Professional terms that may be encountered during radiation therapy
Adjuvant therapy (Adjuvant therapy)
There are usually three basic forms of treatment for tumors: surgery, radiation therapy, and chemotherapy. For different patients and specific conditions, one treatment modality will usually be the first choice. In some cases, in order to enhance the effect of the first treatment modality and reduce the possibility of tumor recurrence, one or two other modalities will be used to treat the tumor, which is called adjuvant therapy. Adjuvant therapy may be given before or after the first treatment, or in some cases, at the same time.
Applicator
A device that is placed on the patient’s body where the tumor is treated during brachytherapy and is used to mount and hold the radiation source.
Beam films/Port films/Beam-eye-views
A real-time photograph of each irradiation field projected on the patient’s treatment site while the patient is in the treatment position. The accuracy of the treatment site and the shape of the irradiated fields can be verified by comparing this photograph with the photographs taken during the simulated positioning or the digitally reconstructed images created by the computerized treatment planning system. This is a key quality control verification step in modern radiation therapy technology.
Biology therapy/Immunotherapy
Biology therapy is also called immunotherapy. It is done by assisting the patient’s own immune system to fight the tumor.
Blocks
Blocks are 5 to 8 cm thick blocks made of low melting point alloys that are cast with special technical equipment according to the shape of the irradiation field designed by the physician, in order to follow the shape of the tumor as closely as possible and to protect the surrounding normal tissues to the maximum.
Boost irradiation
After a certain base dose (usually 50~55Gy) has been irradiated to kill the tumor cells that are not visible to the naked eye in the normal tissues surrounding the tumor, the radiation therapist will reduce the irradiation area and further increase the irradiation dose to the tumor areas that are visible to the naked eye. The aim is to protect the surrounding normal tissues as much as possible while killing the maximum number of tumor cells.
Brachytherapy
Brachytherapy involves placing tiny radiation sources directly into or around the tumor tissue. Depending on the type of tumor, the tiny radiation source may remain in the body for a short period of time or permanently. In order to accurately place and secure the source in the treatment location, special catheters or instruments are often used to introduce the source.
There are two types of brachytherapy: intracavitary radiation therapy and intertissue radiation therapy. Intracavitary radiation therapy involves the placement of tiny radiation sources into the natural cavities of the body where the tumor is located, such as the cervix, vagina, and trachea. Interstitial radiation therapy involves placing a tiny radiation source directly into the tumor tissue being treated, such as the prostate and breast.
Placement of the source sometimes requires anesthesia and hospitalization for several hours to several days for observation.
Permanently implanted microscopic radiation sources have a very low energy level (but enough to kill surrounding tumor cells) and a short effective time, so patients can resume their daily activities soon after implantation. For short duration brachytherapy, the source will remain in the treatment location for several hours to several days, when the patient is asked to stay in a separate room, this is to avoid excessive activity causing the source to shift, resulting in inaccurate irradiation, and because the intensity and duration of effectiveness of this type of tiny radiation source is relatively long, in case it is dislodged and lost in the public environment, it will cause a serious radioactive environmental contamination accident, damaging to normal people and the environment. Damage to the normal population and the environment.
At present, the more commonly used is the high dose rate after-loading treatment machine, which applies the high intensity microscopic radiation source, through the pre-placed catheter, by computer remote control, the radiation source will be delivered to the designed treatment location, and stay for a pre-calculated time to treat the tumor. The treatment time of this device usually takes only 10 to 20 minutes.
The vast majority of patients experience only mild discomfort during treatment, partly due to the catheter or device that holds the radiation source, but these conditions usually adapt and disappear quickly.
Depending on the radiation source used, some patients must avoid children and pregnant women during and for a period of time after treatment, as children and pregnant women have fetuses that are more sensitive to radiation and are susceptible to radiation damage.
Chemotherapy
A method of treating tumors by using anti-cancer drugs, such as oral, intramuscular and intravenous injections.
Clinical trials
The process of testing a new drug or method of treating a tumor on a patient or healthy person.
CT or CAT scan
It is the application of X-ray imaging principles and computer-aided technology to produce an accurate structural picture of a cross-section of the human body. Both the Chinese and English full names are too long, so the clinical abbreviation is abbreviated to CT in English.
Three-dimensional conformal radiation therapy (3D-CRT)
The shape of tumor is irregular, and the shape and size of tumor are different when viewed from different angles. Three-dimensional conformal radiotherapy is the application of special computer software and imaging technologies such as CT, MR and PET-CT to create three-dimensional images of the tumor and surrounding normal tissues and organs, clearly displaying their location, shape, size and position in relation to each other. In this way, the doctor can design an irradiation field that is precisely the same shape and size as the tumor at any angle and position, so as to accurately irradiate the tumor while protecting the normal tissues and organs.
External irradiation (EBRT)
External irradiation means that the radiation source is located outside the body, at a certain distance from the body, and the radiation is directed to the tumor site through the body surface to kill the tumor cells, but at the same time, normal tissues are inevitably irradiated along the path of the radiation incidence. In order to minimize the reaction of normal tissues, conventional external irradiation is performed once a day for five days from Monday to Friday, with Saturday and Sunday off, for a total treatment period of 3 to 8 weeks. This achieves the goal of killing the tumor while protecting the normal tissues.
The most common device currently used for external irradiation is the linear gas pedal, which produces high-energy X-rays and electrons for tumor treatment. Radiation therapy professionals (including radiation therapists, technologists, and physicists) apply a variety of specialized techniques to accurately irradiate the tumor site to kill tumor cells while reducing damage to normal tissue.
Gorey (Gy/Gray)
This is the unit of dose for radiation therapy and is used to indicate how much radiation a patient has received.
Hormone therapy (Hormone therapy)
The body’s natural hormones such as estrogen and androgen can promote the growth of certain tumors under certain circumstances. Treatments that reduce the level or effect of hormones through surgery, radiation therapy or drugs are called hormone therapy or endocrine therapy.
Hyperfractionated radiation therapy (HFRT)
This is an improved form of radiation therapy compared to the conventional radiation therapy of 1.8~2.0Gy/time, 1 time/day, 5 days/week, where the dose is reduced to 1.0~1.2Gy per time, 2 times per day, and the interval between the two times is 6 hours or more.
Hypofractionated radiation therapy (HFRT)
Hypofractionated radiation therapy is the opposite of conventional radiation therapy in that a higher dose is administered each time and the total number of radiation treatments is reduced accordingly.
Immobilization dervice
This includes a variety of postural fixation frames for different parts, vacuum postural fixation bags, thermoplastic meshes, etc. The purpose is to help patients keep their bodies stable during radiotherapy and avoid inaccurate irradiation due to body movement.
Image Guided Radiation Therapy (IGRT)
The location of the tumor can move during treatment due to different levels of organ filling (such as the stomach or bladder) or due to respiratory movements. In order to irradiate the tumor more accurately, professional designers install CT, ultrasound imaging equipment or X-ray examination equipment into the radiation treatment room. After the patient is fully fixed in the treatment position, the above-mentioned imaging equipment is applied to obtain the real-time position of the patient’s tumor before or during the start of treatment, and then compared with the imaging data at the time of the patient’s positioning to derive whether the tumor has shifted, and once If the tumor is found to be shifted, adjustments can be made immediately so that the irradiation field is accurately re-irradiated on the tumor, thus achieving real-time image monitoring and guiding the precise execution of the irradiation field.
Intensity Modulated Radiation Therapy (IMRT)
Intensity-modulated radiation therapy is a special form of three-dimensional conformal radiation therapy that allows the irradiation field to more precisely conform to the shape of the tumor. It is based on the principle of splitting each large field into many smaller subfields, each of which can be adjusted in intensity to achieve a more precise irradiation of the tumor while better protecting normal tissue. In most cases, it is possible to increase the dose of tumor irradiation, which further increases the possibility of tumor cure.
Linear accelerator (linac)
It is a treatment device specially designed for external irradiation, which can produce photon rays (X-rays) and electron rays (β-rays) for the treatment of tumors.
Magnetic resonance imaging (MR or MRI)
Magnetic resonance imaging (MRI) is a technique that uses the different responses of different tissues in the human body to a magnetic field, combined with computer technology to process the signals generated by the responses of different tissues in the human body to the magnetic field, to create a fine image of the human body structure at the examination site.
Multileaf collimator (MLC)
It is a special device installed on the gas pedal to form an irradiation field corresponding to the shape of the tumor, thus achieving conformal irradiation.
Palliative care (Palliation)
In some cases, surgery, radiation therapy or chemotherapy is used only to reduce the patient’s pain and improve the patient’s quality of life, not to cure the tumor, and the treatment in such cases is called palliative care.
PET
PET is positron emission tomography in Chinese. It is a very small dose of radioactive tracer that is attached to glucose and injected into the body. Using this property, the scan detects the glucose utilization in different areas, and an image can be derived that shows those areas that have the metabolic characteristics of a tumor, that is, the presence of a tumor.
Proton and neutron RT (proton and neutron RT)
Both proton and neutron radiotherapy are a form of external radiation. They are characterized by their ability to irradiate and kill tumor cells more precisely or effectively. However, because the equipment used to generate the proton and neutron RT is extremely expensive and technically demanding, only a few centers in a few countries around the world currently have such equipment.
Radiation resistant (Radioresistant)
is a technical term used to describe types of tumors that are insensitive to radiation and are highly resistant to it, and conventional radiation therapy cannot kill such tumor cells.
Radioprotector
A class of drugs used to protect normal tissues at the site of irradiation.
Radiosensitizer (Radiosensitizer)
A drug used to increase the sensitivity of tumor tissue to radiation.
Stereotactic Radiation Therapy (SRS/SBRT)
Stereotactic radiation therapy is a special form of external radiation. By fixing the patient in an accurate position, the tumor location and shape are precisely determined, and a focused beam of radiation is applied, ultra-precise radiation therapy is administered to the tumor. This technique allows the radiotherapist to administer a high dose of radiation therapy to the tumor in a short period of time, usually within 1-5 days, whereas conventional radiation therapy usually takes several weeks.
There are two forms of stereotactic radiation therapy, one is called stereotactic radiosurgery SRS, which involves a radiation oncologist working with a neurosurgeon to develop precise radiation therapy for brain and spinal cord disease. Another type of radiation therapy is called stereotactic body radiation therapy (SBRT), which refers to precise stereotactic radiation therapy to parts of the body other than the brain and spinal cord.
The advantage of stereotactic body radiation therapy is that it can irradiate tumors with high dose precision in a short period of time, which also minimizes the damage to the surrounding normal tissues. The disadvantage is that it can only be used for small tumors that can be well visualized on CT or MR.
Stereotactic radiation therapy techniques are often used in clinical applications under their brand names including Axesse, Cyberknife (Cyberknife, Radio Knife), Gamma Knife (Gamma Knife), Novalis, Primatom, Synergy, X-Knife (X-Knife), Tomo Therapy, or Trilogy, etc. . These are actually the brand names of different manufacturers of stereotactic radiotherapy equipment.