Summer 2006 DOE Practicum at the United
States Transuranium and Uranium Registries
Practicum Fellow: Deanna Hasenauer
4-Year DOE Health Physics Fellow
Affiliation: University of Florida (2000 – Present)
Advisors: Dr. Wesley Bolch (University of Florida)
and Dr. Anthony James (USTUR)
Nuclear and Radiological Engineering
Overview of Presentation
• Who am I?
– Pre-college
– Baccalaureate
– Post – Baccalaureate
• Ongoing research at the University of Florida
• My current area of research at the University of Florida
• Planned research at the USTUR (Summer 2006 practicum)
Nuclear and Radiological Engineering
A Bit of History: Pre-College
• Born in St. Petersburg, Florida
– March 15, 1982
• Mostly raised in Zephyrhills, Florida
• Zephyrhills High School (1996-2000)
– Played the flute in marching and symphonic band
• Superior solo performances
• All-county band (1st chair), All-district band, Festival of Winds (USF)
– Swim Team
• Held 6 records (still hold 4!!!) – 50 m free, 100 m free, 50 m butterfly,
various relays
• 1st female to attend state competition
– Valedictorian
Nuclear and Radiological Engineering
A Bit of History: Baccalaureate
• University of Florida (2000-2004)
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B.S. Nuclear and Radiological Engineering
Order of the Engineer
Alpha Nu Sigma
American Nuclear Society
Summa Cum Laude
Presented at 50th Annual
National HPS Conference
(Spokane, WA)
GO GATORS!!!!!
• Summer Internship (2003)
– Crystal River Unit 3 (Progress Energy)
– Reactor Engineering
Nuclear and Radiological Engineering
A Bit of History: Post - Baccalaureate
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Once a Gator . . . Always a Gator!
2006 Men’s Basketball National Champs!
GO GATORS!!!!!
•
DOE 4-year Health Physics Fellowship Award
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University of Florida (2004-2006)
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M. S. Nuclear and Radiological Engineering
Alpha Nu Sigma
American Nuclear Society
Society of Health and Medical Physics Students
• President (2005-2006)
– Present at 51st Annual HPS Conference (Providence, RI)
•
Summer DOE Practicum (2006)
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US Transuranium and Uranium Registries (USTUR)/WSU
Voxel phantom modeling of Case #0102
Human 241Am Phantom
Advisor: Dr. Anthony James
Nuclear and Radiological Engineering
Overview of Current Research Projects at UF
• Bone Imaging and Dosimetry (BID) Project Group
– Graduate Students: Deanna Hasenauer, Kayla Kielar, Carlos
Pichardo, Matthew Hough, Wendy Kresge
– Undergraduate Students: Laura Padilla (Senior), Lindsay Sinclair,
Jessica Salazar
– Post Doc: Vince Bourke
– Advisor: Dr. Wesley Bolch
• Other projects at UF (Dr. Wesley Bolch)
– Pediatric Organ Dose Project (POD)
– Center for Disease Control Project (CDC)
Nuclear and Radiological Engineering
My Research Area within the BID Group
• Development of image-based pediatric skeletal dosimetry
models for electrons and betas
Nuclear and Radiological Engineering
General Features of Bone
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Skeletal function
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Support
Store minerals/lipids
Protection
Leverage
Produce blood cells
Skeletal Structure:
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Epiphysis (CB/TB)
Diaphysis (No TB)
2 types:
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Cortical (compact) bone
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Cortical bone
Trabecular bone
Periosteum
Osteon
Haversian/Volksmann Canals
Trabecular (“spongy”) bone
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Network of irregular,
interlacing bone along lines
of stress
Cavities with active (“red”)
marrow and inactive
(“yellow”) marrow
50 - 4000µm marrow cavities
Age/skeletal site-specific;
intersubject variability
Nuclear and Radiological Engineering
Skeletal Development
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Static histomorphometry
– Histos: Web or tissue
– Morphe: Shape or form
– Metrikos: To measure
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Limited studies from bone biopsies
– Glorieux et al.
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Iliac Crest
Tb. Th. increases first decade of life, then unchanged
Increase in TBV and CBV
Decrease in TBS/TBV
Tb. N. invariant with age
– Roschger et al.
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L4
Tb. width increase, then unchanged from adolescence on
Decrease in Tb. N. after birth
Thin, dense network to then thicker, looser network
– Byer et al. (lumbar), Kneissel et al. (ribs), Beddoe et al.
(various)
• Rapid increase in marrow cavity size during infancy
• Gradual increase in marrow cavity size throughout
childhood
• Increase in Tb. Th. first decade of life
Nuclear and Radiological Engineering
Internal/External Dosimetry Applications
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Medical applications (bone marrow is dose-limiting organ – marrow toxicity)
– University of Florida
– Radioimmunotherapy (RIT)
• Tag tissue-specific antibody to beta-particle emitting radionuclide
• Cancers outside hematopoietic system (e.g. osteosarcomas, liver cancer, tumor growths)
– Radiotherapy
• Bone marrow ablation using external beam or bone-seeking radiopharmacuticals
• Localization of radiation within hematopoietic system
• Hodgkin’s or non-Hodgkin’s lymphoma; leukemia
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Radiation protection/epidemiological risk assessments
– USTUR and University of Florida
– Techa River contamination (about 30,000 people exposed)
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Mayak Production Association in Southern Urals of Russia (1949-1956)
Waste management failures and radioactive waste storage facility exposion
1017 Bq (~27 MCi) liquid waste (Sr, Cs, Y, Ba, La, I)
US – Russian JCCRER (Joint Coordinating Committee on Radiation Effects Research)
– Chernobyl accident (~5 million living in contaminated areas at time of release)
• Ukraine (1986)
• I-131 and Cs-137 (1018 Bq  about half biologically inert noble gases)
• Increase in thyroid cancer in children
– Leukemia risks from multiple CT exams and IVF
Nuclear and Radiological Engineering
Introduction – Historical Approach to Skeletal Dosimetry
– Historic perspective
• 40+ years of skeletal dosimetry research
– FW Spiers and colleagues at the University of Leeds
» 1949 - 1981
» Development of chord distributions used today
– Keith Eckerman and Michael Stabin at ORNL
» 1980s to present
» Development of current stylized (mathematical) Reference Man
model
» Development of ICRP pediatric age series models
(currently used in clinic – OLINDA and MIRDOSE)
– UF Bone Imaging and Dosimetry (BID) Group (late 1990s to now)
» Development of first “image-based” male tomographic model
» Development of first “image-based” female model (in progress)
» Development of first tomographic pediatric models (in progress)
Nuclear and Radiological Engineering
Historical Perspective – The ‘Founders’
• University of Leeds, UK
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Frederick “Bill” Spiers, Joan Whitwell, Philip Darley, and Alan Beddoe
First to assess modeling the complex microstructure of trabecular bone
Majority of microstructural data acquired in 1976 (Beddoe and colleagues)
Chord-length or path-length distributions
• 1.7 Y - Iliac crest, femur head, parietal bone, rib, and 3rd lumbar vertebra
• 9 Y - 4th cervical vertebra, humerus, rib, femur head and neck, iliac crest, and
femu shaft
• 44 Y - Parietal bone, femur head and neck, iliac crest, cervical vertebra, and
lumbar vertebra
– Known as infinite “chord-based” modeling through trabecular bone
• Electron energy completely expended in trabecular bone
• Used in current skeletal electron dosimetry models
Nuclear and Radiological Engineering
Research Initiatives at UF
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Image-based approach to skeletal modeling
– Voxel models to replace chord-based models
• Anatomically realistic skeletal shape/dimension
• Internally consistent masses
– First comprehensive adult male (Amish Shah)
– First comprehensive adult female (Kayla Kielar)
– In-vivo CT
• Some mass data
– Ex-vivo CT
• 3D shape and dimension of skeletal sites
– microCT
• 3D trabecular microstructure
– PIRT (Paired-Image Radiation Transport)
• Developed by Amish Shah
• Simultaneously couples macro-image and microimage to account for electron escape
Nuclear and Radiological Engineering
In-House Transport Codes
Nuclear and Radiological Engineering
Paired-Imaged Radiation Transport (PIRT)
• Amish Shah, HPJ 2005
• 66-Y male complete skeletal voxel model
• Simultaneous electron transport simulation within:
– Macrostructure (cortical bone, soft tissue, spongiosa)
• Ex-vivo CT imaging; 3D contour of true skeletal structure
– Microstructure (TAM50, TAM, TIM, TBV)
• microCT imaging; 3D image of skeletal spongiosa
Nuclear and Radiological Engineering
Chord-Based Infinite Spongiosa Transport (CBIST)
• Developed by Chris Watchman
• Macrostructure: None; infinite spongiosa
• Microstructure: University of Leeds chord
distributions
– Infinite trabecular bone, active/inactive
marrow
• 3D-CBIST: Cellularity dependence during
transport
Transport
radius
(380 mm)
D
C
Buffer
region
(120 mm)
B
Active
(red)
marrow
B
*
Adipocyte
(yellow
marrow)
A
 -track < sampled
marrow chord
70%
40%
20%
Nuclear and Radiological Engineering
Single-Image Radiation Transport (SIRT)
• Developed by Amish Shah
• Macrostructure: Ex-vivo CT imaging; 3D contour of true skeletal
structure
• Microstructure: None
• Coupled with EGSnrc (Electron-Gamma-Shower)
Nuclear and Radiological Engineering
Voxel-Based Infinite Spongiosa Transport (VBIST)
• Developed by Amish Shah
• Macrostructure: None; infinite spongiosa
• Microstructure: MicroCT imaging; 3D image of skeletal spongiosa
(coupled with EGSnrc)
Nuclear and Radiological Engineering
Limitations of Current Pediatric Electron Skeletal Dosimetry Models:
(Health Physics 2000, 2003)
• Transports through an infinite medium (infinite chord-based models)
– Does not account for particle escape from microstructure
• Accounts for cellularity after transport and not during transport
– Only valid at high electron energies (greater than 1 MeV)
– Bolch et al. (J Nucl Med – 2002)
• 10 micron endosteal layer model for osteogenic cells
– Recommended extension to 50 microns
– Gossner et al. (Radiation Protection Dosimetry – 2000, 2003)
• Skeletal masses are tied to stylized (mathematical) models
– Anatomically unrealistic
• Skeletal-averaged absorbed fraction data
– Significant changes in shape, size, and trabecular microstructure
– Beddoe et al. (Phys. Med. Biol. – 1976), Kneissel et al. (Calcif Tissue Int –
1997), Glorieux et al. (Bone – 2000), Byers et al. (Bone – 2000), Roschger et
al. (J of Structural Biology – 2001)
Nuclear and Radiological Engineering
Pediatric Skeleton: Reasons for Model Improvements
• Pediatric Skeleton
– Smaller skeletal macrostructure
• Increased electron energy escape  Reduced absorbed fraction
– Varying skeletal microstructure
• Higher % active marrow  Increased radiobiological effects
– Active bone marrow one of most radiosensitive tissues in the body
» ICRP 60 wT = 0.12
» Rapid cellular division
Law of Bergonie and Tribondeau
» Low cellular differentiation
» Long dividing future
• Smaller marrow cavities  More electron energy escape
• Thinner bone trabeculae  Less energy deposition in TBV
– Age at exposure
• Longer life expectancy after exposure  Increased probability of
secondary cancer inductions
Nuclear and Radiological Engineering
Pediatric Skeletal Modeling
• PIRT is ideal model for transport
– Microstructure (No 3D microCT data)
• What we do have . . .
– Macrostructure (UF pediatric series CT data)
• 9-month male, 4-year female, 8-year female, 11-year male, and 14-year male
• Scaled dimensions for each skeletal site
– Microstructure (studies at the University of Leeds in 1976)
• Cervical vertebra: 9-y, 44-y
• Lumbar vertebra: 1.7-y, 44-y
• Femur head and neck: 1.7-y (head only), 9-y (and shaft), 44-y
• Humerus: 9-y
• Iliac crest: 1.7-y, 9-y, 44-y
• Parietal bone: 1.7-y, 44-y
• Rib: 1.7-y, 9-y, 44-y
These are the only microstructural data for pediatric subjects
Nuclear and Radiological Engineering
Proposed Pediatric Skeletal Models:
Overview of SIRT-3DCBIST Model
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SIRT
– Accounts for particle escape from 3D voxelized macrostructure
– Skeletal masses, elemental compositions, densities are more anatomically refined
and applicable to tomographic phantoms (PEGS4 – Material dependent cross
section data for spongiosa, cortical bone, and soft tissue)
– Spongiosa self dose and cortical bone cross dose to spongiosa
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3D-CBIST
– TAM, TBV, TBS, TIM sources to TAMD, TAM50 (TAMS), TAM, TIM50 (TIMS), TIMD, TIM,
TBV targets
– Accounts for cellularity during transport from 10 keV to 100 keV
– 50 micron “shallow marrow” for osteogenic cell targets
– Curve-fit using hillslope in SigmaPlot between 100 keV and 1 MeV
– Scale by cellularity from 1 MeV to 10 MeV
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SIRT-3DCBIST
– Mathematically combine AF results from SIRT and 3D-CBIST to imitate “true” PIRT
results
Nuclear and Radiological Engineering
SIRT-3DCBIST Validation
1.00
SIRT-VBIST, PIRT, SIRT-3DCBIST Absorbed Fraction Comparison
Adult Iliac Crest at 100% Cellularity
TAM Targets
0.90
Absorbed Fraction
0.80
0.70
0.60
0.50
0.40
0.30
0.20
SIRT-VBIST (TAM)
PIRT (TAM)
SIRT-CBIST (TAM)
SIRT-VBIST (TBE)
PIRT (TBE)
SIRT-CBIST (TBE)
SIRT-VBIST (TBV)
PIRT (TBV)
SIRT-CBIST (TBV)
TBV Targets
TBE Targets
0.10
0.00
0.01
0.1
1
Electron Energy (Mev)
Nuclear and Radiological Engineering
10
In House Transport Model Comparisons
9-Month Sternum (96% Cellularity)
1.20
φ(TAMTBV)
SIRT
Absorbed Fraction
1.00
3D-CBIST
0.80
0.60
0.40
0.20
0.00
0.00
SIRT-3DCBIST
0.01
0.10
Electron Energy (MeV)
Nuclear and Radiological Engineering
1.00
10.00
Absorbed Fraction
0.25
SIRT-3DCBIST Absorbed Fraction Results
9-month Male (96% Cellularity)
φ(TAMCBV)
Sternum
Tibial heads
0.20
Fibular heads
0.15
0.10
Mandible
0.05
Cranium
0.00
0.00
0.01
0.10
Electron Energy (MeV)
Nuclear and Radiological Engineering
1.00
10.00
0.70
Skeletal-Averaged Absorbed Fraction Comparisons
between Current Model and SIRT-3DCBIST Model
9-Month Male (ICRP Reference Cellularity)
φ(TAMTBS)
Current Pediatric Model
Absorbed Fraction
0.60
0.50
51%
0.40
0.30
SIRT-3DCBIST
0.20
0.10
0.00
0.001
0.01
0.1
Electron Energy (MeV)
Nuclear and Radiological Engineering
1
10
Overall Conclusions
• Movement toward image (voxel)-based approaches in Medical and
Health Physics fields
– Anatomical accuracy (real 3D images)
– Realistic electron pathlength simulations (non-linear pathlengths)
– No chord-dependence (straight-line pathlength)
• EGSnrc interface used with SIRT, VBIST, and PIRT
– Allows user defined subroutines for any geometry and scoring options
without touching physics
– Preferred over MCNP with voxel-based images due to memory
• SIRT (macrostructure) and 3D-CBIST (microstructure) mathematical
combination for pediatric electron dosimetry models
– More anatomically accurate (electron escape and internally consistent
skeletal masses)
– Accounts for cellularity DURING transport
Nuclear and Radiological Engineering
My Research Area within the USTUR
• Development of VOXEL phantom and mathematical
modeling of detector configuration response for low
energy photons (241Am – 59.5 keV; 239Pu - 17 keV) for
USTUR case #0102
Nuclear and Radiological Engineering
USTUR Case # 0102:
DOE’s Human 241Am Phantom
• Half skeleton – encased in tissue
equivalent plastic – with simulated lungs.
• Died 1979 – age 50 – malignant melanoma.
• Lawrence Livermore Laboratory.
• Skeletal burden approx. 2 kBq (50 nCi) 241Am.
• Phantom distributed to DOE “in vivo” labs –
and internationally.
• Develop VOXEL phantom model from in-vivo
CT scanning (approximately 1mm axial slices)
– Kadlec Medical Center; Richland, WA
– G.E. CT/PET scanner for data acquisition
Nuclear and Radiological Engineering
Mathematical Modeling of Detector Response
• USTUR Case # 0990:
October 2005 Whole
Body Donor
•PNNL low- background
“in vivo” counting
facilities (thin planar Ge).
• Rocky Flats “Follow-up
Program ” participant –
died at age 82.
• Pu inhalation (1960s) –
with 30,000 ppm 241Am.
• Counters positioned for
liver.
Nuclear and Radiological Engineering
For More Information . . .
•
Dr. Anthony James (USTUR/WSU)
– tjames@tricity.wsu.edu
•
United States Transuranium and Uranium Registries
– www.ustur.wsu.edu
•
Dr. Wesley Bolch (Univ. of Florida)
– wbolch@ufl.edu
•
Deanna Hasenauer (USTUR/Univ. of Florida)
– ufdeanna@ufl.edu
– dhasenauer@tricity.wsu.edu
•
Advanced Laboratory for Radiation Dosimetry Studies (ALRADS) at the
University of Florida
– alrads.nre.ufl.edu
•
Department of Nuclear and Radiological Engineering at the University of
Florida
– www.nuceng.ufl.edu
Nuclear and Radiological Engineering