Radiation dose to the patient and operator from a peripheral dual X-ray absorptiometry system

A comparative study of radiation doses between phantom and patients via CT angiography of the intra-/extra-cranial, pulmonary, and abdominal/pelvic arteries

This study aimed to evaluate effective dose and size-specific dose estimate (SSDE) of computed tomography angiography (CTA) examination using an anthropomorphic phantom. We included three CTA examination protocols to evaluate the intra- and extra-cranial arteries, pulmonary artery (CTPA), and abdominal vessels. Patient SSDEs were measured retrospectively to estimate patient dose, relative to the bodyweight of the patient and volume CT dose index (CTDI_vol). Our findings revealed that the highest dose was absorbed by the left lobe of the thyroid gland during intra-/extra-cranial CTA and CTPA, that is, 14.11 ± 0.24 mGy and 16.20 ± 3.95 mGy, respectively. However, the highest absorbed dose in abdominal/pelvic CTA was the gonads (8.98 ± 0.30 mGy), while other radiosensitive organs in intra- and extra-cranial CTA, CTPA, and abdominal/pelvic CTA did not demonstrate significant differences between organs/structures with p value 0.88, 0.11, and 0.54, respectively. The estimated effective dose in intra-/extra-cranial CTA was lower in patients (0.80 ± 0.60 mSv) than in the phantom (0.83 mSv), but it was the opposite for CTPA, with the effective dose being higher in patients (7.54 ± 3.09 mSv) than in the phantom (6.68 mSv). Similar to the effective dose, only CTPA SSDEs were significantly higher in men than in women (19.74 ± 4.79 mGy versus 7.9 mGy). Effective dose and SSDE are clinically relevant parameters that can help estimate a more accurate patient dose based on a patient's size.

The DXL Calscan heel densitometer: evaluation and diagnostic thresholds

The DXL Calscan (Demetech AB) is a new dual energy X-ray absorptiometry device for determining heel bone mineral density (BMD). The system is based on the standard technique of dual energy X-ray absorptiometry (DXA), using a fan beam configuration, but introduces an additional laser measurement of heel thickness intended to improve accuracy. We have examined the utility, in vitro and in vivo performance of the DXL Calscan and established triage thresholds based on the UK's National Osteoporosis Society guidelines on peripheral densitometry. The Calscan proved convenient, easy to use and was stable over time and within a range of operating temperatures. Short-term in vitro precision as %CV, with phantom repositioning, was 0.75% and long term precision 0.73%. Precision in vivo, determined from duplicate right heel scans of 67 subjects, was 1.19%. Effective radiation dose to the patient was <0.1 microSv per scan. 140 white females (70 osteoporotic and 70 non-osteoporotic), aged 55-70 years underwent scans of both heels. Subjects were defined as osteoporotic or non-osteoporotic on the basis of axial DXA (spine L2-L4 and total hip). Triage thresholds for reassurance-referral or referral-treatment were 0.391 g cm(-2) and 0.306 g cm(-2) for non-dominant and 0.395 g cm(-2), 0.294 g cm(-2) for dominant heel, respectively. The non-dominant heel proved slightly superior to the dominant for triage purposes. Of the seven non-osteoporotic subjects misclassified as osteoporotic by Calscan of either heel, six had severe axial osteopenia. If operated by trained personnel and used in appropriate populations exhibiting risk factors, the Calscan is well suited for use in the management of post-menopausal osteoporosis.

Ethnic differences in bone mineral density between inuit and Caucasians in north Greenland are caused by differences in body size

Data on bone mineral density (BMD) in living Inuit are limited and BMD measurements in Arctic Inuit using Dualenergy X-ray Absorptiometry (DXA) are lacking. Ethnicity may be important for bone mass. The aim of this study was to validate DXA in rural Arctic Greenland, to measure BMD in Greenland Inuit and Caucasians, and to estimate the importance of ethnicity for BMD. We measured the BMD in 80 healthy subjects living in Ilulissat and Saqqaq in North Greenland twice in both distal forearms and in both heels using peripheral DXA (pDXA). Participants were stratified by origin (Inuit[settlement])/Caucasians, n = 33 [19]/28), gender (men/women, n = 37/43), and age (30-39/40-49, n = 32/48). Caucasians were bigger than Inuit (men/women, height p < 0.001/p < 0.001; weight p = 0.01/ p = 0.026), but had similar BMI (p = 0.42/0.70). Triplicate pDXA measurements showed individual CV% = 0.16-1.79%; overall CV% = 1.1% (forearm)/1.0% (heel). Data followed the normal distribution (p = 0.65-0.99) with identical variances between Inuit and Caucasians (p = 0.12-0.63). Mean BMD in right forearm/left forearm/right heel/left heel was: Inuit men 0.570/0.568/0.549/0.536 g/cm2; Inuit women 0.484/0.474/0.473/0.464 g/cm2; Caucasian men 0.580/0.570/0.646/0.638 g/cm2; Caucasian women 0.495/0.496/0.552/0.553 g/cm2. An ethnic difference in heel BMD (p < 0.001) disappeared when adjusted for weight (p = 0.30). No difference was found in forearm BMD. In conclusion, pDXA is feasible and reliable in rural Greenland. Ethnic differences in BMD are small and may reflect differences in body size.

Forearm single X-ray absorptiometry in the identification of postmenopausal women with osteoporosis at the hip and spine: a correlation study

The International Society for Clinical Densitometry (ISCD) has stated that forearm bone mineral density (BMD) testing combined with a thorough clinical evaluation may be an option for the diagnosis of osteoporosis when central bone density (CBD) testing is not available. This study assessed the performance of two different forearm sites in identifying subjects with spinal and femoral osteoporosis, and defined the 90% sensitivity point for the DTX-100 bone densitometer in the detection of central osteoporosis. Four hundred and two postmenopausal Bulgarian women between the ages of 50 and 81 yr (mean age 60.24 +/- 10.48 yr) participated in this study. Forearm BMD (distal and ultradistal forearm) was measured with a DTX-100 device (Osteometer Meditech, USA) and central BMD (lumbar spine and proximal femur) with a Hologic QDR 4500 A device. Linear T-score correlations among sites, sensitivity and specificity of the forearm site were analyzed. T-score correlations between the forearm and the central sites ranged from 0.32 to 0.69 (p < or = 0.05 for all correlations in age group 50-59). The forearm site sensitivity increased slightly with advancing age, but specificity decreased. When the distal forearm BMD cut point (0.340 g/cm2) was set to achieve 90% sensitivity to identify total hip osteoporosis, specificity was 40%; when the distal forearm BMD cut point (0.410 g/cm2) was set to achieve 90% sensitivity to identify spinal osteoporosis, specificity was 55.4%; when ultradistal forearm BMD cut points (0.280 and 0.320 g/cm2) were set to achieve 90% sensitivity to identify total hip and spinal osteoporosis, specificity was 40.8 and 59.2%, respectively. Forearm bone density measures may be useful to selectively screen for patients with central osteoporosis.

Bone densitometry and the diagnosis of osteoporosis

Over the past decade, bone density scanning has come to be seen as an essential part of the evaluation of patients at risk of osteoporosis. Although dual x-ray absorptiometry (DXA) is the technique most associated with the recent growth in bone densitometry, several innovative devices for performing measurements at sites in the peripheral skeleton are also available. This article examines the question of whether there is any one method or measurement site that performs better than all the others at identifying patients at risk of fracture. Given that it is essential to make greater use of the small, low-cost peripheral devices if the many millions of women most at risk are to be identified and treated, what approaches to the interpretation of bone density scans can be adopted to ensure the greatest degree of consistency among different methods? Finally, does it matter if the imperfect correlation among different types of measurement results in different patients being selected for treatment on the basis of different techniques?