ESTIMATION OF ORGAN DOSES AND EFFECTIVE DOSES BASED ON IN-PHANTOM DOSIMETRY FOR PAEDIATRIC DIAGNOSTIC CARDIAC CATHETERISATION.

The present study evaluated the organ doses, effective doses and conversion factors from the dose-area product to effective dose in pediatric diagnostic cardiac catheterization performed by in-phantom dosimetry and Monte Carlo simulation. The organ and effective doses in 5-y-olds during diagnostic cardiac catheterizations were evaluated using radiophotoluminescence glass dosemeters implanted into a pediatric anthropomorphic phantom and PCXMC software. The mean effective dose was 3.8 mSv (range: 1.8-7.5 mSv). The conversion factors from the dose-area product to effective dose were 0.9 and 1.6 mSv (Gy cm2)-1 for posteroanterior and lateral fluoroscopy, respectively, and 0.9 and 1.5 mSv (Gy cm2)-1 for posteroanterior and lateral cineangiography, respectively. Effective doses evaluated using the pediatric dosimetry system agreed with those obtained using PCXMC software within 12%. The dose data and conversion factors evaluated may guide the estimation of exposure doses in children undergoing diagnostic cardiac catheterization.

ESTIMATION OF ORGAN DOSES AND EFFECTIVE DOSES BASED ON IN-PHANTOM DOSIMETRY FOR INFANT DIAGNOSTIC CARDIAC CATHETERISATIONS WITH NOVEL X-RAY IMAGING TECHNOLOGY.

The present study evaluated the organ and effective doses in infant diagnostic cardiac catheterisation performed using a modern x-ray imaging unit by in-phantom dosimetry. In addition, conversion factors from dose-area product (DAP) to effective dose were determined. The organ and effective doses in 1-year old during diagnostic cardiac catheterisations were measured using radiophotoluminescence glass dosemeters implanted into an infant anthropomorphic phantom. The mean effective doses, evaluated according to the International Commission on Radiologic Protection Publication 103, were 4.0 mSv (range: 1.5-8.7 mSv). The conversion factors from DAP to effective dose were 2 and 3.5 mSv (Gy cm2)-1 for posteroanterior and lateral fluoroscopy, respectively, and 1.8 and 3.3 mSv (Gy cm2)-1 for posteroanterior and lateral cineangiography, respectively. The dose data and conversion factors evaluated in the present study may be useful for estimating radiation exposure in infants during diagnostic cardiac catheterisation.

Estimation of Organ and Effective Doses for Neonate and Infant Diagnostic Cardiac Catheterizations.

OBJECTIVE: Radiation exposure to neonates and infants during cardiac catheterizations is an important issue. Smaller patient size and higher heart rate in these patients result in a greater need for magnification modes and higher frame rates, all of which contribute to a significant increase in radiation doses. The aims of our study were to evaluate organ and effective doses for neonates and infants during diagnostic cardiac catheterizations on the basis of in-phantom dosimetry and conversion factors from dose-area product (DAP) to the effective dose. MATERIALS AND METHODS: Organ doses for 0- and 1-year-old children during diagnostic cardiac catheterizations were measured by radiophotoluminescence glass dosimeters implanted in neonate and infant anthropomorphic phantoms. The effective doses were evaluated according to recommendations of the International Commission on Radiologic Protection (ICRP) publication 103. RESULTS: The mean effective doses evaluated according to ICRP 103 were 7.7 mSv (range, 0.1-18.4 mSv) for a neonate and 7.3 mSv (range, 1.9-18.6 mSv) for an infant. Conversion factors from DAP to the effective dose were 2.2 and 4.0 in posteroanterior and lateral cine angiography, respectively, for a neonate and 1.4 and 2.7 in posteroanterior and lateral cine angiography, respectively, for an infant. CONCLUSION: The dose data and conversion factors evaluated in this study could be useful for the estimation of radiation exposure in neonates and infants during diagnostic cardiac catheterization.

[Two cases of spontaneous cervical epidural hematoma mimicking cerebral infarction].

Spontaneous spinal epidural hematoma(SSEH)is a rare condition that typically presents with acute back pain and paraparesis or quadriparesis. However, hemiparesis is a rare initial symptom of SSEH. Here, we report two cases of SSEH presenting with hemiparesis, which were difficult to distinguish from cerebral stroke. In both cases, source images of MR angiography were useful for the diagnosis of SSEH. The first patient was an 84-year-old man who presented with monoparesis in the left lower extremity, without back pain. He was initially misdiagnosed with a cerebral stroke and treated inappropriately with antiplatelet agents. Five days after admission, the correct diagnosis of SSEH was made based on cervical magnetic resonance imaging. Source images of cervical MR angiography also revealed SSEH. He was managed conservatively because of his relatively mild symptoms and stable condition, and his symptoms improved by rehabilitation. The second patient was a 72-year-old woman who presented with right hemiparesis and back pain. Source images of cervical MR angiography revealed a right posterolateral epidural hematoma, and underwent emergency surgical decompression and hematoma removal. We emphasize that SSEH should be considered in the differential diagnosis for patients with acute hemiparesis, even though they do not complain of back pain, and that source images of neck MR angiography could be useful for quickly screening for SSEH.

Organ dose and effective dose estimation in paediatric chest radiographic examinations by using pin silicon photodiode dosemeters.

Organ and effective doses during paediatric chest radiographic examination were investigated for various tube voltages between 60 and 110 kV at a constant milliampere-second value and focus-to-film distance by using an in-phantom dose measuring system and a Monte Carlo (MC) simulation software (PCXMC), where the former was composed of 32 photodiode dosemeters embedded in various tissue and organ sites within a 6-y-old child anthropomorphic phantom. Lung doses obtained ranged from 0.010 to 0.066 mGy and effective doses from 0.004 to 0.025 mSv, where these doses varied by a factor of 6 with the change in the tube voltage. Effective doses obtained using the MC simulation software agreed with those obtained using the dose measuring system within 23 %, revealing the usefulness of PCXMC software for evaluating effective doses. The present study would provide helpful dose data for the selection of technical parameters in paediatric chest radiography in Japan.