For easier understanding, we have compiled a glossary of key terms:
Absorbed Dose
The absorbed dose is the quotient of the mean energy that is deposited in matter by ionising radiation in a volume element and the mass of matter in that volume element. The unit of absorbed dose is the Gray, i.e. 1 Gy = 1 J/kg.
Carbon Ions
Carbon ions are carbon atoms in which at least one electron or even all six electrons have been removed. Just as protons, carbon ions are medically used in the context of ion beam therapy.
Chemotherapy
Chemotherapy is a drug treatment of cancer, where substances are used, which exert their effects in a very targeted way on certain disease-causing microorganisms or cells and kill them or inhibit their growth. In treatment of malignant tumours, most of these substances affect the rapid proliferative potential of tumour cells, since these respond more sensitivly than normal cells to disturbances in cell division. However, on healthy cells with similar proliferative potential they have a similar effect, thus permitting side effects such as blood disorders or diarrhea.
Dosimetry
Dosimetry is a measuring technique using dosimeters for the determination of dose created by ionising radiation in matter.
Equivalent Dose
An equivalent dose is defined as the product of absorbed dose and a factor, dependent from type and energy of the radiation, i.e. the quality factor. The value of this factor is determined by biological insights and ranges from 1 for photons to 20 for heavy nuclei. The equivalent dose is measured in Sievert, ie 1 Sv = 1 J/kg, due to the fact that the quality factor is dimensionless.
Experimental Physics
Experimental physics tries to gain qualitative and quantitative insights of physical processes with the help of planned scientific tests that are carried out on the exact same terms of reproducible and interference-avoiding conditions. An important prerequisite of experimental physics is the repeatability of the experiments. This alone can guarantee objectivity of statements. On the one hand, experimental physics acts as an engine for theoretical physics, given the fact that surprising experimental results must be integrated in the intellectual edifice of physics, on the other hand, experimental physics is driven by theoretical physics, as new theories must always be tested on the nature in order to develop their obviousness,
borders and relationships.
Helium
Helium is the second lightest chemical element in the periodic table of the elements after hydrogen and is among the noble gases. It is a colourless, odourless, tasteless gas and liquifies only close to the absolute zero point.
Horizontal Beam Line
A horizontal beam is defined as a fixed beam line, reaching horizontally into the irradiation room at a certain height. In order to gain radiation fields from different directions the area targeted for irradiation must be moved around such a horizontal beam line.
Immunotherapy
Immunotherapy is a collective term for very different treatment approaches, with which the activity of the immune system can be influenced. In oncology, we distinguish between the different therapeutic approaches of active and passive immunisation. In active immunisation, the patient receives administered substances to induce an immune response in their immune system. The immune response thereby ideally leads to the death of tumour cells, or at least to a delayed tumour growth. In contrast, in passive immunisation the patient receives antibodies or antibody fragments. These selectively bind to tumour cells and thus lead to their demise. In adoptive immunotherapy the patients leukocytes are removed and cultured ex vivo to be re-injected.
Indication
The medical term indication describes the medical procedure that should be used for a certain disease.
Ions
An ion is an electrically charged atom or molecule. In the neutral state atoms or molecules have exactly as many electrons as protons. The electric charge, and thus the ion, is created when an atom or molecule has either more ore less electrons compared to the neutral condition. Ions are positively charged in electron deficiency and negatively charged in excess of electrons. Because of the electrical charge of ions through ion sources and particle accelerators they can be bundled and accelerated to high speeds in an ion beam.
Ion Beams
Ion beams (particles or particle beams) are definded as rapidly moving ions designated with non-zero rest mass. When passing through matter, these ions transfer their energy in terms of scattering processes until the kinetic energy of the ions finally sinks to the value of thermal energy.
The way the particles cover in order to get there is called range. The range depends on the particle type, initial energy and of the material the particles pass. The energy transfer per distance unit on the matter also is determinded by the particle type, the material and the instantaneous energy. Mostly, the energy transfer increases per distance unit during the path traveled by the particle. The curve that describes this is called Bragg curve, named after William Henry Bragg. Shortly before the end of the trail the energy transfer achieves a maximum and then drops abruptly to zero. This is used in ion beam therapy, in order to mainly harm the tumour and spare the surrounding tissue.
Ion Beam Therapy
Ion therapy (particle therapy) is a part of the external radiotherapy where not photon and electron beams but ion beams are used. Compared to conventional radiotherapy, the energy output of the ion beams can be controlled much more effectively. As a result, the unwanted dose in healthy tissue can be reduced which leads to a reduction of treatment-related side effects.
Ionising Radiation
Ionising radiation is a term for any particle radiation or electromagnetic radiation, which can remove electrons from atoms or molecules, so that positively charged ions or molecular residues remain (ionisation). In direct ionising radiation, the energy transfer takes place by the Coulomb interaction, i.e. the invading primary charged electrons, protons, etc. give off their energy to the electrons of the absorber medium. Indirectly ionising radiation, however, is produced by electrically neutral particles like photons and neutrons, the energy release is a two-stage process: firstly, charged particles (electrons, protons, etc.) are released from the atoms of the absorbing medium and then these charged secondary particles – just like the direct ionising radiation – give their energy to the electrons of the absorber medium.
Light Ions
In ion beam therapy particles of with a low mass number such as protons or helium ions are called light ions. Heavy ions are, for example, carbon or oxygen ions.
Linac
Linac is the abbreviation for linear accelerator. In contrast to circular accelerators in a linear accelerator, the particles to be accelerated pass the accelerator unit only once and no magnetic fields deflecting the particle beam are necessary. Therefore, no synchrotron radiation is generated.
Local Recurrence
In general, recurrence is the relapse of a disease after treatment. A local recurrence in the treatment of cancer refers to the re-appearance of a tumour at the source.
Medical Radiation Physics
The medical radiation physics is concerned with the use of radiation beam therapy and/or diagnosing diseases. These include inter alia dosimetry, treatment planning and the use of radiation beam therapy and diagnostic imaging.
Non-Ionising Radiation
The non-ionising radiation is electromagnetic radiation whose energy is insufficient to ionise an atom or molecule and can thus cause no changes in the cells of living organisms. Non-ionising radiation includes for example electric and magnetic fields, heat radiation or light.
Photons
Figuratively speaking, photons are, what electromagnetic radiation is made of. Therefore, the term “light particles” is used quite frequently. Any electromagnetic radiation, from radio waves to gamma radiation, is quantised into photons. This means that the smallest amount of electromagnetic radiation of any frequency is a photon. Photons have an infinite natural life, but can be produced or destroyed in a variety of physical processes. A photon is never at rest but always moves at the speed of light. Thus, it can have no rest mass.
Physical Selectivity
Physical selectivity is defined as the feature of a radiation quality that shows the most steep dose gradients between the area to be irradiated and to the surrounding tissues (organs) that need to be spared.
Protons
The proton (hydrogen ion) is a hydrogen atom ionised by the loss of an electron. It belongs, with the neutron and the electron, to the building blocks of which matter consists. Like carbon ions, protons are used in medicine foron beam therapy.
Proton Gantry
A proton gantry is a rotating device that allows to irradiate a tumour from different directions with a proton beam. It is therefore not necessary that the target area to be irradiated is moved.
Radiation Biology
Radiation biology, as an interdisciplinary science, studies the biological effects of ionising and non ionising radiation. It works with molecular, cytogenetic and cytometric methods in different organisms and cell systems. At DNA level, radiation-induced mutagenesis and its repair is being investigated.
Radiation Therapy
Radiation beam therapy (radiotherapy, radiation oncology) deals with the medical use of ionising radiation on humans and animals to cure disease or retard its progression. As ionising, high-energy beams mainly gamma rays, X-rays and electrons are used. In recent years, plants for treatment with neutrons, protons, and carbon ions were established. Radiation beam therapy involves the treatment of benign and malignant diseases.
Beam Parameters
The beam parameters characterise an accelerated ion beam. Typical beam parameters are for example particle type, energy, intensity or size.
Secondary Malignancies
Malignancy is a synonym for cancer or a cancer tumour and a medical term denoting a malignant (cancerous) tumour, i.e. malignant neotissue formation. Tumours appearing after treatment are called secondary malignancies.
Secondary Radiation
Radiation, generated by the passage of ionising radiation through matter is called secondary radiation.
In ion beam therapy, for example the nuclear reactions with the nuclei of the tissue produce high-energy secondary particles such as neutrons, protons, deuterons, and helium nuclei.
Synchrotron
The synchrotron is a circular particle accelerator that can accelerate charged fundamental particles or ions to very high (relativistic) velocities. For acceleration, suitably synchronised high-frequency alternating electric field (microwaves) is used. In order to keep the particles on a closed track, the magnetic fields of the electromagnets in use need to be readjusted depending on the achieved energy of the particles. To avoid the loss of particles by collisions with gas particles, the particle trajectory lies in a complete vacuum tube system providing an ultra high vacuum.
Tumour Board
A tumour board is a multidisciplinary tumour committee, where experts from various clinical areas such as surgery, radiotherapy, radiology and oncology meet at regular intervals to determine the therapeutic method for patients with tumours. Through this interdisciplinary review of individual cases, each patient can obtain tailored treatment according to the latest findings of medical science.
