1. Welcome!
Emission Spectra
Emission Spectra

2. Line and Continuous Spectra
Line represents characteristic, continuous represents Brems.
Lower energy beam
Higher energy beam
The ***x ray emission spectra are graphic depictions of the quantity (intensity) and quality (energy) of x ray photons produced during an x ray exposure. There are ***two different spectra, the line or discrete spectrum represents the characteristic rays and the continuous spectrum represents the Brems rays. The height of either or both denotes the number of photons produced during the exposure, while a shift of any part of either spectrum to the left or right denotes a change in the energy of the photons. A ***shift to the left would be a lower energy beam and a ***shift to the right would be a higher energy beam.
Line and Continuous Spectra

3. Increasing mA only increases amplitude.
mAs only changes the quantity or intensity of an x ray beam. It doesn’t change the quality of it; therefore, the spectrum will only show changes in amplitude. You’ll notice on the spectrum shown here that increasing mA only increases amplitude.
Effect of mAs

4. Increasing kVp increases amplitude AND causes a shift to the right.
kVp changes the quantity and quality of the x ray beam. An ***increase in kVp will increase the number of photons produced and also produce higher energy photons. Note on the spectrum shown here that an increase in kVp ***increases the amplitude of the spectrum and also causes the spectrum to shift to the right. Both the peak amplitude and the highest energy levels shift to the right.
Effect of kVp

5. Note the differences between a filtered and unfiltered x ray beam.
***Filtration of an x ray beam is very important. Without filtration, the x ray beam would consist of mostly very low energy photons which serve no diagnostic purpose since they don’t have enough energy to reach the image receptor. ***They would just be absorbed into the patient’s first few inches of tissue, increasing the patient’s skin dose.
Filtration

6. More filtration means lower quantity and higher quality.
***Increasing the filtration of an x ray beam decreases the quantity, but increases the quality. It does this by removing low energy photons and thereby increasing the proportion of higher energy photons. This is why on this spectrum, you note a shift to the right of the low energy side of the continuous line spectrum as well as a decrease in amplitude.
Quantity and Quality

7. Images from: http://whs. wsd. wednet
Though the spectra aren’t something you can see or see the immediate effects of, you should understand them so as to be familiar with the influence of various factors on the x-ray beam.
Summary