Showing posts with label X-ray. Show all posts
Showing posts with label X-ray. Show all posts
4/04/2012
X-ray: Pneumomediastinum vs. Pneumopericardium
Look for the air crossing the midline between cardiac silhouette and diaphragm as the distinction between the two conditions. Of course, there are always some exceptions.
3/18/2011
CXR: Pericardial effusion & ...after (partial) pericardiocentesis (Hydropneumopericardium)
"Money bag" appearance on CXR
Hydropneumopericardium
3/09/2011
3/07/2011
10/05/2010
EKG: Low Voltage Complexes & Lead Misplacement
Low voltage complexes. Cause of this is evident in the CXR below.
What is the P wave axis? What will be the diagnosis for the unusual P wave axis?
If unusual P wave axis were to be due to misplacement of leads, which leads were misplaced?
If certain leads were misplaced...what would be the QRS axis, if the misplaced leads were
What is the P wave axis? What will be the diagnosis for the unusual P wave axis?
If unusual P wave axis were to be due to misplacement of leads, which leads were misplaced?
If certain leads were misplaced...what would be the QRS axis, if the misplaced leads were
7/20/2010
Cath: X-ray
(Extract from Morton Kern’s The Cardiac Catheterization Handbook. 3rd edition 1999)
X-ray tube: converts electrical energy into X-ray beam. Electron beams from a heated cathode are accelerated towards the rotating disc of anode. The electrons become X-rays upon contact with anode. But, only 0.2-0.6% of electrical energy provided is eventually converted into X-ray. This process generates extreme heat.
Three factors influence the X-ray image:
1) Electrical current (mA): Number of photons (electrical particles) generated per second. Increasing milliamperage increases quality of image. But, heat generated is the limiting factor. Of course, this increases radiation exposure to patient and increases scatter – leading to increase in exposure to lab personnel.
2) Kilovoltage level (kV): The wavelength of the X-ray beam. Higher the kV, shorter is the wavelength. Less tissue penetration. So, for obese patients, high kV is needed to get adequate penetration. But, high kV leads to poor resolution of the image. Higher kV also increases scatter and therefore, higher exposure to lab personnel.
High kV - short wavelength, uniform and better penetration. But, low contrast in image.
Low kV - provides better contrast in image.
High kV allows to keep mA low, but the trade-off is low-contrast in the image. A balance has to be struck. kV has more effect on image contrast than mA.
X-ray tube: converts electrical energy into X-ray beam. Electron beams from a heated cathode are accelerated towards the rotating disc of anode. The electrons become X-rays upon contact with anode. But, only 0.2-0.6% of electrical energy provided is eventually converted into X-ray. This process generates extreme heat.
Three factors influence the X-ray image:
1) Electrical current (mA): Number of photons (electrical particles) generated per second. Increasing milliamperage increases quality of image. But, heat generated is the limiting factor. Of course, this increases radiation exposure to patient and increases scatter – leading to increase in exposure to lab personnel.
2) Kilovoltage level (kV): The wavelength of the X-ray beam. Higher the kV, shorter is the wavelength. Less tissue penetration. So, for obese patients, high kV is needed to get adequate penetration. But, high kV leads to poor resolution of the image. Higher kV also increases scatter and therefore, higher exposure to lab personnel.
High kV - short wavelength, uniform and better penetration. But, low contrast in image.
Low kV - provides better contrast in image.
High kV allows to keep mA low, but the trade-off is low-contrast in the image. A balance has to be struck. kV has more effect on image contrast than mA.
3) Exposure Time (s): Pulse width
6/03/2010
Anatomy: Aberrant RSCA, Pulmonary Sling, Barium Swallow
Aberrant Subclavian Artery Origin
(RSCA crosses midline, posterior to esophagus)
Netter diagram
Pulmonary Sling: Origin of LPA from RPA
(LPA crosses midline anterior to esophagus, inbetween esophagus & trachea)
(Diagrams below are from Esophagography in Anomalies of Aortic Arch System. A.C. Klinkhamer. The Williams & Wilkins Company, Baltimore MD. 1996)
How to use the Table:
1. First, review plain CXR (PA view; High dose film) - Ascertain aortic arch sidedness & position of descending aorta in thorax.
2. Second, study Barium Swallow Study - Usually Frontal and Oblique views (Note: Lateral view is ideal for Pulmonary sling and Double aortic arch, but not useful in other anomalies)
Image source: Esophagography in anomalies of the aortic arch system. A.C. Klinkhamer. The Williams & Wilkins Company, Baltimore, MD. 1969. Copyright - Excerpta Medica Foundation.
Related link: Barium Swallow
1/21/2010
LV Non-Compaction by Angiogram
4 wk old; Presented with arrhythmia, Circulatory shock and respiratory distress.
Images from Hughes et al. Cardiology in the Young 2007;17:56-63
See also the other posting on this subject.
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