Chapter 14 -- Medical Applications of Nuclear Technology

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Chapter 14 -- Medical Applications of Nuclear Technology

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Chapter 14 -- Medical Applications of Nuclear Technology

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Xiaodong He

Radiotherapy Center

Shanghai Pulmonary Hospital

Just after the moment of discovery of X rays, the importance of X rays in medical diagnosis was immediately apparent , and within months of its discovery, the bactericidal action of X rays and their ability to destroy tumors were revealed.

- Today, both diagnostic and therapeutic medicine as well as medical research depend critically on many increasingly sophisticated applications of nuclear radiation and radioisotopes.

Medical Applications of Nuclear Technology

Radiation Oncology

Nuclear

medicine

Radiation

Image

+

NMR

Medical Applications of Nuclear Technology are constituted by three parts above.

in vitro

RadioimmunoassayRIA

Camera Bone Scanning

Single Photon Emission Computerized

Tomography SPECT

Positron Emission Tomography

PET/CT

Radionuclide Therapy

Tumor, hyperthyroidism,etc.

Radionuclide analysis

in vitro + in vivo

According to the radioactive isotope analysis results of the Oak Ridge() lab:

In one year, 98% of the atoms of organism (human body) is replaced.

The body does not have a constant material.

And, in certain time the materials inside body are to produce thousands of times biological chemical reactions every second.

RIA as a kind of technology take the both advantages of accuracy and sensitivity of the radioactive isotope measurement and the specificity of the reaction of antigen and antibody.

It is a new in vitro technology for ultra trace (10-9~10-15g) material detection.

(10-9~10-15g)

Broadly, all the assay technologies via immune reactions by antigen and antibody which tagged by radioactive isotopescan be called RIA

So far has development to the fifth generation of RIA technology. It is characterised by the combination of magnetic particles and RIA or IRMA (immunoradiometric assay) .

PET/CT is a perfect fusing of PET and CT.

It can Provide detailed lesion function and metabolic information of moleculars by PET , and in the same time, provide the accurate lesion anatomic localization by CT.

It is characterised by sensitivity, accuration, specific and accurate location.

It is extensive used in radiotherapy, and also be called the high-tech coronal of Modern medicine.

The clinicalimaging process of PET is as followes:

a. Mark the radioactive isotopes which can emit positrons (such as F-18) to compounds which be gonna to participate in tissue blood flow, or in metabolic process.

b. Inject the tagged compounds into human body.

c. Theemission positron from radio-isotope can shift 1 mm in human body, and then combined with an electron in tissues and annihilate to produce two equal energy (511 KeV) and opposite photons.

It was recognized that detection of these photons, using the property that they are emitted simultaneously in opposite directions, would permit description, in three dimensions, of the distribution of the radionuclides in the body.

PET imaging of an object surrounded by a ring of detectors. Annihilation photons aare recorded by detectors on opposite sides of the ring,

the relative intensities allow determination of the mass thickness of the distances L1 and L2 in the patient through which these photons travel.

d. Annihilation photons leaving the body are detected by an array of detectors that surround the patient.

Events are recorded only when two detectors each detect an annihilation photon simultaneously, i.e., within 10 to 25 ns of each other. Events separated further in time are not recorded.

The line joining the two recording detectors is a line of response (LOR) along which the annihilation photons have traveled and on which the positron decay occurred.

This coincident detection technique allows a determination of the direction of the annihilation photons without the physical collimation needed in SPECT. For this reason coincident detection is often called electronic collimation.

PMT(Photo Multiplier Tube)

BGO (Bismuth Germanium Oxide

X ray Radiography, and DSA

Digital subtraction angiography

Computed Tomography CT

Magnetic Resonance Imaging NMR

Function NMRNMR spectrum analysation

4D fast CT and 4D fastNMR

- Convolution

h(t)e(t)y(t)

- tF

- Xhfghfg

- Fourier transformation
- /
- Two features
1. ,,

2. ,.,

- Laplace transformation

fourierlaplace

fourierfourierj

- Zlaplacez=esTT=T
- ZZ

- Question 1
- What is the main difference between fourier transformation and laplace transformation ?
main differencelaplace transformation is in whole complex planeand fourier transformation is just in imaginary axis.

- Question 2
- What is the physical and mathematical significance of laplace transformation?
physical significance: It establishes the relationship between the time domain and complex frequency domain.

mathematical significance: Converts differential equation to Algebraic equation, so as to simplify the calculation.

- ,
E = h

radio frequency pulse, RF

- Quantum mechanics
- Fourier transformation

Teletherapy

Brachytherapy

P, C

Teletherapy

X rays

Electrons

Elements used in teleradiotherapy

4DRT

CRT

IMRT

Teletherapy

Techniques used in teleradiotherapy

Iodine

BNCT

boron neutron

capture therapy

Ir-192

Cobalt-60

Brachytherapy

Elements used in brachytherapy

(125)I implantation

Brachytherapy

Brachytherapy

After loading

radiotherapy

Intracavity afterloading radiotherapy

Techniques applied in brachyradiotherapy

Seeds implant

Interstitial implant

brachytherapy

After-loading Intracavitary unit

A2cm

2cm

BA3cm

RT is a clinical subject of treating cancers by applying the theories and means of high energy rays to irradiate tumor targets.

What is Radiation ?

The most frequently used elements in RT

Candidate particles

Why RT can cure cancer disease--

1. RT is based on ionizing radiation

2. Ionization can inducetraumainjury

ionization

lethal damage

SSB

DSB

()

sublethal damage

potential lethal damage

3. Some type of cancer more sensitive to ionization irradiation than normal cells (sigmoid curves)

tumor

Normal tissue

More separating the curves in dose is,

more higher the curable probability be.

The role of RT in tumor treatment

Out of control

Till now, surgery, RT and chemotherapy are the major three ways to treat cancers. Nearly 2/3 of cancer patients need RT.

But radiotherapy has no good response for some patients, the main reason is that the 10%- 50 % of hypoxic cells in solid tumors have low response to radiotherapy

treatment

follow up

TPS

Virtual simulation and image fusion

CT SCAN

PET/CT MRI

To localization

Medical evaluation

(include pathologyphysicallab test, image)

Portal verification

QA

Simplified Radiotherapy Treatment Flow

Radiotherapy includes four branches:

1. Radiation Oncology

2. Radiation Physics

3. Radiobiology

4. Radiation Technology

A.Some important concepts

1. Liner Energy Transfer.

LET for short

E

LET =

KeV/

X

2. Ionization induced Direct and Indirect effects

Direct Directly act on target molecules

( Break DNA double strands )

: DNA

IndirectAffect target molecules via ionized

& excitated water molecules H2O

3. Oxygen Enhancement Ratio . OER

D0(dose for killing hypoxic cells)

OER =

D0 (dose for killing aerobic cells)

4. Relative Biological Effect . RBE

Doses which create a certain bio-effect by one standard ray

RBE =

Doses which create the same bio-effect by another ray

5. The characteristic of high LET rays

LET

a. There is a Bragg Peak

b. RBE OER

c. Direct effects is major

Cell phase independent

(Only for high LET)

6Absorbed Dose

D = Eab / m

Eab is absorbed energym is mass

7Kerma

Kinetic energy released per unit mass

K = dEtr / dm

It applies to indirect ionizing radiation

It is differ from the Karma in Buddhism.

8Cema ()

Converted energy per unit mass

It applies to direct ionizing radiation

dEc dm

- Question 3
Please describe the definitions and formulasof concepts Cema & Kerma?

9The relative dominant area of three main effects of photon-media interactions

These three effects are other than three actions, so called electromagnetic action,

weak action,

strong action.

Photoelectric effect

104Rconcept in RT

Cells be irradiated will experience four occurrences which named 4R.

4R --- Repair

Regeneration

Redistribution

Reoxygenation

- What is 4R in radiobiology?

5

host

servant

servant

Position verification

Irradiation techniques

Dose verification

If you cant see it , you cant hit it

If you cant hit it, you cant cure it

Historical Review

Experimental aspects

Theoretical aspects

Historical review

1. Experimental Discovery

1.1 In 1895, Roentgen discovered X rays

In 1901, He won the first Nobel Prize

1.2 In 1896, Becquerel discovered radioactive element of uranium

1.3 In July 1898, Madame Curie and her husband got a great success that they discovered the radioactive element, polonium, which Marie named after Poland.

1.4 The discoveries of rays

Rutherfords atomic model (1911)

Historical review

2. Theoretic Discovery

---Full of seminal ideas

- layer of structure

D~/mc

10-14m

(10fm)

Nucleus

10-10m

Atom

10-15m

(fm)

Nucleon

10-18m

quark

Wave-Particle Duality, Probbility, Entanglement

Schdinger- equation (introduce operator & complex number)

Klein-Gordon- equation

Dirac- equation (import spin matrix & Quaternions )

E i/t, P -i/r

E=p2/2m

E2=p2c2+m2c4

E=(p2+m2)1/2

=pc+mc2

High energy particles belong to

Relative territory.

~

The relative particles should suffice 1. Lorentz-transform invariance; 2. Curved space time.

Q+L

Particles

Nucleus

For particles, the criteria to distinguish

whether it is a relative particle or not is:

There are three types of quantum field theories

In 1934Pauliand Weisskopf pointed outthat just like Maxwell equation, K-G equation as well as Dirac equation are all the field equations.

K-Gs is for scalar field, which spin is most meson

Diracs is for rotary field(), which spin is

Maxwells is for vector field, which spin is photon

*

*

43/2 1/21

c. The Revolution in Radiotherapy

LETRBE(1.0)LETRBE(2.0)LETRBE20keV/mLETOER160keV/mRBEOER1LETRBED0()RBERBE

Electron

beam

How to treat moving target?

Movement and deformation

RPM Real-time Position Management

Respirationsynchronised imaging and treatment

The Real-time Position Management (RPM) system is a non-invasive, video based system that allows for clean imaging and treatment of lung, breast, and upper abdominal sites.

The RPM system is accurate, easy to use and fast. It is comfortable for the patient and accommodates both breath hold and free breathing protocols.

4D real time tracing system

4D Tx delivery Visualization:

Internal magnetic marker displacement (Calypso)

Calypso system: response

Next step after RPM

Thank you for your kind attention !