[Absorbed dose and the effective dose of panoramic temporo mandibular joint radiography].
OBJECTIVE
This study measured the radiation doses absorbed by the patient during Panoramic temporo mandibular joint radiography (Panoramic TMJ), Schüllers method and Orbitoramus projection. The dose of the frontal view in Panoramic TMJ was compared to that with Orbitoramus projection and the lateral view in Panoramic TMJ was compared to that with Schüllers method.


METHODS
We measured the doses received by various organs and calculated the effective doses using the guidelines of the International Commission on Radiological Protection in Publication 103. Organ absorbed doses were measured using an anthropomorphic phantom, loaded with thermoluminescent dosimeters (TLD), located at 160 sensitive sites. The dose shows the sum value of irradiation on both the right and left sides. In addition, we set a few different exposure field sizes.


RESULTS
The effective dose for a frontal view in Panoramic TMJ was 11 µSv, and that for the lateral view was 14 µSv.


CONCLUSIONS
The lens of the Orbitoramus projection was 40 times higher than the frontal view in Panoramic TMJ. Although the effective dose of the lateral view in Panoramic TMJ was 3 times higher than that of the small exposure field (10×10 cm on film) in Schüller's method, it was the same as that of a mid-sized exposure field. When the exposure field in the inferior 1/3 was reduced during panoramic TMJ, the effective doses could be decreased. Therefore we recommend that the size of the exposure field in Panoramic TMJ be decreased.
Division of Radiological Technology, Aichi-Gakuin University Dental Hospital.
Ayae
A
Matsuo
Tsuneichi
T
Okano
Kenichi
K
Gotoh
Midori
M
Yokoi
Akiko
A
Hirukawa
Shinji
S
Okumura
Syuji
S
Koyama
D006801:Humans; D019047:Phantoms, Imaging; D011829:Radiation Dosage; D011862:Radiography, Panoramic / Q000379:methods*; D013704:Temporomandibular Joint / Q000000981:diagnostic imaging*