Correction of the effects of source, source strength, and soft-tissue thickness on spine dual-photon absorptiometry measurements.

Dual photon absorptiometry measurements of the spine are subject to drift associated with source, source strength, and truncal thickness. This study was conducted to determine the extent to which this drift in bone mineral density (BMD) measurements can be improved by analysis of scans with a new software version, 08C, and by applying external standard or phantom corrections to scans analyzed with the older version, 08B. A phantom, consisting of human lumbar vertebrae embedded in acrylic, and five clear acrylic plates to simulate a soft-tissue thickness range of 15.2-27.9 cm, was measured on a Lunar Radiation Corp DP3 scanner over the life of a 153-gadolinium (Gd) source and scans analyzed with software versions 08B and 08C. Phantom BMD was lower with 08C at both high [0.012 +/- 0.002 (SEM) g/cm2, P less than 0.001] and low (0.027 +/- 0.003 g/cm2, P less than 0.001) count rates than with 08B. Phantom BMD of scans analyzed with 08B increased with increasing source age and the source strength-related increment increased significantly as acrylic thickness increased (P = 0.014). When the same scans were analyzed with 08C, the thickness-related effect was corrected whereas a small (0.011 g/cm2/year) source-strength effect persisted. The effects of source strength and truncal thickness on BMD were also evaluated in 40 humans scanned at two detector collimations to vary count rate. With 08B, mean BMD was 1% greater when measured with 8 than with 13 mm collimation (mean difference 0.011 +/- 0.003 g/cm2, P = 0.001), whereas the version 08C, mean BMD was the same at the two collimations.(ABSTRACT TRUNCATED AT 250 WORDS)

Precision of dual-photon absorptiometry.

Precision of dual-photon absorptiometry (DPA) measurements was determined in a lumbar spine phantom and in humans. Approximately half of the measurements were made before and half after a 153gadolinium source change. The phantom was measured with different amounts of acrylic, which simulates human soft tissue, in order to evaluate the influence of body thickness on bone mineral density (BMD). Results of scans analyzed with two software versions from Lunar Radiation Corp., the widely used 08B and a prototype 08C, are compared. DPA with a cold source significantly overestimated BMD in the phantom in the presence of large amounts (more than 25 cm) of soft tissue equivalent with version 08B but not with the newer version 08C. Similarly, in nine subjects, there was a significant decrease in spine BMD after a source change when scans were analyzed with version 08B (mean difference 0.026 g/cm2, P = 0.002) but not with 08C (0.01 g/cm2, P = 0.234). No systematic effect of source change on femoral BMD measurements was observed. The SD of the mean difference of two measurements of the nine subjects was 0.019 g/cm2 (1.6% of the mean value) for the spine with software version 08B and 0.024 g/cm2 (2.0%) with version 08C, 0.03 g/cm2 (3.3%) for the femur neck, 0.03 g/cm2 (4.0%) for the greater trochanter, and 0.04 g/cm2 (4.9%) for Ward's triangle region of the proximal femur. The spine phantom was scanned on two other commercial bone densitometers in order to assess inter-instrument variation.(ABSTRACT TRUNCATED AT 250 WORDS)

Radiation-induced cranial nerve palsy.

Twenty-five patients with 35 cranial nerve palsies were seen at the Fondation Curie during follow-up after radical radiotherapy for head and neck tumors. The twelfth nerve was involved in 19 cases, the tenth in nine, and the eleventh in five; the fifth and second nerves were involved once each and in the same patient. The twelfth nerve was involved alone in 16 patients and the tenth nerve alone in three, with multiple nerves involved in the remaining six patients. The palsy was noted from 12 to 145 months after diagnosis of the tumor. The latency period could be correlated with dose so that the least square fit equation representing NSD vs delay in NSD = 2598 - Delay (in months) X 4.6, with a correlation coefficient of -0.58. The distinction between tumor recurrence and radiation-induced nerve palsy is critical. It can often be inferred from the latency period but must be confirmed by observation over a period of time.

The use of intrauterine and intravaginal radium in the treatment of carcinoma of the bladder in women.

Eight women with advanced stage or high grade carcinoma of the bladder were treated in part with intrauterine and/or intravaginal radium. Local control was achieved in 7 cases. This is an effective form of treatment which should be considered for all women with bladder carcinoma.

The induction of non-specific autoimmune phenomena by radiotherapy.

Induction of autoimmune phenomena by radiotherapy was evaluated with fluorescent antinuclear antibodies (FANA), latex fixation, and C'3 complement. 27 random serum samples obtained prior to radiotherapy revealed only a low C'3 in a patient with Hodgkin's disease and Sjögren's syndrome. 33 random serum samples obtained after radiotherapy revealed 7 positive values (5 FANA, 1 latex fixation, and 1 C'3). The increase in positive values was statistically significant.