Chapter 14 -- Medical Applications of Nuclear Technology. Xiaodong He Radiotherapy Center Shanghai Pulmonary Hospit al.
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.
Medical Applications of Nuclear Technology
Medical Applications of Nuclear Technology are constituted by three parts above.
Camera Bone Scanning
Single Photon Emission Computerized
Positron Emission Tomography
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.
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
main differencelaplace transformation is in whole complex planeand fourier transformation is just in imaginary axis.
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
Elements used in teleradiotherapy
Techniques used in teleradiotherapy
Elements used in brachytherapy
Intracavity afterloading radiotherapy
Techniques applied in brachyradiotherapy
After-loading Intracavitary unit
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
Why RT can cure cancer disease--
1. RT is based on ionizing radiation
2. Ionization can inducetraumainjury
potential lethal damage
3. Some type of cancer more sensitive to ionization irradiation than normal cells (sigmoid curves)
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
Virtual simulation and image fusion
(include pathologyphysicallab test, image)
Simplified Radiotherapy Treatment Flow
Radiotherapy includes four branches:
1. Radiation Oncology
2. Radiation Physics
4. Radiation Technology
A.Some important concepts
1. Liner Energy Transfer.
LET for short
2. Ionization induced Direct and Indirect effects
Direct Directly act on target molecules
( Break DNA double strands )
IndirectAffect target molecules via ionized
& excitated water molecules H2O
3. Oxygen Enhancement Ratio . OER
D0(dose for killing hypoxic cells)
D0 (dose for killing aerobic cells)
4. Relative Biological Effect . RBE
Doses which create a certain bio-effect by one standard ray
Doses which create the same bio-effect by another ray
5. The characteristic of high LET rays
a. There is a Bragg Peak
b. RBE OER
c. Direct effects is major
Cell phase independent
(Only for high LET)
D = Eab / m
Eab is absorbed energym is mass
Kinetic energy released per unit mass
K = dEtr / dm
It applies to indirect ionizing radiation
It is differ from the Karma in Buddhism.
Converted energy per unit mass
It applies to direct ionizing radiation
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,
104Rconcept in RT
Cells be irradiated will experience four occurrences which named 4R.
4R --- Repair
If you cant see it , you cant hit it
If you cant hit it, you cant cure it
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)
2. Theoretic Discovery
---Full of seminal ideas
Wave-Particle Duality, Probbility, Entanglement
Schdinger- equation (introduce operator & complex number)
Dirac- equation (import spin matrix & Quaternions )
E i/t, P -i/r
High energy particles belong to
The relative particles should suffice 1. Lorentz-transform invariance; 2. Curved space time.
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
c. The Revolution in Radiotherapy
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 !