Nuclear and Radiological Engineering Summer 2006 DOE Practicum at the United States Transuranium and...

Nuclear and Radiological Engineering

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)


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)


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


A Bit of History: Baccalaureate

• University of Florida (2000-2004) – 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)

• Summer Internship (2003)– Crystal River Unit 3 (Progress Energy)– Reactor Engineering

GO GATORS!!!!!


A Bit of History: Post - Baccalaureate

• Once a Gator . . . Always a Gator! • 2006 Men’s Basketball National Champs!

• DOE 4-year Health Physics Fellowship Award

• University of Florida (2004-2006) – 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)– US Transuranium and Uranium Registries (USTUR)/WSU– Voxel phantom modeling of Case #0102– Human 241Am Phantom– Advisor: Dr. Anthony James

GO GATORS!!!!!


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)


My Research Area within the BID Group

• Development of image-based pediatric skeletal dosimetry models for electrons and betas


General Features of Bone• Skeletal function

– Support– Store minerals/lipids– Protection– Leverage– Produce blood cells

• Skeletal Structure:– Epiphysis (CB/TB)– Diaphysis (No TB)– 2 types:

• Cortical bone• Trabecular bone

– Cortical (compact) bone• Periosteum• Osteon• Haversian/Volksmann Canals

– Trabecular (“spongy”) bone• 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


Skeletal Development• Static histomorphometry

– Histos: Web or tissue– Morphe: Shape or form– Metrikos: To measure

• Limited studies from bone biopsies– Glorieux et al.

• 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.• 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


Internal/External Dosimetry Applications

• 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

• Radiation protection/epidemiological risk assessments – USTUR and University of Florida– Techa River contamination (about 30,000 people exposed)

• 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


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)


Historical Perspective – The ‘Founders’

• University of Leeds, UK – 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


Research Initiatives at UF

• 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 micro-image to account for electron escape


In-House Transport Codes


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


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

Adipocyte(yellow marrow)

-track < sampled marrow chord

Buffer region (120m)

Transport radius(380 m)

Active (red) marrow

B*

B

A

CD

70% 40% 20%


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)


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)


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)


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» 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

Law of Bergonie and Tribondeau


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


Proposed Pediatric Skeletal Models:

Overview of SIRT-3DCBIST Model • 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

• 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

• SIRT-3DCBIST– Mathematically combine AF results from SIRT and 3D-CBIST to imitate “true” PIRT

results


SIRT-3DCBIST Validation

SIRT-VBIST, PIRT, SIRT-3DCBIST Absorbed Fraction Comparison Adult Iliac Crest at 100% Cellularity

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

0.80

0.90

1.00

0.01 0.1 1 10

Electron Energy (Mev)

Abs

orbe

d Fr

actio

n

SIRT-VBIST (TAM)

PIRT (TAM)SIRT-CBIST (TAM)

SIRT-VBIST (TBE)

PIRT (TBE)SIRT-CBIST (TBE)

SIRT-VBIST (TBV)

PIRT (TBV)SIRT-CBIST (TBV)

TAM Targets

TBV Targets

TBE Targets


φ(TAMTBV)

0.00

0.20

0.40

0.60

0.80

1.00

1.20

0.00 0.01 0.10 1.00 10.00

Electron Energy (MeV)

Abs

orbe

d Fr

actio

n

SIRT

SIRT-3DCBIST

3D-CBIST

In House Transport Model Comparisons9-Month Sternum (96% Cellularity)


φ(TAMCBV)

0.00

0.05

0.10

0.15

0.20

0.25

0.00 0.01 0.10 1.00 10.00

Electron Energy (MeV)

Abs

orbe

d Fr

actio

n

Cranium

Sternum

Fibular heads

Tibial heads

Mandible

SIRT-3DCBIST Absorbed Fraction Results9-month Male (96% Cellularity)


φ(TAMTBS)

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

0.001 0.01 0.1 1 10Electron Energy (MeV)

Ab

sorb

ed F

ract

ion

SIRT-3DCBIST

Current Pediatric Model

51%

Skeletal-Averaged Absorbed Fraction Comparisons between Current Model and SIRT-3DCBIST Model

9-Month Male (ICRP Reference Cellularity)


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


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


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


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.


For More Information . . . • Dr. Anthony James (USTUR/WSU)

– [email protected]

• United States Transuranium and Uranium Registries– www.ustur.wsu.edu

• Dr. Wesley Bolch (Univ. of Florida)– [email protected]

• Deanna Hasenauer (USTUR/Univ. of Florida)– [email protected]– [email protected]

• 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

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