Illustrated History of Radiology (X-Ray, CT, PET, MRI, Ultrasound) By Brian Nett, PhD / History In this post we present a brief history of Radiology equipment focusing on the major developments which lead to x-ray Radiography, CT, SPECT, PET and Ultrasound imaging.
The Filtered BackProjection (FBP) algorithm is the basis for image reconstruction (converting from the measured data to the image) on modern CT scanners. FBP is a fast and direct method to generate CT images. As the name suggests it is composed of two main steps filtering the data (along the row direction in the detector)
Filtered BackProjection (FBP) Illustrated Guide for Radiologic Technologists Read More »
If you are a student in training or totally new to x-ray physics are you feeling: overwhelmed or confused with the all the terminology and physics concepts pressured or embarrassed that you don’t know the answers to questions from senior technologists during your clinicals unsure of radiation effects and nervous about mass media coverage you
After the invention of CT itself and moving from first generation CT to third generation CT the incorporation of slip rings into modern CT is the most import enabler of improved scanning. It has enabled a number of clinical applications which were hypothesized when the Nobel Prize was granted for CT, but not possible until
Slip Ring CT pictorial guide [helical, cardiac, perfusion, 4DCT] Read More »
CT (Computed Tomography) scanning can be accomplished with multiple different scan modes which have different characteristics. Axial non-volumetric scanning is how CT began where one (or just a few) slices are acquired during each gantry rotation. Traditional helical scanning (some call spiral) has the advantage of being faster than non volumetric axial scanning and also
LET (Linear Energy Transfer), RBE (Relative Biological Effectiveness) and OER (Oxygen Enhancement Ratio) are important terms in radiation biology and relate to the relative damage that will occur with radiation under different circumstances. As LET increases there are more energetic electrons deposited closely together and thus damage to DNA is more likely. Therefore, even with
LET, RBE and OER (Oh My!). Radiologic Technologists Guide to 3 Radiation Biology Terms. Read More »
Radiation damage can be either acute or chronic depending on the conditions. Acute radiation effects are due to short exposures to radiation at a relatively high dose rates and the impact is observed within days or weeks (examples include acute radiation syndromes). Whereas chronic radiation effects are typically associated with lower doses and the effects
Radiation Carcinogenesis In this post we will describe the stochastic effect of radiation carcinogenesis (a fancy way of saying a higher risk of cancer induction after being exposed to ionizing radiation). The mechanism for carcinogenesis is primarily x-rays coming in, generating energetic electrons which then either directly or indirectly cause DNA damage. The data which
Radiation risks to germline cells (sperm and ova) include reduced fertility, and hereditary risks of increased mutation rate. These effects are dependent on the radiation dose: (males) [0.15-0.5 Gy] reduced sperm count, [0.5-6 Gy] temporary sterility, [greater 6 Gy] permanent sterility, and (females) [2-12 Gy depending on age] causes permanent sterility. Hereditary risks of increased
The acute radiation syndromes are cause by a sudden large dose of radiation to the body and depending upon the dose level one will experience either: Cerebral Vascular (a.k.a. CNS) Syndrome, Gastrointestinal (GI) syndrome, or hematopoietic (bone marrow) syndrome. This listed order is the order of severity and of the higher dose levels lead to
Acute Radiation Syndromes [ Hematopoietic, GI, CNS ] for Radiologic Technologists Read More »
