Dose reduction vs Attenuation of Dose Effectiveness

There is no “versus”.  Dose and dose effectiveness always co-exist and either can be modified.    Shielding is another matter and presents as another variable. Dose can be increased or decreased by modifying shielding factors.  Some shielding considerations include type of radiation, energy of radiation and the generation of Bremsstrahlung radiation within the shielding. This occurs when high energy radiation interacts with the shielding.  This additional radiation must then be shielded against. https://en.wikipedia.org/wiki/Bremsstrahlung

The following is an opinion piece.  Dr. Nick reckons I shouldn’t know this stuff.  He prefers meritocracy.  I prefer democracy.  There is no “versus”.   I might be wrong, he might be wrong.  Research it independently.

Expected results from any radiological setting can be modified by:

a. modifying dose eg, by reducing dose, or

b. by modifying the biological effectiveness of any given dose.  eg by reducing oxygen tension within the test subject’s cells. This effect actually presents a major challenge in oncology. As the blood supply to tumor cells reduces due to prior radiation treatment doses, the effectiveness of each dose within the target cells reduces because oxygen is an important component of dose effectiveness.  This at the present time is being researched.  Various solutions to the problem are being researched.  Some of them look at ways of achieving heightened oxygen tension within the target cells and tissues. The would regain some of the lost dose effectiveness.

It is a principle which may be imagined if one visualizes a hike up Mt Everest.  At altitude the state of oxygen tension in the cells may reduce, due to the physics of breathing. (the oxygen ratio in air remains the same at altitude, but it becomes harder and harder to inhale sufficient air the higher up one goes. Long before the summit of Everest, the climber has to use pressure tanks of air or oxygen.

The matter of dose effectiveness being modified by the condition or state of the organism  is most interesting.  Hiroshima doctors observed certain important things in these regards in the aftermath of the Hiroshima bombing, as the following quotation shows:

“Whatever its source, the disease had some baffling quirks. Not all the patients exhibited all the main symptoms. People who suffered flash burns were protected, to a considerable extent, from radiation sickness. Those who had lain quietly for days or even hours after the bombing were much less liable to get sick than those who had been active.” Source:  John Hersey, Hiroshima,   IV – Panic Grass and Feverfew,  The New Yorker, August 31, 1946  now online at http://www.newyorker.com/magazine/1946/08/31/hiroshima?intcid=mod-most-popular.  The Hiroshima doctors informed Hersey of the facts of the atomic bomb disease at that time.

Of course, it is predictable what the school of hormesis claims of this. Firstly, in the local experiments here in South Australia there is no mention of dose effect moderator factors.

The example of the hormesis view of climbing a mounting is another case in point.

For as one climbs, cosmic background, including exposure to cosmic rays and barium isotopes (created by the interaction of cosmic rays with the atmosphere) increases.

However as one climbs, the harder it becomes to fill one’s lungs.  The higher one goes, the less effective the increasing dose becomes.  Tibetans and Andean people have adaptations which allow further protections. Some Tibetan and Chinese mountain dweller use oxygen far more sparingly than other people in their cells.

We have seen that US Nuclear submariners enjoy a very low annual exposure to radiation.  We have seen how oxygen is a dose effectiveness moderator. The higher the oxygen tension in the cell, the more damage radiation tracking through that cell can do.  The lower the oxygen tension in the cell, the less effective any dose of radiation tracking through the cell will be.  There are many variables.

 

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What happens to dose effectiveness when a climber dons an air tank?  Dose Effectiveness has an upward moderator goes up.

What happens to dose effectiveness as the voyage of a submerged boat extends over time ? It would tend to downward.

 

 

 

 

 

 

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