of I-131 therapy patientsAvoid public transportationChildren, 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
.
Slide28Radioiodine Safety Manuals at MCGhttp://www.gru.edu/services/ehs/radsafe/
Slide29Radioiodine Procedures and Nursing Instructionshttp://www.gru.edu/services/ehs/radsafe/
Slide30SignageRadioactive Material
Entry LogInstructionsNo Housekeeping
Slide31Shoe covers, absorbent floor pads
Slide32Plastic sheeting, absorbent floor pad, furniture covers
Slide33Disposable trash container (hazardous)
Slide34Bed rails covered
Slide35Toilet cover
Slide36Sink cover
Slide37Vanity cover
Slide38Absorbent sink cover
Slide39Door handle covers
Slide40Release of I-131 therapy patientsA patient may be released if the total effective dose to any other individual (family or caregiver) is not likely to > 5 mSvPatients receiving diagnostic nuclear medicine examinations can
be released without any calculations131I Therapy patients need special instructions2015 Nuclear Medicine Physics for Radiology Residents Sameer Tipnis, PhD, DABR
Slide41Radiation exposure rate around patientTypical 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
/hr131I: ~5 or ~30 mR/hr for Graves or cancer dose respectively
Slide42Breast feeding Guidelines (recommended / not regulated)Radiopharmaceutical
Recommendation
131
I NaI
Cessation
123
I
NaI
Cessation
67
Ga Citrate
Cessation
201
Tl Chloride
96
hrs
123
I MIBG,
99m
Tc WBC
48
hrs
99m
Tc MAA,
99m
Tc RBC
12
hrs
2015 Nuclear Medicine Physics for Radiology Residents Sameer Tipnis, PhD, DABR
Slide43Lactating 131I therapy ptsLactating breasts accumulate radioiodinePatient breast dose can be quite highBreast pump reduces breast doseLactating completely ceases
4 wks post-partum with no breast feedingAsk pt to stop breastfeeding 15 days BEFORE therapy2015 Nuclear Medicine Physics for Radiology Residents Sameer Tipnis, PhD, DABR
Slide4444Absorbed dose to fetus
99mTc MAA 0.35 (mSv/mCi)
99mTc sulfur colloid 0.3599mTc RBC 0.60
99mTc DTPA 0.3599mTc diphosphonate
0.40
67
Ga citrate 2.50
111
In
leukocytest
4.00
131
I (15% uptake) 1.00
123
I (15% uptake) 0.35
201
Tl chloride 3.00
133
Xe 0.01
Slide45Fetal thyroid dose from 131I131I can rapidly cross the placentaFetal thyroid starts concentrating 131I after 11 to 12th week post-conception
Ability rapidly increases after 22nd weekCan result in hypothyroidism / ablationCritical to check pt for pregnancy before 131I therapy2015 Nuclear Medicine Physics for Radiology Residents Sameer Tipnis, PhD, DABR
Slide4646Homeland securityExtremely 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.
Slide47What is major spill?Activity released at location or on people100 mCi Tc-99m or Tl-20110 mCi
Ga-67 or In-1111 mCi I-131Radiation safety officer must be present.Focus on containment, shielding, and decontaminating individuals