Lec 06 Radiation Oncology Flashcards
What is the difference between Ionizing and Non-ionizing radiation?
Ionizing radiation carries enough energy to remove and electron from an atom
What are the two types of Ionizing radiation?
particulate and EM
What is the primary target of radiotherapy?
DNA
In general, cells are most radiosensitive during which phases of the cell cycle?
M and G2 phases
In general, cells are most resistant to radiotherapy during which phase of the cell cycle?
late S phase
What is the difference between the direct and indirect action of radiation?
Direct - radiation causes damage by interacting with the chemical bonds of DNA
Indirect - radiation interacts with water, causing the formation of hydroxyl radicals which cause the actual DNA damage
What are the steps in the radiation oncology process?
- consultation
- simulation
- treatment/planning
- radiation therapy
- follow up
What is the purpose of a thermoplastic mask/mesh?
stabilization of the head during radiotherapy
What are the two emergencies in radio oncology?
- superior vena cava syndrome
2. cord compression
What are the two types of imaging simulations?
conventional (X-ray), CT simulation
What is target volume?
volume that the radiation oncologist has defined to receive the prescribed dosage of radiotherapy
What is treated volume?
volume encompassed by a clinically significant isodose surface/line (usually 95%)
What is irradiated volume?
volume that corresponds to a dose relevant to the normal tissues that surround the target volume
What are the different types of treatment planning?
Conventional - 2D based approach using a calibrated fluoroscopy machine that simulates the beam characteristics of a linear accelerator
Conformal - beams are modified to conform to the shape of the target based on information from the CT simulation
3D CRT Intensity Modulated RT (IMRT) - CT images used to contour target and normal structure, dose to the tumor and organs at risk can be calculated
How often should post-therapy check-ups be done?
weekly
