UNAIR NEWS – Nowadays, therapeutic methods with radiotherapy have been widely applied, including cancer therapy. In her research on “Cancer Therapy Through LINAC”, Dr. Suryani Dyah Astuti, M.Si., first explained that radiotherapy uses ionizing radiation such as X-rays, gamma radiation or high-energy electrons to kill as many cancer cells as possible and as little as possible has a negative effect on the surrounding healthy tissue.
Furthermore, Dr. Dyah also explained about radiotherapy that uses radiation from outside the patient’s body, the external radiation. External radiation can use a Linear Accelerator (LINAC) or Cobalt-60 which generally can emit photons or electrons with an energy of 6 MeV or 10 MeV.
Selanjutnya, Dr. Dyah menjelaskan bahwa prinsip kerja LINAC yaitu mempercepat elektron sehingga energi kinetiknya bertambah dari 4 MeV menjadi 25 MeV. Yang di dalamnya, elektron dipercepat mengikuti lintasan yang lurus pada struktur khusus yang dinamakan Accelerating waveguide. LINAC juga dilengkapi dengan beberapa pilihan berkas radiasi, yaitu berkas elektron dan foton.
“The control system for photons and electrons produced by Linac uses a control system with a computer, a body scanning system using an Electronic Portal Imaging Device (EPID), radiation dose control using a Multi-Leaf Collimator (MLC) and a full dose setting using intensity modulation. Treatment Planning System (TPS) Technology at LINAC uses 3D calculations with MLC system that can produce a precise form in the treatment of radiation volume target “, she explained.
In his research, Dr. Dyah also reviewed about LINAC therapy which is done by maximizing the distribution of doses in cervical cancer and minimizing the distribution of doses to the surrounding healthy organs namely bladder and rectum as they are important organs around the cervix that are at risk of being exposed to radiation or known as Organ at Risk (OAR).
“The effective dose is the radiation dose which takes into account the weight factor of the tissue subjected to radiation and the radiation weight factor from various sources of radiation. Each radiation source has a different radiation weight factor “, she explained.
Moreover, excessive doses to OAR will cause damage effects on the constituent tissue. Each OAR has its own dose of tolerance depending on the sensitivity of the organ’s constituent tissue.
“So, the accuracy of determining the dose is absolutely necessary for therapy using LINAC”, she explained.
In the end, Dr. Dyah also said that the radiation dose for bladder and rectum should not exceed the dose tolerance. So, she continued, the dose of the bladder and rectum can be evaluated by looking at the dose of both Dose Volume Histogram (DVH) bladder and rectum 2cc (D2cc).
Author: Asthesia Dhea Cantika
Editor : Khefti Al Mawalia
Reference:
Suryani Astuti, Nurul Fitriyah, Gege Ayu Listya, Bambang Haris Suhartono. 2018. Brachytherapy Treatment Planning and Linac for Dose Measurement of Bladder and Rectum in Cervical Cancer Patients. Conference: 2018 3rd International Seminar on Sensors, Instrumentation, Measurement and Metrology (ISSIMM)
