Hot stuff
Download
1 / 54

HOT STUFF - PowerPoint PPT Presentation


  • 301 Views
  • Uploaded on

HOT STUFF. Ionizing Radiation in Medicine. Objectives. History of nuclear medicine Benefits of Nuclear Medicine Radiation Biology: interactions and effects Diagnostic and Therapeutic Applications Common Nuclear Medicine procedures. Overview. Over 20 million procedures annually in US

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'HOT STUFF' - PamelaLan


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
Hot stuff l.jpg

HOT STUFF

Ionizing Radiation in Medicine


Objectives l.jpg
Objectives

  • History of nuclear medicine

  • Benefits of Nuclear Medicine

  • Radiation Biology: interactions and effects

  • Diagnostic and Therapeutic Applications

  • Common Nuclear Medicine procedures


Overview l.jpg
Overview

  • Over 20 million procedures annually in US

  • Provides information unobtainable by other means

  • Useful for diagnosis and therapy

  • Sensitive, can detect many diseases at early stages

  • Less expensive than exploratory surgery

  • Based on ionizing radiation

  • Allows evaluation of physiologic function

  • Non-invasive, painless


Slide4 l.jpg

Historical Perspectives

  • 1896 X radiation discovered by Roentgen

  • 1896 Ionizing radiation discovered by Becquerel

  • 1900 Quantum Hypothesis - Planck

  • 1905 Special Theory of Relativity - Einstein

  • Continuing interest led to development of the field of Radiation Physics

  • Advances allowed for the creation of isotopes

    • varying physical characteristics

  • 1951 FDA approves I131 as radiopharmaceutical


How it works l.jpg

How it Works

Physical and Biological Considerations


Basic concept l.jpg
Basic Concept

  • Radiation is used to image or treat disease

    • external or internal source

  • Radiopharmaceutical is selected

    • physical characteristics of radiation source

    • biological characteristics of target cells

  • Radiation dose is administered to patient

    • inhalation, ingestion, injection, or external beam

  • Imaging is possible due to radiation energy

  • Therapy is possible due to radiotoxicity


Radiation physical characteristics l.jpg
Radiation Physical Characteristics

  • Nucleus

    • protons, neutrons

    • neutrons “stabilize” nucleus

  • Nuclear instability

    • increasing nuclear mass => decreasing nuclear stability

  • Decay to stable state through loss of mass

    • as energy (E=mc2) in the form of photons

    • as particles: alpha, beta, positron, neutron

  • Radiological half-life

    • time to decay to one-half original activity


Radiation decay products l.jpg
RadiationDecay Products

  • Alpha particle

    • high mass (2 neutron, 2 protons)

    • low velocity

  • Beta

    • low mass (electron)

    • intermediate energy

  • Gamma

    • very low mass (photon, wave-particle duality)

    • energetic

  • Neutron

    • wide range of energies

    • activation


Biological effects tissue interaction l.jpg
Biological EffectsTissue Interaction

  • Ionizing Radiation Toxicity

    • disrupts cellular DNA

    • creates free radicals (peroxides)

  • Linear Energy Transfer (LET)

  • Tissue radiosensitivity

    • relative biological effect

    • uptake and elimination


Toxicity cellular effects l.jpg
ToxicityCellular Effects

  • Function of ionization density

  • DNA bonds

    • repair mechanism overwhelmed

    • increased mutations

    • loss of ability to replicate

  • Free radicals

    • destruction of cellular contents


Biological interactions linear energy transfer let l.jpg
Biological InteractionsLinear Energy Transfer (LET)

  • Measure of ionization density

    • ionizations/unit volume

  • Energy (eV) deposited per micrometer of travel

    • Low LET: gamma, beta, x-radiation

    • High LET: alpha, neutron radiation


Linear energy transfer l.jpg
Linear Energy Transfer

FIGURE 4.3 Penetrating power of alpha and beta particles. SOURCE: Courtesy of Joseph Jurcic, Memorial Sloan-Kettering Cancer Center.


Biological interactions relative biological effect l.jpg
Biological Interactions Relative Biological Effect

  • Relative Biological Effect

    • relative effectiveness of different emissions in producing a biological effect

  • Quality factor (Q)

    • tissue effects of different types of radiation

      • photon, beta = 1

      • neutron = 10

      • alpha = 20


Biological interactions tissue radiosensitivity l.jpg
Biological Interactions Tissue Radiosensitivity

  • Metabolic Rate

    • correlates with nutrient uptake rate

  • Tissue-specific nutrients, configuration

  • Replication rate

    • correlates with nutrient uptake rate

  • Elimination rate

    • biological half-life


Biological interactions uptake and elimination l.jpg
Biological Interactions Uptake and elimination

  • Nutrient/substrate uptake

    • attach nucliide to ligand

    • preferential uptake by target cells

      • Glucose in brain

  • Elimination

    • biological half-life

    • matabolism

    • physical half-life


Radiopharmacy selection of agent considerations l.jpg
RadiopharmacySelection of Agent: Considerations

  • High LET

    • high energy deposition in target cells

    • ionizations produced in target cells

  • Low LET

    • little energy absorbed per unit weight

    • few ionizations produced in tissue

  • Target cell specificity

    • uptake

  • Exposure to surrounding tissue

    • ALARA




Diagnostic modalities l.jpg
Diagnostic Modalities

  • Positron Emission Tomography (PET)

  • Single Photon Emission Computed Tomography (SPECT)

  • Radioimmunoassay (RIA)

  • Scintigraphy

  • Co-Registration

    • PET with MRI or CT


Diagnostic studies l.jpg
Diagnostic Studies

  • Renal function

  • Coronary artery perfusion and cardiac function

  • Lung scans for respiratory and blood flow problems

  • Inflammation and infection

  • Ortho - fractures, infection, arthritis and tumors

  • Cancer detection and localization

    • lymph node evaluation, metastases

  • GI bleed

  • Thyroid function

  • Cerebral perfusion and abnormalities (seizures, memory loss, TBI)


Diagnostic studies exposure risk l.jpg
Diagnostic StudiesExposure Risk

  • Low energy gamma and positron radiations

  • Low exposure (dose)

    • comparable to diagnostic x-ray studies

    • natural background radiation

  • Low risk

    • dose received is not harmful to the patient


Positron emission tomography l.jpg
Positron Emission Tomography

  • F18 FDG (fluorodeoxyglucose) typically used

    • weak positron emitter (low radiation dose)

  • Glucose analog

    • high uptake by brain, kidney, tumor, cardiac, and lung tissue

    • physiologic function

  • Excellent 3-D imaging

    • precise localization of tissue

    • monitoring therapeutic efficacy



Monitoring therapy esophageal tumor l.jpg
Monitoring Therapy Esophageal tumor

  • PET more sensitive than CT for monitoring therapy

  • Expanding role for PET

  • Society of Nuclear Medicine, Wieder et.al. 2005


Metastatic breast carcinoma l.jpg
Metastatic Breast Carcinoma

  • 27 year-old woman initially diagnosed with invasive ductal carcinoma by ultrasound guided biopsy. She underwent bilateral mastectomy, chemotherapy, and right-sided radiation


Scintigraphy compared with pet l.jpg
Scintigraphy compared with PET

  • 27 year-old woman with history of breast cancer


Case study l.jpg
Case Study

  • 49 year old man presents for staging after grossly complete excision of a high grade fibrosarcoma from the right groin 1.5 weeks earlier

  • Uneventful surgery

  • Progressively increasing pain at the surgical site following removal of a drain 4 days earlier


Post surgical abscess l.jpg
Post-surgical Abscess

  • 18F PET study


Pet scan availability l.jpg
PET Scan Availability

  • Increasing availabilty

    • over 1600 centers nationwide

    • http://petnetsolutions.com/zportal/portals/pat/find_a_pet_center/imagingcenter

  • Cost

    • $3 000 to $6 000

    • 3 hours for study

  • Advantages

    • metabolic scanning

  • Provider information

    • http://www.petscaninfo.com/zportal/portals/phys


Spect l.jpg
SPECT

  • Less expensive than PET

    • $1000 v $3000

  • Widely available

  • Commonly used for brain scans, perfusion studies

  • Sensitivity

    • cerebral ischemia 90% (v 20% CT) @ 8 hours

    • fracture 80% @ 24 hours, 95% @ 72 hours

    • seizure (ictal state) 81-93%

    • myocardial ischemia 90%


Cerebral ischemia sensitivity 90 l.jpg
Cerebral IschemiaSensitivity = 90%

Clin Nucl Med. 2006 Jul;31(7):376-8


Spect muga cardiac function and ef l.jpg
SPECT MUGA Cardiac Function and EF

  • Tc99m labeled rbc’s

  • Left ventricular hypertrophy with global hypokinesis

  • 47 years old with history of CAD


Spect muga cardiac function and ef33 l.jpg
SPECT MUGA Cardiac Function and EF

  • Tc99m labeled rbc’s

  • Left ventricular hypertrophy with global hypokinesis

  • 47 years old with history of CAD


Slide34 l.jpg

T-cell lymphoma

Emission from lateral thighs,

right triceps, and inguinal lymph nodes


Scintigraphy l.jpg
Scintigraphy

  • Molecular imaging

    • indicator of metabolic activity

    • “hot spots” where uptake is high

  • Low radiation exposure

    • Short half-life, low energy gamma radiation

  • Extensive application in many specialties

    • Orthopedics, Cardiology, Endocrinology, etc


Case study36 l.jpg
Case Study

X-ray of an 18-month-old boy unable to bear weight on his R leg s/p twisting injury x 2d


Bone scan at 7 days post injury l.jpg
Bone Scan at 7 days post-injury


Case study38 l.jpg
Case Study

18 yo. male with darkening urine, worsening muscle pain, and decreasing urine output over the past 3 days after one day of intense physical exercise


Slide39 l.jpg

Rhabdomyolisis

  • Elevated kidney uptake w/o bladder activity

  • Decreased activity in vastus medialis suggests necrosis


Pet ct co registration l.jpg
PET/CT Co-registration

  • Provides anatomical and physiological information



Therapeutic modalities l.jpg
Therapeutic Modalities

  • Brachytherapy

  • Ablation

  • Targeted Alpha Therapy

  • Gamma knife

  • External Beam

  • Boron Neutron Capture Therapy


Therapeutic applications examples l.jpg
Therapeutic ApplicationsExamples

  • Cancer Treatment

  • Tumor destruction

  • Palliation of pain

  • Marrow Transplants


Brachytherapy l.jpg
Brachytherapy

  • Radioactive “seeds” emplaced in surgically implanted tubes

  • Dose calculation by medical physicist

  • Tumour geometry determined through imaging modalities


Prostate cancer treatment l.jpg
Prostate Cancer Treatment

  • Tube placement geometry allows creation of interlocking radiation field around target

  • Field maximizes dose to target while minimizing collateral damage


Iodine ablation l.jpg
Iodine Ablation

  • Ingestion of radioactive cocktail I131

  • Dose delivered after surgical thyroidectomy

  • Patient becomes radioactive

  • Hospitalized until safe for general public


Targeted alpha therapy l.jpg
Targeted Alpha Therapy

  • Carrier molecule “tagged” with alpha emitter

    • monoclonal antibodies

  • Delivery of alpha-emitting isotopes to target

    • High LET

    • capable of killing in a range of 1 to 3 cells

  • Leukemia cells and small solid tumors

  • Myeloid leukemias, prostate cancer, and lymphoma treatments are under study


Monoclonal antibody radioactive source chelated to agent l.jpg
Monoclonal AntibodyRadioactive Source Chelated to Agent


Slide49 l.jpg
BNCT

  • Boron Neutron Capture Therapy

  • Boron delivered to target cells

  • Neutron irradiation => activiation of boron

  • 11Boron decay yields alpha particles

    • High LET of alpha deposits energy within 3 cell diameters

    • kills target while minimizing effect to surrounding tissue


Gamma knife l.jpg
Gamma Knife

  • Precise location and tumor geometry essential

  • Cobalt-60 source

    • high level of penetrating gamma rays

  • Two hundred one beams focused on target

  • Delivery controlled by shield

  • Frame emplaced to hold shield

  • Procedure lasts about 4 hours


Therapeutic benefits l.jpg
Therapeutic Benefits

  • Brain tumors

    • (benign and malignant) brain tumors

    • metastatic lesions

    • allows treatment in hard-to-access (inoperable) areas of the brain.

  • Arteriovenous malformations (AVMs)

    • in brain can cause severe bleeding, headaches or seizures

  • Trigeminal neuralgia

    • create a lesion on the nerve blocking its pain signals

  • Acoustic neuromas

    • lower risk of deafness or loss of facial movement than with conventional surgery.

  • Pituitary tumors


Gamma knife52 l.jpg
Gamma Knife

  • Concept: to create an interlocking field of gamma radiation emissions centered on the target

  • Tumour geometry is determined via imaging modality



ad