Radiotherapy MCQs

In afterloading procedures, an unloaded applicator is inserted first and the radioactive sources are introduced later . Afterloading has been utilized in many recently described uterine applicators, but the radiation exposure of physicians, nurses, and visitors during the treatment remains a serious problem. In principle, complete elimination of all unnecessary radiation exposure is possible by 'remote after-loading ,' which has been used for small teleradium bombs for more than twenty-five years and is widely applied in industrial radiography with gamma-ray sources. KEY TAKEAWAY - In remote after loading radiation exposure to the surrounding tissue is reduced. Reference: Remote Afterloading with Intracavitary Applicators Ulrich K. Henschke, Basil S. Hilaris, and G.D. Mahan Radiology 1964 83:2, 344-345

10-DAY RULE: Radiological Investigations using Ionising Radiation in a female of reproductive age Group Should be Limited to first Ten Days Of Menstrual Cycle to avoid injury to any undiagnosed pregnancy.

Double-stranded breaks of nuclear DNA is the most important cellular effect of radiation. in clinical therapy,radiation damage is most commonly indirectly ionizing via free-radical intermediaries formed from the radiolysis of cellular water. Double standard DNA damage is most important step Reference : Mehta, SR & Suhag, Virender & Semwal, Manoj & Sharma, Neelam. (2010). Radiotherapy: Basic Concepts and Recent Advances. Medical Journal Armed Forces India. 66. 158-162. 10.1016/S0377-1237(10)80132-7 page 3

Intensity modulated radiation therapy is a state-of-the-art radiation delivery system, which shapes radiation beams to closely approximate the shape of the tumour This type of conformal radiation utilizes beams or multi leaf collimators that can turn on or off or be blocked during treatment, varying the radiation beam intensity across the targeted area Reference : Mehta, SR & Suhag, Virender & Semwal, Manoj & Sharma, Neelam. (2010). Radiotherapy: Basic Concepts and Recent Advances. Medical Journal Armed Forces India. 66. 158-162. 10.1016/S0377-1237(10)80132-7 page 9

Gross tumour volume (GTV) is all known gross disease including abnormally enlarged lymph nodes. The clinical target volume (CTV) encompasses the GTV plus regions considered to harbour potential microscopic disease. The planning target volume (PTV) provides a margin around the CTV to allow for variations in treatment setup and other anatomic motions during treatment such as respiration. In order to minimize any variation in patient positioning, meticulous immobilization is essential. Reference : Mehta, SR & Suhag, Virender & Semwal, Manoj & Sharma, Neelam. (2010). Radiotherapy: Basic Concepts and Recent Advances. Medical Journal Armed Forces India. 66. 158-162. 10.1016/S0377-1237(10)80132-7 page 5

Radionuclides used in PET scanning are typically isotopes with short half-lives such as carbon-11 (~20 min), nitrogen-13 (~10 min), oxygen-15 (~2 min),-CEREBRAL BLOOD FLOW TISSUE/TUMOR PERFUSION fluorine-18 (~110 min), gallium-68 (~67 min), rubidium-82 (~1.27 min)-MYOCARDIAL PERFUSION IMAGING UPTAKE BY MYOCARDIAL CELLS-it QUANTIFIES MYOCARDIAL BLOOD FLOW SIMILAR TO THALLIUM Gallium-68 (Ga-68) Dotatate (DOTA-0-Tyr3-Octreotate)- Ga-68-labeled somatostatin receptor positron emission tomography (PET) imaging agents FOR NEUROENDOCRINE TUMORS Lutecium-177 (Lu-177) Dotatate (Lutathera) Therapy for Neuroendocrine Tumors As an alternative to Yttrium-90

Signs of pneumomediastinum Continuous Diaphgram Sign Spinnaker Sign/Angel Wing Sign Tubular artery sign Ring around artery sign Double bronchial wall sign subcutaneous emphysema gas around pulmonary artery and main branches: ring around artery sign gas outlining major aortic branches: tubular artery sign gas outlining bronchial wall: double bronchial wall sign continuous diaphragm sign: due to gas trapped posterior to pericardium gas between parietal pleura and diaphragm: extrapleural sign gas in pulmonary ligament Naclerios V sign Paediatric pneumomediastinum : elevated thymus: thymic wing sign gas crossing the superior mediastinum: haystack sign radiotherapy

Explanation: LINACs produce both X-rays and electrons , making them versatile for treating different tumor sites. A Linear Accelerator (LINAC) is the most widely used machine for external beam radiotherapy. It works by accelerating electrons at high speed and then using them in two ways: The electrons themselves can be used directly for treatment. Or they can be made to strike a target, producing high-energy X-rays . These X-rays or electrons are then shaped and directed precisely at the patient's tumour to destroy cancer cells while minimising damage to surrounding healthy tissue. LINACs can deliver radiation using modern techniques like IMRT, VMAT, IGRT, SRS, and SBRT . Reference: https://barc.gov.in/ebooks/9788195473359/paper29.pdf https://med.virginia.edu/radiation-oncology/about/advanced-technologies/linear-accelerator-treatments/