Semiconductor Radiation Probes for Nuclear Medicine and Radiobiology the State of the Art

Detection of periodontal disease activity with a scintillation camera

The goal of this study was to assess the ability of a scintillation camera method to detect areas of active bone loss due to periodontitis. Technetium 99m methylene diphosphonate was used as the bone-seeking radiopharmaceutical. Bone-seeking radiopharmaceutical uptake (BSRU) was imaged and quantified in alveolar bone regions of interest with a scintillation camera and a computer. Analysis of the sequential radiographs over six months constituted the basis for determination of sites of active disease. The study was composed of two parts. First, 18 subjects, nine with adult periodontitis and nine controls, were enrolled in a cross-sectional study to determine whether the quantitative scintillation amera methodology detected differences in BSRU in periodontitis vs. periodontally healthy patients. Second, the nine patients with periodontitis were studied longitudinally in order to determine whether the BSRU examination was indicative of bone loss subsequently measured radiographically. In the cross-sectional study, the mean uptake ratio for the periodontitis group was significantly higher than that for the control group (1.63 +/- 0.06 and 1.42 +/- 0.04, respectively, p less than 0.01, t test). From the longitudinal study, the mean patient scintillation image uptake ratios were highly correlated with the mean bone loss determined from serial radiographs (p less than 0.01). The accuracy, sensitivity, and specificity of the quantitative gamma camera method for detecting site(s) of active bone loss within the region of interest were assessed relative to the longitudinal radiographic data. The accuracy, sensitivity, and specificity were 85%, 90%, and 79%, respectively. Alveolar bone scintigraphy with a gamma camera and computer may provide a simple and valid technique for the immediate indication of areas of periodontal disease activity.

Studies on focal alveolar bone healing with technetium (Tc)-99m labeled methylene diphosphonate and gold-collimated cadmium telluride probe

The benefit of using a collimator for a miniaturized cadmium telluride probe was evaluated by monitoring the bone-healing processes for 13 weeks after the induction of small iatrogenic alveolar bone lesions in one side of the mandible in beagles. Technetium (Tc)-99m labeled methylene diphosphonate (200 to 300 MBq, 5.1 to 8.1 mCi, in a solution of 0.5 to 1 ml, intravenously) was used as a bone-seeking radiopharmaceutical. The radioactivity over the bone lesion (L) and the contralateral normal site (C) in the mandible were measured between 1.5 and 2 hours after injection of the tracer, and the activity ratio L/C served as an index of relative bone uptake. A study of six dogs revealed that the healing response to a hemispheric bone defect of 2 mm diameter in the cortical bone could not be detected by an uncollimated probe, and in a repeated study in two dogs the use of a gold collimator (5 mm in diameter, 5 mm in length) did not increase the L/C ratio significantly. A second study in six dogs with 5 mm lesions showed that although systematic trends in the time courses of the L/C ratio obtained both with and without the collimator could be demonstrated, the L/C ratio of collimated versus uncollimated measurements was significantly (p less than 0.005) increased. In three of the latter six dogs, abscesses developed after 9 weeks, leading to a second increase (p less than 0.05) of the L/C ratio with collimation compared with the noninflammation group; without collimation no significant (p greater than 0.15) difference between the two groups could be demonstrated.(ABSTRACT TRUNCATED AT 250 WORDS)

Nuclear medicine techniques for the detection of active alveolar bone loss

The use of bone-seeking radiopharmaceutical uptake (BSRU) as an indicator of periodontal disease activity was assessed in untreated beagles with naturally occurring periodontal disease, and in beagles treated with the non-steroidal anti-inflammatory drug, flurbiprofen. In untreated beagles, a single uptake measurement was indicative of the rate of bone loss subsequently determined by sequential radiographs. Beagles treated with flurbiprofen demonstrated a significant decrease in rate of bone loss and a corresponding decrease in BSRU. Transfer of this technology to untreated human subjects with moderate to severe periodontal disease also showed a positive correlation between a single measurement of BSRU and the rate of bone loss determined from sequential radiographs. Analysis of these data shows that a single BSRU examination may be indicative of periodontal disease activity.

Predicting alveolar bone loss in beagles using bone-seeking radiopharmaceutical uptake

Measurements of bone-seeking radiopharmaceutical uptake obtained at the beginning of this two-year study of beagles with periodontal disease were correlated with the amount of bone loss which occurred during the study. Uptake correlated with bone loss (r = 85), which suggests that uptake may be an indicator of future bone loss.

Semiconductor probe measurements in beagle pups during deciduous tooth development

Bone-seeking radiopharmaceuticals were used together with clinical and radiographic procedures to study tooth development in dogs. Similarities in the pattern and time course of radiopharmaceutical uptake in jaw areas studied suggest that changes in alveolar bone metabolism are not closely related to eruption times of individual teeth.

A radiotelemetry pill for the measurement of ionising radiation using a mercuric iodide detector

A small radiation measuring pill is briefly described which utilises the principles of radiotelemetry and the properties of a room temperature semiconductor radiation detector such as mercuric iodide. By transmitting a radio signal to a remote receiver the pill could be an effective tool in localising bleeding sites along the gastrointestinal tract and also possibly in the diagnosis of gastrointestinal carcinoma. Other uses of the radiopill are suggested. The size of the pill is 27 mm x 10 mm diameter and consists of a mercuric iodide crystal, an amplifier, a frequency modulated transmitter and one battery. The radiotransmitter operates at about 106 MHz and has a range of about 10m, and the sensitivity of the pill has been found for 99Tcm, 131I and 32P.

Semiconductor probe measurements in beagle dogs with periodontal disease

A miniaturized semiconductor probe was used to measure alveolar bone uptake of a bone-seeking radiopharmaceutical in dogs with destructive periodontal disease. Radiopharmaceutical uptake in localized, advanced disease was greater than in incipient disease and was generalized, with increased uptake occurring in radiographically normal areas and in areas with bone loss.