Radiation Therapy Terms
What is a Pendant?
Is located on the foot of our Varian TrueBeam machines (2 of them) and is a hand held device that allows you to move multiple things on the treatment machine. Examples: allows you to move the treatment couch, move imagers, move the gantry, move the collimator, move jaws, open MLCs, turn on treatment lights, ODI, turn on the lasers, etc.
What is a Vac-Lock?
A type of immobilization device used by some patients for treatment. They can be utilized for the upper and lower portions of the body. Vac-locks are similar to a beanbag's material and are used to mold to the patient's body. A vacuum is used in the simulation to suck out the air of the vac-lock to tightly mold the patient's body. The purpose of using these are to make sure the patient is in the exact same position for treatment as they were in for their simulation
What is "Sticking with Lats?"
What is a Bolus?
A material used that substitutes as "skin tissue" and causes the radiation dose to treat more superficially. Examples of bolus at our site include: FlexiBol, wet towels, and SuperFlab
What is a CT simulator?
Is a type of 3D planning system where images are acquired from a CT simulator machine. Patients will be placed on the CT table during their simulation and will go through a "tube" where multiple images will be acquired. The images taken are then sent to dosimetrists and doctors for treatment planning purposes for the cancer.
What is a PTV?
Stands for Planning Target Volume. Is a volume created by physicians for treatment planning. The PTV encompasses the GTV and then allows a margin for any patient movement or positioning variabilities.
What is a "Couch Kick?"
This is where the treatment couch will "kick" itself and move to a position that is not set at a 0 degree rotation. Many times, patients can have couch kicks planned as part of their treatment and used as one of their treatment fields.
Stands for "source to skin distance" and represents a numerical measurement from the source of radiation to the skin of the patient. The standard SSD is 100cm but if the treatment has an extended SSD, this means that the SSD measures greater than 100cm. At our site and many other sites, SSD measurements are taken weekly and are done so to ensure that there are no major changes in the numbers.
What is an IMRT?
Stands for Intensity Modulated Radiation Therapy. It is where high energies of radiation are used to treat the cancer. It is a technique that creates more preciseness and accuracy when delivering radiation. Surrounding organs are spared to the best of their ability with this technique.
What is a Boost?
What is a Fraction of Treatment?
Represents small doses a patient will receive. A patient's treatment schedule is often split into "fractions." These fractions of treatment accumulate overtime to reach the full desired radiation dosage.
Stands for Cone Beam Computed Tomography. It is a type of imaging where the gantry will rotate around the patient to capture a 3D image of the treatment area. Often at our site, we call this one "arc". Varying patient to patient for treatment, there will be different amounts of arcs used for radiation treatment.
What is a Surface Guided Radiation Therapy?
A commonly used system where multiple cameras are utilized in the treatment room to track the movement of the surface of the body. This is a way to ensure that the patient is correctly positioned for treatment. A computer located at in the treatment room and one at the console area can both show how well the cameras are picking up the patient's surface of their body. Different colors are indicated to show whether or not the positioning is within tolerance for accurate treatment. At our site, this system is often used for DIBH breast patients, some SBRT patients, and SRS patients.
A type of system that tracks the patient's tumor as they breathe. The system is beneficial for determining whether or not the patient's breathing will affect accurate targeting of the tumor. This system is also often an alternative that can be used for patients who are poor candidates for DIBH (deep inspiration breath-holds).
What is a Static Fields?