Radiation Therapy Lecture Powerpoint Flashcards
Radiation therapy definition
Cancer treatment that uses high doses of radiation to kill cancer cells and stop them from spreading, up to 1/2 of cancer patients receive it at some point, can be used alone or alongside surgery or chemo
Photons energy rating scale
- Gamma rays
- x rays
- uv
- visible
- infared
- radio
Radiation therapy mech of action
Damages DNA directly or creates free radicals in cell that damage DNA of both cancer cells resulting in their death as well as host cells
Radiation can be both used as curative therapy as well as…
….palliative care
Preoperative radiation is known as ___, during surgery is ____, and post op therapy is ____
neoadjuvant, intraoperative, adjuvant
Considerations made in a radiation oncologist’s plan (therapeutic ratio) include (5)
- type of cancer
- size and location
- how close to normal tissue it is
- how far into the body it needs to travel
- age
Measure of radiation energy absorbed by 1kg of human tissue is a…
…gray (Gy)
Tattoo/body molds/mask use by radiation therapist
Ensure a patient is in correct position throughout treatment, permanent markings in the case of tattoos and potentially claustrophobic in the case of masks
Brachytherapy
Internal radiation where radioactive material is placed in the body near cancer cells typically in seeds
Systemic radiation
A radioactive substance is given by mouth or vein and travels into the blood to tissues thru the body
3D conformational radiation therapy (3D-CRT)
Most common type of external radiation therapy, computer software allows delivery at precisely shaped areas
Intensity modulated radiation therapy (IMRT)
A type of external radiation therapy that allows for different areas of a tumor or space nearby to receive varying doses of radiation allowing for less side effects than 3D-CRT
Gamma knife/stereotactic radiosurgery
A device for external radiation therapy for small tumors of the brain with well defined edges
Cyberknife/sterotactic body radiation therapy
A device for external radiation therapy of small tumors outside the brain and spinal cord
Total body irradation
Most commonly used for hematopoietic cell transplantation for leukemias and lymphomas, used as part of cytoreductive regimen
Proton therapy vs Electron therapy
Proton deposited energy is mostly delivered at the end of the path and less along the way (go thru tissue and not effect it until hitting the target tissue)
Electron beams can be used on superficial tumors (skin or surface of breast) that cannot travel very far thru tissue
Internal radiation therapy can be temporary or…
…permanent
During permanent brachytherapy, it is advised to limit contact with children and pregnant women because…
….the patient is slightly radioactive despite the amount reaching the skin is minimal
Zevalin
A monoclonal antibiody with radioactive substance bound to it used in treatment of B cell non hodgkin lymphoma to bind a protein found on surface of B lymphocytes
Often radiation therapy is given multiple times a week 2 treatments a day. Why?
Smaller doses minimize damage to normal tissue and by varying the time we increase chances the cells are being exposed at critical time of cell cycle when they are vulnerable to DNA damage
What stage of cell cylce are cells most radiosensitive? What is least?
G2 and M are most, S is least
Some cancers are very susceptible to radiation, while some are….
….radioresistant
Radiation acute side effects (5, one important one to note)
- diarrhea
- hair loss
- sexual changes
- fatigue
- VERY DEPENDENT on location of the treatment
Radiation chronic side effects (5)
- fibrosis and limited movement
- memory loss
- infertility
- mouth problems
- 2ndary cancers in children or adolescents
Radiation pneumonitis
A condition occurring 4-12 weeks after chest radiation (lung, breast, mediastinal) that presents with cough, dyspnea, chest pain, low grade fever that can be treated with steroids but can cause lung fibrosis
Radiosensitizers and radioprotectors (and an example of each)
- Drugs that make the cancer cells more sensitive to radiation therapy, developing field such as cisplatin
- Protect normal cells from damage caused by radiation therapy in areas where it is hard not to expose vital tissues to radiation such as amifostine
