Aims and objectives
Pediatric CT examination plays an important role in the diagnosis of pediatric patients,
and establishment of intervention management.
However,
the most serious drawback of CT is radiation exposure- which leads to an increased risk of cancer1-4).
Because pediatric patients' radiosensitivity is much higher than that of the adult patient,
from our understanding when performing the same protocol on CT exams,
doses 3 to 5 times greater than the exposures to adults are administered to the sensitive young patients5).
ALARA advocates strict efforts to reduce these...
Methods and materials
CT Scanning
All CT scans were performed on a 64-detector row CT scanner (Lightspeed VCT; GE Healthcare,
Milwaukee,
Wisconsin).
Dose measurement to investigate the shape of the bowtie filters :
The scanning parameters were as follows: scan mode,
helical scan; beam width,
20.0 mm; section thickness,
0.625 mm; pitch factor,
0.531 mm/rotation; gantry rotation time,
1.0 seconds; detector collimation,
64×0.625 mm; Tube voltage.
80-,
100-,
120-,
and 140 kVp; Tube current set on 10mA~200mA (keeping 9.5 mGy in CTDIvol); matrix size,
512×512; Beam bowtie filter,...
Results
Dose measurement to investigate the shape of the bowtie filters
The result of each tube voltage when small bowtie filter is used is shown.
The radiation dose at the ISO center was 4.95 mGy at 80 kVp,
4.10 mGy at 100 kVp,
3.75 mGy at 120 kVp,
3.52 mGy at 140 kVp,
and the maximum dose of each tube voltage was shown.
The radiation dose at 14 cm from the ISO center was 0.65 mGy at 80 kVp,
0.65 mGy at 100 kVp,
0.68 mGy...
Conclusion
As we know,
using lower tube voltage,
it is necessary to select the optimal bowtie filter.
Our results show that the radiation dose at 80 kVp in all bowtie filters was significantly higher than at 100 kVp,
120 kVp,
and 140 kVp.
And it shows that the radiation dose at small bowtie filter in all tube voltages was significantly higher than at middle bowtie filter and large bowtie filter.
If bowtie filter's material is the same,
the small bowtie filter is thin than the other...
Personal information
Takayuki Oku,
radiological technologist,
Tsuchiya general hospital,
Hiroshima,
Japan
Tsuchiya General Hospital
3-30 Nakajima-cyou Naka-ku Hiroshima Japan
Phone: + 81822439191
Fax: + 81822411865
E-mail
[email protected]
Takanori Masuda,
radiological technologist,
Tsuchiya general hospital,
Hiroshima,
Japan
Naoyuki Imada,
radiological technologist,
Tsuchiya general hospital,
Hiroshima,
Japan
Yoriaki Matsumoto,
radiological technologist,
Tsuchiya general hospital,
Hiroshima,
Japan
Yukari yamashita,
radiological technologist,
Tsuchiya general hospital,
Hiroshima,
Japan
Masato Yoshida,
radiological technologist,
Tsuchiya general hospital,
Hiroshima,
Japan
References
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Chen MC,
Jan SL,
Wang CC,
Fu YC,
Lin PC,
et al.
Neonatal cardiac multidetector row CT: Why and how we do it.
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2008;38:438-51.
[2]Kalra MK,
Maher MM,
Toth TL,
Hamberg LM,
Blake MA,
Shepard JA,
et al.
Strategies for CT radiation dose optimization.
Radiology 2004;230:619-28.
[3]Frush DP,
Herlong JR.
Pediatric thoracic CT angiography.
Pediatr Radiol.
2005;35:11-25.
[4] Estay C,
Simian D,
Lubascher J,
Figueroa C,
O'Brien A,
Quera R.
Ionizing radiation exposure in patients with inflammatory bowel disease: Are...