Outline of treatment
A linear accelerator (LINAC) delivers high-energy radiation to lesions in order to shrink or destroy tumors. Radiation damages genes (DNA) in tumor cells, leading to their destruction.. This feature can be used to treat tumors and alleviate symptoms due to tumor enlargement, such as pain. Normal cells are also damaged by radiation, but have a higher capacity to repair themselves than tumor cells. Therefore, radiation is delivered daily at a low dose that destroys tumor cells while damaging normal cells as little as possible.
Diseases treated with LINAC
- Malignant thyroid lymphoma
- Thyroid cancer
- Bone metastases of thyroid cancer
- Thyroid-associated ophthalmopathy (benign disease)
Steps of treatment
- (1) Pretreatment examination
- A mask is designed to keep the patient in position for the procedure and CT scan is performed to determine the treatment area and radiation dose.
- (2) Dummy test
- A test is performed using a measuring device to confirm that the intended radiation dose is emitted as planned. A doctor and a radiologic technician perform this test before treatment begins.
- (3) The first day of treatment
- To confirm the area of treatment, the positioning mask is attached to the patient and a CT scan is performed. This process takes approximately 30 minutes and confirms that the positioning is accurate. Marks are then placed on the mask to be used as reference points in subsequent sessions. Treatment then begins. Radiation is delivered for a few minutes. After treatment, medical examination is performed.
- (4) From day two until the end of treatment
- Patients stay in the treatment room approximately 10 minutes for each session. In the treatment of thyroid cancer or bone metastases from thyroid cancer, confirmation of positioning is performed using a CT scan once a week as it was in the first session.
For treating other diseases, positioning is performed as necessary before treatment begins.
A medical examination is performed after every treatment.
- (5) Duration of treatment and effects
- For thyroid-associated ophthalmopathy, a standard course of therapy is 10 sessions over a period of two weeks. For other diseases, the duration of treatment varies depending on the specific area and radiation dose required. Therapeutic effects may appear after a few months or even one year.
In this type of therapy, adverse reactions often occur in the area of radiation exposure. For example, treatment of the head causes hair loss and nausea, while treatment of the neck causes sore throat and impaired saliva secretion. The skin in the treatment area may turn red. Although there are individual differences in these adverse reactions, they tend to occur after the 10th treatment session and persist for a few weeks after the completion of treatment before gradually resolving. Therefore, regular medical examinations are needed after completion of treatment to manage adverse reactions in their early stages.
Introduction of a new device
We replaced our hospital’s LINAC device in 2015. The largest difference between the new and old devices is that new LINAC uses a multileaf collimator with a leaf width of 5 mm. This means that the new device is much more precise and it is possible to deliver radiation exclusively to the tumors. In addition, radiation can be emitted from various angles. This works to disperse the load on normal tissues, and thereby further reduces damage to them. A reduction in the area of high radiation exposure can be expected to minimize skin redness and hair loss. In the same fashion, avoiding irradiation of the salivary glands is expected to lessen harmful effects on saliva production. In addition, the new LINAC has remarkably improved accuracy of positioning. It allows performance of image-guided radiotherapy (IGRT), and we provide treatment in which the error in the area of radiation exposure is minimized.
Additional information regarding treatment
- ・Outpatient treatment is available.
- ・Hospital visits for treatment, including a medical examination, last for about 1-1.5 hours.
- ・For the treatment of the head or neck, a positioning net is used. For the treatment of other areas, the skin may be marked with a special felt marker.
- ・Patients stay in the treatment room alone during radiation treatment while a staff members overseeing the treatment watches on a monitor. Patients can speak with the overseeing staff member through a microphone. Also, patients are provided with a buzzer to sound in the case of an emergency. If the patient has any concerns or worries, they can speak directly to the staff member overseeing the treatment.
The skin area to be irradiated must be exposed during treatment, but patients do not have to change clothes.
Precautions during treatment
- ・Skin in the treatment area tends to be affected by radiation. During the period of treatment, irritation of the skin should be avoided. In order to lessen the risk of skin reactions, cosmetics and sunscreens should not be applied to the treatment area. Also, skin irritation needs to be avoided for approximately one month after completion of treatment. However, during this period following treatment the skin should be protected from ultraviolet light by using sunscreens or other means.
- ・Patients can live a normal life without restrictions during treatment, although some may feel fatigue or sluggishness. Patients should try to continue the routines of daily life.
- ・Smoking during the period of radiotherapy may interfere with treatment. We strongly recommend that patients abstain from smoking during treatment and after its conclusion.