Types of Equipment
In order to ensure precise delivery of your treatment, a series of medical equipment and computer systems are used in radiation therapy.
During your treatment, you may hear some of the following names and abbreviations:
An aperture is a device that helps shape the radiation beam in proton therapy. Each individual’s tumor will be unique and will require a specific aperture to spare healthy tissue from being irradiated. Most apertures today in proton therapy are made of brass. A patient may have one to three apertures per treatment field.
In proton therapy, the beamline is a metal tube that the particles travel through from the cyclotron to the snout. Magnets are placed along the beamline to focus and steer the particles to assure the beam is accurately delivered to the patient.
A compensator is similar to a MLC in the fact that it adjusts the intensity of the beam to deliver the planned dose to the treatment volume and to limit does to the surrounding critical structures. This technique is not often used in conventional radiation therapy but is utilized often in proton therapy. These devices can be made out of brass for conventional radiation therapy and acrylic or wax for proton therapy.
A cyclotron is used to accelerate particles for the treatment of tumors with proton therapy. Cyclotrons can have different ranges of energies most commonly from 70 MeV – 230 MeV. The energy corresponds with the depth the particles will travel in the body.
An Electronic Medical Record is your virtual medical chart. An EMR has many advantages from digitally recording complex treatments, checking drug interactions, and keeping the medical staff informed about your care. One specific type of EMR is an OIS (Oncology Information System). An OIS is a powerful information and image management system designed to support the clinical needs of oncology patients and their clinicians.
A High Dose Rate Afterloader is a machine that is used for a specific type of brachytherapy treatments. It aids in the precise location of brachytherapy sources and reduces radiation exposure to staff. It mechanically delivers a radiation source through a catheter to the area to be treated. The source remains there for a predetermined period of time to deliver a treatment and is then retracted.
Image Guided Radiation Therapy is the process of using different imaging methods to ensure the patient/tumor proper position with precision accuracy. IGRT allows for better positioning because it is based on internal anatomy or fiducials instead of external skin marks. When utilizing IGRT a small treatment volume can be created which reduces dose to healthy tissue. There are different forms of IGRT you may learn about: Conebeam CT (CBCT), orthogonal x-ray, and ultrasound.
LINear ACcelerator is a term most often used in the photon treatment realm. The LINAC is part of the treatment machine that accelerates photons or electrons intended to treat the tumor. The term also is a generic term for the treatment machine. Varian, Elekta, Tomotherapy, and Cyberknife all use some form of a LINAC and are often categorized as such.
A multi-leaf collimator (MLC) consists of 80 to 160 moveable “leaves” that serve two purposes. The first is to form the shape of the radiation beam to coincide with treatment plan to irradiate the tumor. In conventional radiation therapy this can be accomplished with custom blocks made out of metal alloy if an MLC is unavailable. The second is to modulate or adjust the intensity of the beam to deliver the planned dose to the treatment volume and to limit dose to surrounding critical structures adjacent to or in the treatment field.
A snout is a device on a proton therapy treatment machine that aids setting the field size. In addition, the snout serves as the device that holds apertures and compensators in place during treatment.
Thermo Luminescent Dosimeter works by converting radiation into visible light. TLDs are a form of in-vivo dose measurements. In-vivo dose measurements have many applications; one is to confirm a patient dose exposure. Another type of in-vivo dosimeters are diodes.
Treatment Planning System
The treatment planning system is utilized by a physician and oncology team to develop a treatment plan. This process can take several days depending on the complexity of the case. During the planning process, a highly advanced computer and software program is used to virtually plan out your treatment. Ultimately, an optimized plan will be made to spare the healthy tissue as much as possible while treating the tumor and limiting does to surrounding healthy tissues. Each person is unique so each plan is based on the individual’s anatomy and tumor.