Introduction:
Radiation therapy treats gynecological cancers with chemotherapy, surgical recession, immunotherapy, etc. Two methods can do radiation therapy the external beam of radiation, which uses an external machine that delivers the radiation to the body, and using internal radiation or brachytherapy, which uses internal radiation seeds which provide radiation to the targeted site. In an external beam of radiation therapy, different intensities of radiation can be used to treat cancer depending upon the severity and spread of cancer, and they are called intensity-modulated radiation therapy (IMRT).
What Is Intensity-Modulated Radiation Therapy?
Intensity-modulated radiation therapy is a type of treatment that is used to do to cure cancer. It is an advanced type of radiation therapy that uses small photon beams to deliver radiation in the shape of a tumor. The intensity of radiation from this therapy is controlled, and it avoids radiation exposure to healthy tissue, limiting the damage to healthy normal tissues surrounding the tumor. Intensity-modulated radiation therapy can be used to treat prostate cancer, lung cancer, brain cancer, breast cancer, and most head and neck cancers. It can be used to cure lymphomas, sarcomas, and gynecological carcinoma.
What Is Pelvic Intensity Modulated Radiation Therapy?
Pelvic intensity-modulated radiation therapy is used as a neoadjuvant therapy before the surgical removal of cancer for shrinking the tumor for easy tumor removal and as adjuvant therapy after the surgical resection of the gynecological malignancies. Intensity-modulated radiation therapy kills cancer cells, prevents cancer recurrence, and prevents lymph nodal metastasis. Intensity-modulated radiation therapy can use various radiation intensities to treat cancers and does not disturb the adjacent normal tissues from radiation. There is an advanced technology to direct the radiation beams to the tumor's shape. It uses multiple small photon beams to kill the tumor.
What Are the Techniques That Are Used for Delivering Pelvic Intensity-Modulated Radiation Therapy?
Intensity-modulated radiation therapy can be used to treat gynecological cancer, including cervical cancer, with the combination of chemotherapy and has a higher success rate than normal conventional radiation therapy. Intensity-modulated radiation therapy uses a non-uniform intensity pattern subdivided into various beamlets that can be focused directly on the tumor. Intensity-modulated radiation therapy uses a multi-leaf collimator (MLC). A multi-leaf collimator is a beam-limiting device made up of tungsten that can be moved within the path of the radiation beam to shape the beam and change the intensity. The common techniques for delivering intensity-modulated radiation therapy are -
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Segmental Intensity Modulated Radiation Therapy - For each beam, multi-leaf-shaped collimators are used. The radiation intensity is achieved by adding all the segments created by the multi-leaf-shaped collimators. After keeping the multi-leaf-shaped collimators in position, the radiation is turned on, and this process is called the step-and-shoot method. This is the most commonly used method in delivering intensity-modulated radiation therapy.
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Dynamic Intensity-Modulated Radiation Therapy - In intensity-modulated radiation therapy, the multi-leaf collimator moves continuously during the radiation therapy. The variation of the speed of the collimator and the distance between the multi-leaf collimator leaves at the specific point produces a different radiation intensity. Suppose the multi-leaf collimator is in line with the radiation beam. In that case, it will deliver intensified radiation to the tumor site, continuously increasing the total body radiation dose.
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Tomotherapy - In tomotherapy, radiation is directed to the tumor from different directions, like a fan beam. They are also called helical tomotherapy.
Why Is Pelvic Intensity-Modulated Radiation Therapy Preferred in Treating Gynecological Cancers?
Pelvic intensity-modulated radiation therapy is preferred in treating gynecological cancer over conventional radiation because it can cause minimal damage to the surrounding organs and tissues and decrease the radiation-related toxicity in other organs. Conventional radiation therapy for gynecological cancer can cause gastrointestinal toxicity and hematology toxicity. But when pelvic intensity-modulated radiation therapy is used for treating gynecological cancer, the gastrointestinal and hematological toxicity is seen to be reduced.
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The gastrointestinal toxicity seen in normal pelvic radiation therapy includes diarrhea, abdominal pain, abdominal discomfort, involuntary bowel and bladder movements, intolerance to certain food items, malabsorption, etc. In people with gynecological cancer who undergo pelvic intensity-modulated radiation therapy, there will be a decrease in the rates of acute or chronic gastrointestinal toxicity. Thus the use of antidiarrheal medications can be avoided compared with conventional pelvic radiation therapy.
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Hematological toxicity like decreased white blood cell count or myelosuppression (bone marrow suppression) is seen in conventional radiation therapy of the pelvic region in gynecological cancer. In pelvic intensity-modulated radiation therapy, hematological toxicity is reduced. Thus the use of chemotherapeutic drugs for hematological problems can be avoided in intensity-modulated radiation therapy cases.
What Are the Advantages of Pelvic Intensity-Modulated Radiation Therapy Over Conventional Radiation Therapy?
In normal radiation therapy, there are different configurations of wedges and beams used to get a desirable treatment plan to cure cancer, but intensity-modulated radiation therapy uses radiation doses depending upon the volume of cancer. The radiation will be directed to a target site depending on tumor size and volume. It decreases the exposure to normal tissues surrounding the tumor, like the small intestine, urinary bladder, large intestine, etc. The main advantage of pelvic intensity-modulated radiation therapy in gynecological cancer is that it can reduce the radiation dose to intraperitoneal pelvic contents like the stomach, spleen, liver, and small intestine than the surrounding pelvic lymph nodes reducing the side effects of the radiation to adjacent tissues and organs.
What Are the Disadvantages of Intensity-Modulated Radiation Therapy?
Pelvic intensity-modulated radiation therapy is used in treating gynecological cancer because it has many advantages, including decreased toxicity to surrounding organs and tissue, but it has some disadvantages. The disadvantages of intensity-modulated radiation therapy include the following -
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Increased time for targeting the tumor and organs.
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Increased planning time initially for the intensity and radiation.
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Increased treatment and appointment time.
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Increase in the total body radiation dose.
Conclusion:
Pelvic intensity-modulated radiation therapy can use different radiation intensities to treat gynecological cancer depending on the cancer volume and site of occurrence. It can deliver increased radiation intensity in areas prone to recurrence to prevent the development of cancer cells. Intensity-modulated radiation therapy is preferred over conventional radiation therapy because it has fewer side effects on normal health issues and prevents other toxicity from conventional radiation therapy.
