Many cancer patients receive radiation therapy, either alone or in combination with surgery or chemotherapy. Image-guided radiation therapy targets the DNA of cancer cells. Over time, this leads the cancerous cells to stop dividing or to die. Radiation therapy can be used before surgery to shrink a tumor, during surgery (a way to protect nearby healthy tissue), or after surgery to destroy any remaining cancer cells.
The radiation is delivered using a sophisticated machine called a linear accelerator (LINAC) which generates x-rays or electrons of a specific high energy, in the form of a beam that is then carefully shaped and aimed at target regions.
On-board imaging enables the treatment machine to acquire images of a treatment site in the body prior to and during radiation treatments to ensure the target and normal tissues are well positioned.
The LINAC can take x-ray images as well as low dose “cone beam” CT scans for 3-dimensional anatomy visualization, and those images are used to refine the daily alignment and ensure accuracy.
Radiation Oncologist Lindsay Jensen, MD
3D Conformal Radiation: Uses multiple fixed beams of constant shape to treat a region of the body while blocking out dose to surrounding tissues.
Intensity-Modulated Radiation Therapy (IMRT): Using sophisticated computer-controlled movements of the treatment machine, a radiation dose is “painted” on a target within the body while minimizing dose to adjacent tissues. Multiple fixed positions of the treatment machine are used, and treatment times vary.
Volumetric-Modulated Arc Therapy (VMAT/RapidArc): Similar in scope to IMRT treatments (see above) but the “painting” of the dose occurs as the machine is constantly rotating through one or more arcs around the body. This usually results in faster treatment times than a more traditional IMRT plan.
Stereotactic Body Radiation Therapy (SBRT) / Stereotactic Ablative Body Radiotherapy (SABR): Used to deliver high doses of radiation precisely to targets within the body, usually in three to five treatment sessions. Most often used for lung, spine, prostate, isolated liver and adrenal tumors.
Stereotactic Radiosurgery (SRS): Typically a single very high dose of precisely aimed radiation to targets within the brain.
Electron Therapy: Used to treat superficial locations (eg: skin cancers, some breast cancers) by utilizing some of the physical properties of these particles.
Unsealed Sources: Via Olympic Medical Center in Port Angeles, we also offer “unsealed source” therapy, such as Radium (aka “Xofigo”) for metastatic prostate cancer, and Samarium for bone pain relief from a wider range of metastatic tumors.
Deep-Inspiration Breath-Hold (DIBH) treatments are used to help limit, even further, small doses to the heart tissue for left-sided breast cancer treatments, or to patients with lymphomas occurring in the center of the chest.
Prone breast radiation treatments for breast cancer therapy allow the treated breast tissue to pull away, via gravity, from the chest and can reduce exposure to sensitive underlying tissues.
The advanced-imaging capability enables the treatment machine and treating staff to track implanted markers in real-time during each radiation treatment. This is most commonly utilized during prostate cancer and some lung cancer radiation treatments where there can be significant movement of the targets during treatment delivery. Other specialists (eg: urologists, pulmonologists, surgeons) typically implant those markers prior to radiation therapy.
A 6-degree-of-freedom “couch” allows both very fine-tuned rotational (pitch/roll/yaw) and translational (up-down/left-right/top-bottom) adjustments to be made on a daily basis before treatments to ensure precision alignment.
In addition, we consult and coordinate with other clinics that may provide other specialized procedures such as low dose rate (LDR) brachytherapy, high dose rate (HDR) therapy, and proton/particle therapy, if these are needed for comprehensive cancer care.
