Cellular Effects of Radiation :Cellular Effects of Radiation Linear Nonthreshold Dose Response


Introduction :Introduction Radiobiologists were conducting research to have a similar result in radiation and dose- response relationship. This result is needed so it can be used to predict the risk of malignancy in human populations that have been exposed to low levels of ionizing radiation or Low LET radiation. Dose- response relationship is also called the dose- response curves which are graph or maps relationship between observed effects (response) from radiation and dose of radiation received by the patient.


Dose Response Curves :Dose Response Curves Dose- response curves differ in two ways: they are either linear or nonlinear. they are either threshold or nonthreshold. Linear Nonthreshold Curve Linear Threshold Curve Linear Quadratic Curve


Dose Response Relationship :Dose Response Relationship Linear means that an observed response is directly proportional to the dose. Example: Doubling the dose of radiation would double the response Nonlinear means that an observed response is not directly proportional to the dose. Example: Doubling the dose of radiation does not double the response


Dose Response Relationship :Dose Response Relationship Threshold assumes that there is a radiation level reached below which there would be no effects observed. Nonthreshold assumes that any radiation dose produces an effect. Linear Quadratic Dose Response Linear Nonthreshold Dose Response Linear Threshold Dose Response Nonlinear Dose Response (sigmoid curve)


Linear Nonthreshold Dose Response :Linear Nonthreshold Dose Response A Linear nonthreshold dose response means that any radiation dose will produce a biologic effect. No radiation dose is believed to be absolutely “safe”. Diagnostic radiology is primarily concerned with linear nonthreshold dose response relationship. Hypothesis of LNDR is basis for setting radiation- protection standards worldwide.


Linear Nonthreshold Dose Response :Linear Nonthreshold Dose Response Stochastic (probabilistic) Health Effects are effects that which is occur by chance, generally occurring without a threshold level of dose. Leukemia, breast cancer, and other genetic damage are believed to follow the linear nonthreshold dose response relationship.


Linear Nonthreshold Dose Response :Linear Nonthreshold Dose Response The principal basis for the LNDR is theoretical, and very simple. A single particle of radiation hitting a single DNA molecule in a single cell nucleus of a human body can initiate a cancer (direct action). Direct Action Effect


Factors Effecting the Dose Models and Theories :Factors Effecting the Dose Models and Theories The time period over which the dose is delivered Age of the exposed individual State of health of the exposed individual The time period between multiple exposures


Conclusion :Conclusion People misunderstand everything about low level radiation if it’s safe or not. Public are scared having an x-ray procedure or nuclear scan when radiation is mentioned. Everybody in mind is cancer producing ray that will hit and absorb their body, that there are factors to consider for the biological damage happen.


Questions :Questions 1. ________ which are graph or maps relationship between observed effects (response) from radiation and dose of radiation received by the patient. Answer: Dose Response Relationship Curve 2. Dose Response Curve differ in two ways, what are they? Answer: They are either linear or nonlinear and they are either threshold or nonthreshold. 3. List the 4 Dose Response Relationship Curve. Answer: Linear Quadratic Dose Response,Linear Nonthreshold Dose Response,Linear Threshold Dose Response,and Nonlinear Dose Response (sigmoid curve) 4. No radiation dose is believed to be absolutely ______. Answer: Safe 5. Identify Linear Nonthreshold Dose Response Curve in the picture. Answer: Line B