Radiation therapy is transmitted in the form of light waves or high-speed particles. The use of high-energy radiation to treat tumors or certain diseases is called "radiotherapy," known as "electrotherapy." High-energy radiation that treats tumors can kill cells in the body and prevent the cells from growing and dividing. The amount of growth and division of tumor cells is more vigorous than that of normal ones. By using such properties, radiation therapy is able to destroy the tumor cells that are rapidly growing and dividing, while the normal tissue has the better ability to repair itself and thus there is less damage to surrounding normal tissues.  

 

The radiation therapy services we offer   keep up with the world's advanced medical centers, including general 2D radiotherapy, three dimensional conformal radiotherapy (3D-CRT),   intensity-modulated radiation therapy (IMRT), electron radiation therapy, brachytherapy, as well as image-guided radiation therapy (IGRT), helical tomotherapy, stereotactic radiosurgery (SRS), stereotactic body radiation therapy (SBRT), total body irradiation (TBI), respiratory gating radiotherapy (RGRT) and volumetric modulated arc therapy (VMAT)-RapidArc technique.  

 

Brachytherapy is a radiotherapy that directly puts a radioactive source in tumor tissue or near a dangerous area. It has been used for more than 80 years in the treatment of cancer. Brachytherapy is often applied to cervical cancer, endometrial cancer, and prostate cancer, and can also be used in other tumors where the catheter can be inserted.

 

Brachytherapy has many advantages over external beam radiotherapy because of its unique physical properties. For example, the radiation dose accepted by normal tissues near the tumor is significantly reduced, and the radioactive source and the scope of treatment will not be altered by the patient or tumor movement. Therefore, the tumor itself can be given fairly high-dose therapy, while the chance for normal tissue to be harmed greatly decreases.

 

The division has a complete set of brachytherapy systems and clinical experience for over 20 years. Brachytherapy is commonly applied to cervical cancer and endometrial cancer in the hospital, especially in the treatment of advanced cervical cancer, which is superior to those of many advanced countries. In addition, brachytherapy is used in patients with esophagus cancer, bile duct cancer, and locally recurrent nasopharyngeal carcinoma.

IMRT stands for Intensity-Modulated Radiation Therapy. The purpose of the design is to adjust the radiation dose distribution according to the shape of the tumor itself and the location of surrounding tissue, with the goal of concentrating the high dose area at the tumor and reducing normal tissue injury.  

 

In the history of the development of radiation therapy, it began with 2D plane design: the irradiated part was only able to move along the X-axis and Y-axis. Due to the progress of computer hardware and software, conformal radiotherapy (CRT) appeared, whereby the information obtained by computed tomography (CT) can recombine the shape of the tumor and design a dose distribution that corresponds to its external pattern, and multiple irradiation is carried out at different incident angles and each field dose is distributed evenly. IMRT can be viewed as an enhanced version of CRT in some way, making the most appropriate distribution of beam intensity. At present, it is theoretically applicable to tumors in all parts, especially to prostate cancer, head and neck tumor, breast cancer, lung cancer, and cervical cancer.     

Image-Guided Radiotherapy (IGRT) can actually monitor tumor changes.

 

Although radiotherapy has been based on 3D technology, the human body is a dynamic environment and the tumor in the body cavity cannot avoid the influence of normal respiratory movement and gastrointestinal motility. Moreover, in the radiation biology, most tumors are still irradiated for multiple days. After one or two months of treatment, with tumor reduction and weight changes, plus daily set-up errors and other factors, there will be more or less influence on the distribution changes of radiotherapy doses and treatment results. IGRT allows us to quickly and accurately make adjustments according to the position of the internal organs of the patient at any time, rather than relying only on the external mark of the body.

 

In addition, the division has a complete set of radiosurgery systems with strict treatment accuracy. It can carry out image-guided radiosurgery (IGRS) on the body cavity and within the cranium. It provides another way of treatment for patients who are unfit for an operation due to their illness or physical condition.

Traditional radiotherapy is performed after the mark on the patient's skin is matched. However, the daily position of a tumor or organ may be displaced by many factors, resulting in errors. More normal tissues will be affected if the scope of treatment is increased to avoid omission of radiation. But now, tomotherapy uses a CT scan for image guidance, so that the medical team can adjust the positioning according to the latest location in order for radioactive rays to reach the target position accurately.

 

Helical tomotherapy can move the beam forward with a 360-degree spiral for radiation therapy and thus can achieve better therapeutic effects and protect normal organs. Even if there are multiple tumor locations, they can be dealt with simultaneously. It differs from the conventional linear accelerator that requires segmented irradiation and thus can shorten treatment time. Metastatic tumors can also be eliminated one by one   and treatment can be tailored to the needs of each patient, with the aim of increasing the chance of survival.

 

Tomotherapy is applied to tumors in all parts of the body such as brain tumor, head and neck nasopharyngeal carcinoma, oral cancer,  laryngeal cancer, esophagus cancer, lung cancer, liver cancer, gynecologic cancer, and prostate cancer.

RapidArc is a single / multi-ring volumetric modulated arc therapy (VMAT) technique. Compared with conventional IMRT, RapidArc can finish the radiation in a shorter time, and exclude the radiation injury caused by the patient's involuntary movement, in an attempt to improve accuracy and reduce side effects. The RapidArc technique, along with VMAT, is mainly applied in the IGRT and IMRT stereotactic radiotherapy. 

 

The difference from general helical tomotherapy equipment is that its maximum beam angles can effectively lessen normal tissue doses. Moreover, as general helical tomotherapy adopts multiple irradiation with segmented slice-by-slice propelling and RapidArc adopts full-volume single irradiation, a tenth of the radiation output of tomotherapy can reach the therapeutic dose and reduce the patient’s systemic scattered dose.

Both stereotactic radiosurgery (SRS) and   stereotactic radiotherapy (SRT) employ stereotaxic techniques for lesion localization and irradiating the target area. SRS gives a single, high dose of radiation, while SRT gives multiple fractionated irradiation.

 

SRS is applicable to tumors with small lesions, which can be destroyed with a single, high dose of radiation, while SRT is suitable for tumors with slightly larger lesions, and has the advantage of increasing the sensitivity of tumor cells to the radiation and the opportunity to repair the normal tissue.

 

SRS gamma knife indications include: benign intracranial tumor, malignant metastatic brain tumors, and arteriovenous malformation.

Stereotactic body radiation therapy (SBRT) is a precision technology by which accurate doses for radiation therapy are given in a very conformal way in several times. In addition to precise alignment, SBRT also needs to factor in the movement of the target volume of radiotherapy in the body. SBRT usually uses multiple beams to treat the lung’s peripheral tumors. After SBRT therapy, the local control rate of the tumor is usually up to 80 percent or more, and the incidence of severe (level 3 or above) side effects is usually less than 10 percent. Currently,  SBRT has been considered as one of the rational treatments for lung and other body tumors. It is most frequently applied to early lung cancer or oligometastatic lung cancer unfit for surgery. The hospital has also begun to implement SBRT as of 2011.

With the advancements in science and technology, the technology of radiation therapy has also entered an age of "four-dimensional radiation therapy." The so-called four dimensions refer to time as another dimension, along with length (x), width (y), and depth (z). Such a technique is particularly helpful to the change of the position (e.g. respiratory movement) during radiotherapy. Chest radiotherapy for lung cancer for example, planed and implemented with a four-dimensional approach has become a growing trend.  

 

Since the spring of 2009, China Medical University Hospital’s (CMUH) Radiation Oncology Division has applied four-dimensional radiotherapy (4DRT) to chest radiotherapy.