Chemistry Reference
In-Depth Information
Imaging-timeline
1895:- Physicist Wilhelm Conrad Röntgen publishes the rst medical image-the rst X-ray picture, showing the skeletal
composition of his wife's left hand. He was awarded the Nobel prize in 1901
1903:- Nobel prize awarded for discovery of radioactive elements-Marie curie, Pierre Curie as well as Antoine Henri Becquerel
X-ray
1890s-
1900s
1931:- Ernst Ruska and Max Kroll construct an electron microscope, the rst instrument to provide better
denition than a light microscope. (In 1986 Ruska is awarded half of the Nobel prize in physics.)
1932:- Frits Zernike invented the phase-constrast microscope that allowed for the study of colourless and transparent
biological materials such as cells for which he won the Nobel prize in physics in 1953.
Light/electron
microscope
1930s
1950s:- Prof. Ian Donald develops practical technology and applications for ultrasound as a diagnostic tool in obstetrics
and gynecology. This displays images on a screen of tissues or organs formed by the echoes of inaudible sound waves at
high frequencies.
1946:- Physicists Edward Purcell and Felix Bloch discover NMR-awarded Nobel prize in 1952
Ultrasound
/NMR
1940s-
1950s
1962:- First positron emission tomography transverse section instrument.
1974:- Michael Phelps develops the rst positron emission tomography camera and the rst whole-body system for human and
animal studies.
PET
1960s
1970s
1973:- Chemist Prof. Paul Lauterbur develops the rst magnetic resonance image (MRI) using used nuclear magnetic resonance data
and computer calculations of tomography. (2003-he shares the Nobel prize in physiology or medicine with Peter Mansels for their
pioneering MRI work.)
MRI
1970s
1972:- Engineer Godfrey Hounseld and Allan Cormack develop the computerised axial tomography scanner, or CAT scan. The device
combines many X-ray images to generate cross-sectional views as well as three-dimentional images of internal organs and structures.
1979:- They were awarded thr Nobel prize in physiology or medicine for their development of computer assisted tomography-CT scan
CT
Late
1970s
Advancement in multimodal imaging
Today
FIgure 1.3
An approximate timeline showing the development of the different imaging modalities [1-3].
Fluorodeoxyglucose
H OH
H
O
HO
H
HO
H
18
F
OH
H
FIgure 1.4
18
FDG, a typical contrast agent used in PET.
1.2
WhAt Is PosItron eMIssIon toMogrAPhy (Pet)?
Positron Emission Tomography (PET) is a nuclear medicine tomographic modality and one of the most sensitive methods
for quantitative measurement of physiologic processes
in vivo
[4]
.
This technique utilises positron-emitting radionuclides
and requires the use of radiotracers that decay and produce two 511 keV
γ
-rays resulting from the annihilation of a positron and
an electron. one of the most commonly used molecules is
18
F-labelled fluorodeoxyglucose (
18
FDG), which has radioactive
fluorine and is readily taken up by tumours (Figure 1.4) [5].
1.2.1
Basic Principles
In PET, a neutron-deficient isotope causes positron annihilation to produce two 511 keV
γ
-rays, which are simultaneously emitted
when a positron from a nuclear disintegration annihilates in tissue. PET imaging, unlike MrI, ultrasound, and optical imaging,
does not require any external sources for probing or excitation; instead, the source is generated from radioisotopes and emitted from
