all right guys I am back with the line Focus principle here's another um concept that I think we're making bigger than it needs to be so really the line Focus principle is a super long name for comparing the size of the actual focal spot to the effective and it's just the relationship between the two your actual focal spot is where those electrons that are coming from your cathode end hit on the anode or your target sometimes it's called Target um so where the electrons hit uh or the focal track on the target is where your actual focal spot is the effective focal spot is what exits out the tube towards the patient so as the electrons are coming across where they hit here this area on the anode is your actual and then the effective focal spot is what exits out so some tips that I use is is um I go with the letters a lot so actual is at the anode effective exits the actual focal spot is always larger than the effective the anode angle can have an effect on where um on the size of your effective focal spot okay so the ano angle as it changes and if you watch the anode heel Effect one right it's either a smaller degree of angle or a larger degree of angle this can change the size of your effective focal spot so the image on the top here is showing you a larger anode angle with 24° and the bottom one is smaller with 12° and just like your anode heel effect concept the smaller anode angle makes it steeper the larger anode angle remember bring the heel back more opening up the space so a smaller anode angle makes it steeper up and down and it's going to decrease the size of the effective focal spot so because it's so steep up and down the size of your effective focal spot which is exiting out to your patient is going to be smaller if you increase anode angle making the angle degree larger moving it backwards it is going to have a larger effective focal spot okay so sort of an opposite concept there and then just a general term that I've seen come up a few times is this off focus radiation not necessarily that it's related to the line Focus principle um but it just sort of felt like I wanted to put it in here so we know that the actual focal spot is where the electrons hit on the anode itself that actual that focal track the off focus radiation um is radiation that's produced from rebounding electrons it originates outside of the anode focal spot so these off focal x-rays are outside the focal spot area so again you know just some terminology that's all relating to sort of this one spot on the anode where those electrons that are coming across hit actual focal spot is right here at the anode or the Target or the tuen anode the effective exits if radiation is produced outside of this focal track or this actual focal spot it is the off focus radiation okay so not a wild concept don't make it bigger than it needs to be and I just hope that was helpful