CHAPTER 2 Ra d ia tio n Ph ys ics Tubehead The x-ray tubehead is a tightly sealed, heavy metal housing that contains the x-ray tube that produces dental x-rays. The component parts of the tubehead include the following (Figure 2-12):
B
13
• Metal housing, or the metal body of the tubehead that surrounds the x-ray tube and transformers and is lled with oil—protects the x-ray tube and grounds the high-voltage components. • Insulating oil, or the oil that surrounds the x-ray tube and transformers inside the tubehead— prevents overheating by absorbing the heat created by the production of x-rays. • Tubehead seal, or the aluminum or leaded-glass covering of the tubehead that permits the exit of x-rays from the tubehead—seals the oil in the tubehead and acts as a lter to the x-ray beam. • X-ray tube, or the heart of the x-ray generating system (discussed later) (Figure 2-13).
C
A
FIG 2-11 Thre e com pone nt parts of de ntal x-ray m achine : A, control pane l; B, e xte ns ion arm ; C, tube he ad. (Courte s y Planm e ca, Inc., Ros e lle , IL.)
FIG 2-13 Actual de ntal x-ray tube . (From White SC, Pharoah MJ : Oral radiology: principle s and inte rpre tation, e d 7, St. Louis , 2014, Mos by.)
X-ra y tube
S te p-up tra ns forme r Ca thode ( )
Me ta l hous ing of x-ra y tube he a d
S te p-down tra ns forme r
Anode ( )
Fila me nt circuit
Tube he a d seal
Ins ula ting oil
Aluminum dis ks
Le a d collima tor
Unle a de d gla s s window of x-ra y tube
P os ition-indica ting de vice
FIG 2-12 Diagram of de ntal x-ray tube he ad.