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Exposure Factors
Chapter 17 - Lecture - patient as a beam emittor - Attenuation
| Question | Answer |
|---|---|
| How does atomic number affect attenuation? | Higher atomic number materials attenuate a greater percentage of the beam than low atomic number materials |
| How does tissue density affect attenuation? | The denser the absorbing material, the greater the attenuation |
| What elements are the human body mainly comprised of? | Hydrogen, Carbon, Nitrogen, and Oxygen |
| What are the differences between air, fat, muscle and bone with respect to their attenuation and the resultant image? | Attenuates radiation least to most: Air, fat, muscle, and then bone Image Receptor exposure least to greatest: Bone, muscle, fat, and the air |
| Why do some pathological conditions affect the attenuation of the x-ray beam? | Certain conditions can increase or decrease tissue thickness, or alter tissue composition → in return affects the degree of radiation absorption (attenuation) |
| How does an additive disease affect attenuation? | Additive disease causes increase in thickness, atomic number, and/or tissue density = greater attenuation of the x-ray beam |
| How does a destructive disease affect attenuation? | Destructive disease causes decrease in thickness, atomic number, and/or tissue density = less attenuation of the x-ray beam |
| Is Edema additive or destructive and does it increase or decrease attenuation? | Additive; increase in tissue thickness which equals greater attenuation and less image receptor exposure |
| Is congestive heart failure additive or destructive and does it increase or decrease attenuation? | Additive; Lung tissue density is increased and heart is enlarged which equals greater attenuation and less image receptor exposure |
| Is pneumonia additive or destructive and does it increase or decrease attenuation? | Additive; Inflammation of lung tissue causes fluid to fill alveolar spaces which has a greater tissue density than normal air present which equals greater attenuation and less image exposure |
| Is ascites additive or destructive and does it increase or decrease attenuation? | Additive; fluid accumulation within the peritoneal cavity causes an increase in tissue thickness which equals greater attenuation and less image receptor exposure |
| Is Paget's disease additive or destructive and does it increase or decrease attenuation? | Additive; an increase in bone cell activity which results in new bone growth results in an increase in bone thickness which equals greater attenuation and less image receptor exposure |
| Is atrophy additive or destructive and does it increase or decrease attenuation? | Destructive; diminished body tissue resulting in reduced thickness of part/body equals less attenuation and greater image receptor exposure |
| Is emphysema additive or destructive and does it increase or decrease attenuation? | Destructive; the overdistention of lung tissues by air results in a decrease in lung tissue density which equals less attenuation and greater image receptor exposure |
| Is a pneumothorax additive or destructive and does it increase or decrease attenuation? | Destructive; free air in pleural cavity displaces normal lung tissue and results in decreased density which equals less attenuation and greater image receptor exposure |
| Is degenerative arthritis additive or destructive and does it increase or decrease attenuation? | Destructive; inflammation of joints results in a destruction of adjoining bone tissue and decreases composition of the part which equals less attenuation and greater image receptor exposure |
| Is osteoporosis additive or destructive and does it increase or decrease attenuation? | Destructive; the defect in bone production causes a decreased composition of bone which equals less attenuation and greater image receptor exposure |
| The reduction in the total number of x-ray photons remaining in the beam after passing through a given thickness of material | Attenuation |
| The thicker the body part being radiographed, the ______ the attenuation will be | greater |
| In order to provide a sufficient number of x-ray photons for interaction with the image receptor, what must be done to the original quantity and quality of the photons (technique) when you have increased body part thickness? | The original quantity and quality of the photons (technique) must be increased |
| As an x-ray beam passes through a patient, the beam is _________ | Attenuated |
| In the diagnostic x-ray range, attenuation is either the result of? | Absorption or Compton scattering |
| Do higher atomic-number materials attenuate a greater or lesser percentage of the beam than low-atomic-number materials? | Greater |
| Effective atomic number of Air | 7.78 |
| Effective atomic number of fat | 6.46 |
| Effective atomic number of water | 7.51 |
| Effective atomic number of muscle | 7.64 |
| Effective atomic number of bone | 12.31 |
| The quantity of matter per unit of volume measured in kilograms per cubic feet | Density |
| The study of diseases | Pathology |
| True or False? Fluid will absorb more radiation than air | True |
| A disease that causes the affected body tissue to decrease in thickness, effective atomic number, and/or tissue density which results in less attenuation of the x-ray beam is what kind of condition? | Destructive Condition |
| A disease that causes the affected body tissue to increase in thickness, effective atomic number, and/or tissue density, resulting in a greater attenuation of the x-ray beam, is what kind of condition? | Additive Condition |
| An encapsulated infection that increases tissue thickness and may alter composition, particularly in the lungs | Abscess |
| Swelling that causes an increase in tissue thickness and may alter composition if it occurs in the Lungs | Edema |
| An abnormal new growth in tissues that results in an increase in tissue thickness and may alter composition, particularly in the lungs or bones, or when calcification results | Tumor |
| A collapse of the lung resulting in airlessness of all or part of the Lung tissue | Atelectasis |
| The chronic dilatation of the bronchi resulting in peribronchial thickening and small areas of atelectasis which causes an increase in lung tissue density | Bronchiectasis |
| An enlargement of the Heart | Cardiomegaly |
| When the Heart is in failure and cardiac output is diminished, resulting in backward failure or increased venous congestion in the Lungs | Congestive Heart Failure |
| Pus in the Thoracic Cavity causing an increase in tissue density | Empyema |
| When the pleural cavity fills with either blood or serous fluid, displacing normal lung tissue | Pleural effusions (hemothorax or Hydrothorax) |
| The inhalation of dust particles which can cause fibrotic (scarring) changes | Pneumoconiosis |
| The removal of a lung | Pneumonectomy |
| Inflammation of the lung tissues causing fluid to fill in the alveolar spaces | Pneumonia |
| When fluid fills the Interstitial lung tissues and the alveoli | Pulmonary edema |
| A large dilatation of the aorta | Aortic aneurysm |
| Fluid accumulation within the peritoneal cavity | Ascites |
| Fibrotic changes in the liver which can cause the Liver to enlarge and ascites can result | Cirrhosis |
| An overgrowth of the hands, feet, face, and jaw as a result of hypersecretion of growth hormones in an adult | Acromegaly |
| A chronic bone infection | Chronic Osteomyelitis |
| A dilatation of the fluid-filled cerebral ventricles causes an enlargement of the head | Hydroceophalus |
| The spread of cancer to bone | Osteoblastic Metastases |
| A tumor arising in the bone | Osteochondroma |
| An increase that occurs in bone cell activity, which leads to new bone growth | Paget's Disease |
| An increase in hardening as a result of a chronic inflammation in bone | Sclerosis |
| A psychological eating disorder that results in an extreme weight loss | Anorexia Nervosa |
| A wasting away of body tissue with diminished cell proliferation | Atrophy |
| A generalized wasting away of body tissue | Emaciation |
| The overdistention of the lung tissues by air | Emphysema |
| Free air in the pleural cavity which displaces normal lung tissue | Pneumothorax |
| A psychological disorder resulting in abnormal swallowing of air | Aerophagia |
| An obstruction in the bowel results in the abnormal accumulation of air and fluid | Bowel obstruction |
| Death of bone tissue | Aseptic Necrosis |
| Inflammation of the joints resulting in a destruction of adjoining bone tissue | Degenerative Arthritis |
Created by:
teresachristensen
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