J Med Assoc Thai 2009; 92 (6):831

Views: 1,431 | Downloads: 118 | Responses: 0

PDF XML Respond to this article Print Alert & updates Request permissions Email to a friend


Evaluation of Image Quality and Lens’s Radiation Dose of a Low-Dose Cranial CT Scan
Chiewvit P Mail, Ananwattanasuk J , Mongkolsuk M , Boonma C , Suthipongchai S

Objective: To determine the lowest miliampere-second (mAs) of a cranial computed tomography (CT) scan
that can maintain acceptable image quality on cranial CT scan which might help reducing the risk of cataract
formation.

Material and Method: The present study was performed on the 148 patients in routine daily practice sent for
diagnosis of intracranial conditions by a cranial CT scan. During the cranial CT scanning, each lens’s
radiation dose on patient’s eyes was measured by a thermoluminescent dosimeter. Clinical image quality,
particularly in analysis of gray and white matter differentiation, was evaluated independently using a 5 point
scale by two radiologists.

Results:
During standard cranial CT scan protocol with 250 miliampere-second (mAs), the total dose of left
and right lens’s dose were about 50.93 miligray (mGy) and 51.66 mGy, respectively. When applying low dose
cranial CT scan protocols by decreasing mAs to 200, 150 and 100 mAs, the total dose of right and left lens were
of 45.68 mGy and 46.04 mGy for 200 mAs, 34.65 mGy and 34.77 mGy for 150 mAs, 28.73 mGy and 29.25 mGy
for 100 mAs respectively.

Conclusion: A low dose cranial CT scan at 100 miliampere-second provides not only an acceptable clinical
image quality, but also decreases the lens’s radiation dose by 43%.

Keywords: Cataract, Face, Head, Lens, Crystalline, Radiation dosage, Skull, Tomography, X-ray computed

Download: PDF