If an oncologist wants to use radiation to treat a cancer patient, he or she will need to work with a dosimetrist. A dosimetrist is a medical professional who specializes in radiation dosage and how to deliver it to a patient in the most efficient way possible. He or she assesses the doctor’s radiation prescription and determines the best way to deliver it to the tumor while minimizing damage to the patient’s surrounding tissues and organs.
Brachytherapy and teletherapy are two techniques that a dosimetrist must be familiar with. Brachytherapy is a treatment method in which a source of radiation is applied very close to a tumor, sometimes even within the patient’s body. This practice helps to focus the application of radiation on the tumor, reducing the risk of damage to healthy tissues from irradiation. Teletherapy is the practice of using a beam from outside the body to target a tumor. Depending on which technique is more appropriate for the situation, both can be used.
When the dosimetrist receives the oncologist’s radiation prescription, he or she must assess the patient’s needs in order to design a treatment plan. To plan for the correct dosage, calculations must be performed manually or using a computer. Any healthy tissues or organs located near the treatment site must be given special consideration. Dosimetrists must be aware of dose-limiting structures and devise a plan that will effectively apply the radiation without harming them. 3-D images or scans, such as MRIs or PET scans, are frequently used to help define the tumor’s location and position relative to these structures.
Following the creation of a plan, the dosimetrist may conduct a treatment simulation to ensure that it will work as expected. During the test, he or she may determine whether parts of the patient’s body should be immobilized during treatment to protect healthy tissues and ensure that the radiation is applied correctly. In these cases, it may be necessary to create casts or molds.
Another area where a dosimetrist must have extensive training is in the use of radiation therapy equipment. He or she is in charge of calibrating and ensuring that the treatment machinery is up to par. The dosimetrist frequently collaborates with a medical physicist to carry out the treatment with the proper equipment, ensuring that it is carried out safely and correctly.