Proton Radiography- a Promising Tool For Imaging Tumours

Prof.Dr Abhinandan Ballary 

January 25, 2023,

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Abstract

Proton radiography is a type of imaging technique that  uses  protons,  rather  than  x-rays  or other forms of ionizing radiation, to create images of internal structures in the body. The protons are typically generated by a particle accelerator, such as a cyclotron, and are then directed at the area of the body being imaged. The protons interact with the tissue in a way that allows scientists to create images of internal structures, such as bones, blood vessels, and tumors.

Proton radiography has several advantages over other imaging techniques. For example, pro- tons can be precisely aimed at a specific area of the body, allowing for more precise images and minimizing exposure to surrounding tissue. This makes proton radiography a useful tool for imag- ing tumors and other abnormalities that are close to sensitive structures like the brainstem or spinal cord. Additionally, because protons do not ionize the tissue as much as x-rays do, proton radiography is less likely to cause long-term damage to healthy tissue.

Proton radiography is still considered as a research tool, it’s not yet widely available, and it is typically only used in specialized medical centers.

1) Introduction

Proton Radiography: A Promising  New  Tool  for  Imaging  Tumors”  is  a  recent  article  published  in the journal of Medical Physics, which discusses the potential of proton radiography as a new imaging technique for cancer diagnosis and treatment. The article describes the basic principles of proton radiography and its advantages over traditional imaging techniques such as X-ray and CT. It also discusses the current state of proton radiography research and its potential applications in the clinical setting, particularly in the imaging and treatment of tumors. The article concludes by highlighting the ongoing challenges and future directions in the field of proton radiography, including the need for further research to improve image quality and reduce radiation dose, as well as the development of new imaging technologies to enhance the capabilities of proton radiography.

2) PROTON  RADIOGRAPHY  :  SOME  INFORMATION

2.1) HISTORY

The history of proton radiography can be traced back to the early days of proton therapy, a type of radiation therapy that uses protons to treat cancer. In the 1940s and 1950s, scientists first began experimenting with using protons to treat cancer, and by the 1960s, the first proton therapy treatments were being performed at research centers around the world.

However, the ability to image internal structures using protons was limited at that time, and it wasn’t until the late 20th century that the technology advanced enough to allow for the creation of proton radiography images. In the 1990s, researchers began experimenting with using protons to create images, and by the early 2000s, the first proton radiography images were being created at research centers around the world.

In recent years, there has been an increased interest in proton radiography as a new imaging technique.  The development of new imaging detectors that are more sensitive to protons, as well as the creation of new image reconstruction algorithms, has made it possible to create more detailed and accurate proton radiography images.

The first proton radiography images were taken using a pencil-beam scanning technique, which is still widely used today. However, more recent developments include the use of imaging techniques like the spot-scanning technique, which allows for more precise and accurate images

2.2) RELATION WITH GOD PARTICLE

The ”God particle” is a nickname for the Higgs boson,  a subatomic particle that is  believed to give other particles mass. The nickname was coined by physicist Leon Lederman in his book ”The God Particle: If the Universe is the Answer, What is the Question?”

The Higgs boson was first proposed in the 1960s by physicist Peter Higgs and others as a way to explain why certain particles have mass.   According to the Standard Model of particle physics,  the Higgs boson is responsible for giving mass to other particles through its associated Higgs field.  The Higgs boson is unique in that it has no spin and is not affected by the strong or weak nuclear forces, the two other fundamental forces of nature.

The Higgs boson was detected for the first time in 2012 by the Large Hadron Collider (LHC) at CERN, the European Organization for Nuclear Research. The discovery of the Higgs boson was a major breakthrough in our understanding of the universe and is considered one of the greatest achievements in science in the 21st century.

The Higgs boson is also considered as an important step towards understanding the origin of mass in the universe and the process of electroweak symmetry breaking, which is a theory that explains why the weak force and the electromagnetic force are different.

The relationship between proton radiography and the Higgs boson, also known as the ”God particle,” is that they both involve the study of subatomic particles, but they are used for different purposes.

Proton radiography is a type of imaging technique that uses protons to create images of internal structures in the body. The protons are directed at the area of the body being imaged and interact with the tissue to create images of internal structures such as bones, blood vessels and tumors.

2.3) HOW PROTON RADIOGRAPHY WORKS MATHEMATICALLY

Proton radiography works by using protons to create images of internal structures in the body. The protons are typically generated by a particle accelerator, such as a cyclotron, and are then directed at the area of the body being imaged.  The protons interact with the tissue in a way that allows scientists to create images of internal structures.

Mathematically, proton radiography uses the principles of physics, specifically the principles of proton interactions with matter, to create images. The protons are directed at the body and as they pass through the tissue, they interact with the atoms and molecules in the tissue, losing energy in the process. This energy loss is known as the ”Bragg peak,” and it occurs at a specific depth in the tissue, depending on the energy of the protons.

The energy loss of the protons can be modeled using the Bethe-Bloch equation, which describes the energy loss of charged particles as they pass through matter. The Bethe-Bloch equation takes into account the density, atomic number, and energy of the protons and the target material.

In proton radiography, the protons are directed at the body at different angles and energies, which allows the creation of multiple images at different depths in the tissue. These images can then be combined to create a 3D image of the internal structure of the body.

In addition to the mathematical modeling, proton radiography also uses computational methods to reconstruct the images, such as tomographic reconstruction algorithms such as filtered back projection (FBP) and iterative reconstruction algorithms such as the algebraic reconstruction technique (ART) and the maximum likelihood expectation maximization (MLEM) algorithm. These algorithms take the 2D projections of the protons and use mathematical techniques to create a 3D image of the internal structure of the body.

2.4) RECENT DEVELOPMENTS

Proton radiography is a relatively new technology and continues to be developed and refined. Some recent developments in the field include:

  1. Improved imaging: Researchers are working on ways to improve the resolution and accuracy of proton radiography images. This includes developing new image reconstruction algorithms, as well as using new imaging detectors that are more sensitive to protons.
    1. Reduced radiation dose: One of the advantages of proton radiography is that it delivers a lower radiation dose than traditional x-ray imaging. However, researchers are still working on ways to further reduce the radiation dose to make it even safer for patients.
    2. Adaptive proton therapy: Proton radiography is being used to plan and guide proton therapy, a type of radiation therapy that uses protons to treat cancer. Adaptive proton therapy is a new technique that uses real-time imaging during treatment to adjust the proton beam in response to changes in the patient’s anatomy.
    3. Dual-energy proton radiography: Dual-energy proton radiography is a new technique that uses two different energy levels of protons to create images. This allows for the creation of images that can better differentiate between different types of tissue.
    1. Combining proton radiography with other imaging modalities: Researchers are exploring ways to combine proton radiography with other imaging modalities, such as MRI or CT, to provide more detailed and accurate images of internal structures.

It is worth noting that proton radiography is still considered as a research tool, it’s not yet widely available, and it is typically only used in specialized medical centers.

3) AS AN END: WHAT’S NEXT FOR PROTON RADIOG- RAPHY

Proton radiography is still a relatively new technology and there is ongoing research to improve its capabilities and make it more widely available. Some areas of focus for future development include:

  1. Improving image quality: Researchers are working on ways to improve the resolution and accu- racy of proton radiography images. This includes developing new image reconstruction algorithms and using new imaging detectors that are more sensitive to protons.
  2. Reducing radiation dose: One of the advantages of proton radiography is that it delivers a lower radiation dose than traditional x-ray imaging. However, researchers are still working on ways to further reduce the radiation dose to make it even safer for patients.
  3. Developing new proton therapy techniques: Proton radiography is being used to plan and guide proton therapy, a type of radiation therapy that uses protons to treat cancer. Researchers are working on new proton therapy techniques that use real-time imaging during treatment to adjust the proton beam in response to changes in the patient’s anatomy.
  4. Making proton radiography more widely available: Currently, proton radiography is only avail- able at a few specialized medical centers. Researchers are working to make the technology more widely available by developing new and more affordable proton accelerators.

It is worth noting that proton radiography is a complex and expensive technology, making it difficult to implement on large scale and it’s not yet widely available for general use. However, with the ongoing research and development, it is expected that proton radiography will become more widely available in the future, and will be a valuable tool for cancer diagnosis and treatment