Clover Learning's video: Anode Heel Effect X-Ray Tube

This video covers topics concerning the anode heel effect. The rest of the x-ray tube series can be found on our website www.radtechbootcamp.com. For more videos, quizzes, and ARRT Mock Exams! Decreasing the angle of the X-ray tube anode causes a variation of the beam’s intensity across the x-ray field. In other words, there are fewer x-ray photons on the anode side of the beam compared to the cathode side of the beam. X-ray photons are not simply created on the surface of the X-ray anode, but instead, are formed within the inner part of the anode’s target material. The X-ray photons that are created near the back of the anode must travel through more target material than those created closer to the anode's surface. Some of the X-ray photons passing through the back of the anode are absorbed into the anode, which acts to decrease the X-ray beam intensity on the anode side of the beam. By understanding the anode heel effect, we are able to use it to our advantage in producing high-quality radiographs. In this illustration, you can see that by placing the patient’s head closer to the anode end of the x-ray tube, we are able to use the stronger part of the bean to better penetrate the patient’s lumbar anatomy. A more noticeable and undesirable anode heel effect will occur when an anode angle is less than 15 degrees. This is, as discussed earlier, due to the increased percentage of X-ray photons having to travel through the material of the anode heel. The relationship between anode angle and anode heel effect is inversely related, in that as anode angle decreased, that is, it gets steeper, anode heel effect increases. An increase in anode heel effect can also be brought about by decreasing the source to image distance. By comparing the X-ray beam from SID 1 and SID 2, we can see that the image receptor closets to the beam would produce an image with a greater variation in both light and dark densities. By shortening the source to image distance, the image receptor is exposed to a greater amount of both high-intensity cathode side photons as well as the low-intensity anode side photons. When we begin to increase the source to image distance, that is, move it farther from the x-ray tube, the difference between photon intensities begins to also decrease. The relationship between SID and heel effect also has an inversely related since as SID decreased, heel effect increases. The size of the x-ray field can be another contributing factor to the severity of the heel effect. As the x-ray beam diverges outward, the differences in beam intensity increase. A large field size will produce greater variation in both high and low-intensity photons, compared to a smaller field size. The relationship between field size and heel effect is directly related to that as field size increases, so does the heel effect. Please visit us at www.radtechbootcamp.com to see many more videos like this!