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Medical Physics

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Barry Heffernan

on 12 February 2014

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Transcript of Medical Physics

Medical Physics
As usual with these module we are attempting to cover a very advanced and vast topics in a few lab sessions. To try to achieve this the module will be roughly divided as follows:
What is Medical Physics?
Medical Physics is generally speaking the application of physics concepts, theories and methods to medicine/healthcare.
More Robust Definition
Medical physics is a branch of physics that includes applications of physics in medicine. Since the turn of the 20th century, radiation has been a part of medicine. The medical applications of x-rays and have given rise to the discipline of Medical Physics.
Its primary focus is physics as applied to radiation therapy, medical imaging, radiation biology and radiation protection, though it is also involved in other areas of medicine including bio-electricity, bio-mechanics and medical instruments.
Week 1 - Introduction to Medical Physics, medical physicists and some applications.
Week 2 - A more detailed look at radiation and how it is used in medicine.
Week 3 - Modern Imaging techniques (CT, PET, MRI)
Irradiation of the breast
Ionization Measurements
First telecobalt machine

Son of Iridium-192 Ch.Fisher, B.Pierquin
The scanner
"Gray" Unit
Development of equipment imaging MN
The beginning of Medical Physics
Discovery of natural
X-ray machine
Discovery of polonium and radium
Brachytherapy Radium
Discovery of X-rays
Wilhelm Conrad
The first application of X-ray medicine is that of fluoroscopy and radiography.
X-ray of the hand of Anna Bertha Röntgen:
Henri Becquerel
which the high voltage generator is operated by hand!
First radiotherapy treatment of stomach tumor by
The first experience of gynecological brachytherapy radium.

Margaret Cleaves
Irradiation of the breast by Dr. Chicotot
Beginning of the dosimetry the photographic method (Kienböck)
Creation of the ICRU (International Commission for units radiation and measurement)
Creation of the
(International Commission on Protection Radiological)

Accept roentgen
Marie and Pierre Curie and the Discovery of Polonium and Radium
Saskatoon Cancer Clinic, Canada.
("Radiation Absorbed Dose") unit
Son of Iridium-192
Iodine-125 brachytherapy used in the USA
First prototype of computed tomography (CT)
gray (Gy)
defined in
replaced the rad in
(1 Gy = 100 rads)
Period of development technological and computer
Multimodality imaging in radiotherapy (CT, MRI, PET)
Accelerators with MLC
Dedicated accelerators
or robotic (Cyberknife), ...
innovative techniques
(IMRT, stereotactic,
IGRT, gating, RT
adaptive IMBT ..)
Proton, heavy ion
Development of algorithms for calculating dose calculation 3D

Medical Physicists
apply knowledge and methodology of science of physics to all aspects of medicine, to conduct research, develop or improve theories and address problems related to diagnosis, treatment, and rehabilitation of human disease. They are directly involved with patients and people with disabilities.

(Revised definition provided by International Organisation for Medical Physicists)
International Labour Organization (ILO)
(a) Conducting research into human disorders, illnesses and disabilities; investigating biophysical techniques associated with any branch of medicine.
(b) Conducting specialised examinations of patients and the disabled, improving patient care and clinical services, developing innovative imaging and non-imaging diagnostic procedures for specific medical applications.
(d) Ensuring the quality, safety testing and correct maintenance and operation of treatment
machines, x-ray equipment, radiation treatment planning computers; medical uses of
ultrasound, MRI, and infrared; and the correct delivery of prescribed radiation doses to
patients in radiation therapy;
(f) Calculating dose distributions and machine settings; design and fabrication of treatment aids and treatment-beam modifiers for individual patient treatments.
(h) Advising and consulting with physicians on the physical and radiobiological aspects of patients’ treatments, and the development of treatment plans in such applications as use of ionising radiation in diagnosis, therapy, treatment planning with externally delivered radiation as well as use of internally implanted radioactive sources given the state of technology
(j) Formulating radiation protection guides and procedures specific to hospital environment and other professional groups and organizations; conducting specialised measurements and producing protocols to minimise radiation exposure of patients, staff and the general public;
(c) Developing novel instrumentation and physiological measurement techniques, mathematical analysis and applications of computers in medicine in response to clinical need for patients, and aids to everyday living for the disabled;
(e) Ensuring the accuracy of treatment unit parameters and settings used for a patient’s treatment, including correct transfer of parameters between the simulator, treatment plan and the treatment unit, and periodic review of each patient’s chart.
(g) In-vivo measurement to verify the dose delivered to a patient; participation at patientdiscussion conferences.
(i) Planning, directing, conducting, and participating in supporting programs and remedial procedures to ensure effective and safe use of ionising and non-ionizing radiation and radio nuclides in human beings by physician specialist
(a) Conducting research into human disorders, illnesses and disabilities; investigating
biophysical techniques associated with any branch of medicine.
(radiation oncology)
Most medical physicists work in radiation therapy. Radiation therapy is the process of treating cancer by projecting high-energy radiation at targeted cancer cells to shrink and eliminate tumors. In this area, medical physicists work as part of an oncology team that implements treatment plan. Medical physicists review plans developed by dosimetrists and They verify that the treatment plans are safe and effective, based on their knowledge of physics and human biology.
Nuclear medicine is used for both imaging and treatment after patients have received small amounts of radioactive materials—called radiopharmaceuticals—whether orally, intravenously,Or by inhalation. In imaging, special cameras detect the radiopharmaceuticals and display information based on biological changes that occur when disease is present.In treatment, radiopharmaceuticals act specifically on the area being treated.
Nuclear Medicine
Medical physicists involved in patient diagnosis are concerned with technologies that produce images of the body’s internal structure. These technologies allow physicians to see abnormalities and to monitor various processes, such as blood flow. The medical physicist’s role is to ensure that such technologies are used both safely and effectively.
Diagnostic radiology
Brachytherapy (from the Greek word brachys, meaning "short-distance"), also known as internal radiotherapy, sealed source radiotherapy or endocurietherapy, is a form of radiotherapy where a radiation source is placed inside or next to the area requiring treatment.

Brachytherapy is commonly used as an effective treatment for cervical, prostate, breast, and skin cancer and can also be used to treat tumours in many other body sites.
Radiation dosimetry is the measurement and calculation of the radiation dose received by matter and tissue resulting from the exposure to indirect and direct ionizing radiation. It is a scientific sub-specialty in the fields of health physics and medical physics that is focused on the calculation and analysis of internal and external dose.
X-ray computed tomography (x-ray CT) is a technology that uses computer-processed x-rays to produce tomographic images (virtual 'slices') of specific areas of the scanned object, allowing the user to see what is inside it without cutting it open.

Digital geometry processing is used to generate a three-dimensional image of the inside of an object from a large series of two-dimensional radiographic images taken around a single axis of rotation.
Offline Resources
From IOP
Alpha Particles
Beta Particles
Alpha particles consist of two protons and two neutrons bound together into a particle identical to a helium nucleus.
They are generally produced in the process of alpha decay, but may also be produced in other ways.
Beta particles are high-energy, high-speed electrons or positrons emitted by certain types of radioactive nuclei such as potassium-40.
The beta particles emitted are a form of ionizing radiation also known as beta rays.
The production of beta particles is termed beta decay.
They are designated by the Greek letter beta (β). There are two forms of beta decay, β− and β+, which respectively give rise to the electron and the positron
Alpha particles are named after the first letter in the Greek alphabet, α. The symbol for the alpha particle is α or α2+. Because they are identical to helium nuclei, they are also sometimes written as He2+ or 42He2+
indicating a Helium ion with a +2 charge (missing its two electrons).
If the ion gains electrons from its environment, the alpha particle can be written as a normal (electrically neutral) Helium atom 42He.
We said that radiation is used in medical physics, electromagnetic radiation is a wave.
Sound is also used for ultrasound imaging which is an also a wave.
In a couple of simple experiments we call look at two fundamental properties of waves, Reflection and Refraction.
Learning Check
So what is Medical Physics?
Learning Check
How were x-rays discovered?
What is a CT scanner?
Name and explain two other important developments in medical physics.
Learning Check
Name three different forms of radiation.
Are all forms of radiation dangerous?
What is the difference between ionising and non-ionising radiation?

Learning Check
So what is a Medical Physicist?
Name three duties a medical physicist might have to perform.
Learning Check
Briefly explain what radiation therapy, diagnostic radiology and nuclear medicine are.
Plain X-Rays
and CT
Offline Resources
From IOP
Positron Emission Tomography
Offline Resources
From IOP
Magnetic Resonance Imaging
Offline Resources
From IOP
Gamma Camera
Offline Resources
From IOP
Pulse Oximeters
(IOP resource)
IOP resource
Full transcript