radiation oncology

rad. oncology is one of…

three principal modalities used in cancer treatment, alongside chemo and surgery

tumors are treated with ___ doses of ionizing radiation

cancericidial

goals of radiation oncology

to deliver cancericidial dose to tumor but limit dose to normal, noncancerous tissues

cancer treatment planning requires a multidisciplinary approach, alongs with a compilation of which diagnostic testing to be effective?

ct, radiographs, sonography, biopsy results, pathology reports

treatment planning involves consultation between…

surgical oncologists, radiation oncologists, medical oncologists

external beam therapy

patient lies under machine that emits radiation

brachytherapy

technique in which radioactive material is placed within patient

brachytherapy consists of a series of ___ radiation over ___ period to relatively small volume of tissue

low intensity rad, extended period

bracytherapy tends to be…

temporary, as radiation sources left in patient until designated tumor has been attained

low dose rate (LDR)

patient hospitalized for 3-4 days

high dose rate (HDR)

high activity isotope, allows dose to be delivered over a few minutes, allowing treatment to take place on an outpatient basis

permanent implant

nuclides with half life of hours or days are left in patient essentially forever

what are the different strengths that radiation oncology units are available in

120 kVp superficial, 250 kVp orthovoltage, cobalt-60 gamma ray, 6-MV-35-MV linear accelerator

6-MV-35-MV linear accelerator

source of high energy (megavoltage) electrons and xrays

two types of linear accelerators

single photon energy, dual photon energy

dual photon energy machine

consists of one low energy and one high energy beam for treating tumors in thinner/thicker parts of the body

multileaf collimation

beam defining system; computer software system determines how multileaf collimator will be used to shape radiation fields and shield normal tissue from beam

steps for linear accelerator

simulation, dosimetry, treatment

simulator

diagnostic xray machine that has some geometric and physical characteristics as a treatment unit

radiation oncology uses what to find the tumor’s precise location?

CT/MRI to determine tumor’s location and design a treatment plan

immobilization devices

position patient in manner that is stable and reproducible

dosimetry

measurement of rad dose, demonstrates how radiation is distributed or attenuated throughout the patient’s body

some organs are more ___ or ___ than others

radiosensitive, radioresistant

kidneys are highly radiosensitive, so a higher dose of ___ can cause fatal radiation nephritis

2500 cGy

dosimetrist attempts to eliminate…

hot spots

to avoid hot spots, wedge filters can

be used to absorb some beam h

hot spots can be avoided by changing…

weighting of radiation beams

rad therapist skills

-positions patient and aligns skin marks according to plan

-interpret prescription from rad onc.

-record administration of rad/cumulative dose

-implement changes in plan

-monitors pt well being

-assists in side-effect management

general side effects

fatigue, skin problems, hair loss, low blood counts

head/neck side effects

headaches, dry mouth, mouth/gum sores, swallowing difficulties, nausea, hair loss, skin/scalp changes, memory loss, taste changes

chest side effects

swallowing difficulty, SOB, cough, fever, rad fibrosis, breast soreness, lymphadema

abdomen side effects

appetite loss, diarrhea, bowel cramping, nausea/vomiting

pelvis side effects

bladder irritation, incontinence, low sperm count, rectal bleeding, diarrhea, female infertility, se. dysfunction

clinical applications

lung, prostate, oral cavity, cervical, hodgkin’s, breast, laryngeal, skin