Modern radiotherapy and treatment of cancer

In 2020, there were about 200,000 new cancer cases in Thailand. Recent advances in the fields of surgical oncology, medical oncology and radiation oncology have immensely improved cancer treatment outcomes. Even with the best multidisciplinary treatment, the cancer recurs in more than half of patients and requires further treatment for relief in order to improve quality of life and hopefully prolong life. Radiation therapy is an important modality of cancer treatment with curative intent or palliative goals. Modern advanced radiotherapy techniques make it possible to deliver high doses of radiation to the tumor while minimizing radiation doses to the surrounding normal tissues. As a result, tumor control in the curative and palliative setting is far superior to the past.

Modern radiation therapy uses a high-energy beam to kill cancer cells, while diagnostic radiology uses low-energy, low-dose X-rays. Radiation therapy can treat all types and stages of cancer, alone or in combination with surgery and chemotherapy, depending on the type and stage of the cancer. The combinations can be given simultaneously or in sequences. There are two main types of radiation therapy: external beam radiation and brachytherapy.

The linear accelerator or LINAC is the most advanced external radiation therapy device used to treat cancer. It can deliver photons or high-energy X-rays and electron beams with high precision. This advanced, high-precision radiation therapy uses computers to control x-ray accelerators and deliver precise doses of radiation to a tumor.

With the invention of the computer-controlled multi-leaf collimator integrated into the modern LINAC system, modern radiation technology can treat tumors as small as 5 mm. up to a size of 40 cm. with high precision. The right amount of radiation is directed at the tumors while minimally irradiating the surrounding normal tissue. Advanced external beam radiation treatment techniques that are commonly used are: Intensity Modulated Radiation Therapy (IMRT), Volumetric Modulated Arc Therapy (VMAT), Image Guided Radiation Therapy (IGRT), Stereotactic Radiosurgery (SRS), and Stereotactic Body Radiation Therapy (SBRT).

The application of each technique depends on the location, size and type of tumor to be treated, which is carefully selected by the radiation oncologist to achieve the best possible treatment outcome. For example, image-guided radiation therapy (IGRT) is often chosen to treat tumors that tend to move, such as: B. a lung cancer nodule moving with respiration using the 4D gating technique which synchronizes the beam to the same phase as respiration cycles.

The LINAC system uses imaging technology to scan the tumor before or during treatment, and by comparing these scans to the simulated reference images, the radiation oncology team can make fine adjustments to your position and the beams to precisely target the tumor and at the same time avoid healthy tissue. The LINAC system scans the tumor before or during treatment, and by comparing these scans to the simulated reference images, the radiation oncology team can make subtle adjustments to your position and the radiation beams to accurately target the tumor while avoiding healthy tissue.

External radiation treatment is typically performed 5 days per week with 2 rest days in a row. Sometimes it can be 3 times a week. The course of irradiation usually lasts 4-7 weeks. Elekta’s Versa HD™ paired with the high-precision Catalyst+ HD patient positioning system enables precise radiation treatment in the same position from session to session throughout the course of radiation therapy. Radiation therapy for palliative purposes is given over a shorter period of one to two weeks. However, with stereotactic radiosurgery, the radiation is delivered in a single session.

Procedural Suite with Flexitron Brachytherapy Afterloader by Elekta

Brachytherapy is a type of internal radiation therapy in which seeds, tapes, or capsules containing short-range radioactive sources are placed in or near the tumor during the treatment session and removed from the body after treatment. Therefore, no radioactive source remains in the patient. Normal tissues in the beam path are not necessarily irradiated, as with external radiation therapy.

Brachytherapy is one of the most precise forms of radiation therapy, capable of delivering a very high dose of radiation to the tumor with much less radiation to the normal surrounding tissue, resulting in better tumor control with fewer complications. It is given in multiple sessions spaced a few days or weeks apart. For a patient with prostate cancer, brachytherapy is an appropriate treatment. It is convenient and safe and does not require hospital admission.

Unlike prostate surgery treatments, the patient does not have to stay in the hospital for a week or more with an indwelling catheter and can resume normal routine activities and even have sex the day after the procedure. The complications of brachytherapy are minor and in most cases non-existent. Elekta’s Flexitron™ brachytherapy afterloader unit ensures the most sophisticated and safest brachytherapy procedure possible, with a streamlined process and greater efficiency.

Modern radiation therapy treatment is a complex process involving planning and delivery, made possible by advanced digital imaging and sophisticated computer technology, with each step of radiation therapy controlled by a high-energy linear accelerator source. Coupled with the input and expertise of the Radiation Oncology team, patients receive faster, more streamlined, safer, and more precise treatments with an improved quality of life.

Author: Dr. Yongyut Kongthanarat, radiation oncologist, MedPark Hospital

Series Editor: Katalya Bruton ([email protected]), Health Content Editor and Director, Dataconsult Ltd. Dataconsult’s Thailand Regional Forum in Sasin offers seminars and extensive documentation to keep companies up to date on future trends in Thailand and the Mekong region.