Samarium-153 EDTMP for metastatic bone pain palliation: the impact of europium impurities.

PURPOSE: To evaluate the impact on the radiation protection policies of the radiocontaminants in Samarium-153 ethylenediamine tetramethylene phosphonate ((153)Sm-EDTMP). METHODS: The internal contamination of patients treated with (153)Sm-EDMTP for palliation of painful disseminated multiple bone metastases due to long-lived impurities was assessed by direct measurements. These measurements were coupled with dose-rate measurements close to their bodies and spectroscopic analysis of the residual activity in post-treatment radiopharmaceutical vials. RESULTS: Whole-body counting carried out in six patients showed a 30-81-kBq europium -152 plus europium-154 contamination. The 0.85 mean (152)Eu- to -(154)Eu activity ratio obtained by direct counting was similar to that assessed by analysis of post-treatment residual activities in twelve radiopharmaceutical vials following radiopharmaceutical injection. CONCLUSIONS: The long-lived radiocontaminants in the patient's bodies and the treatment wastes require modifications of the applicable radiation protection policies.

Endovascular abdominal aortic aneurysm repair: methods of radiological risk reduction.

AIM: The management of abdominal aortic aneurysm with endovascular repair (EVAR) requires extended exposure to ionizing radiation, before, during and after the intervention. The aim of this study was to quantify the radiological risks to patients and operating team, and to develop strategies to assess and reduce them. METHODS: EVAR was carried out in 97 patients using either a low-power mobile or a high-power stationary fluoroscopic unit. Empirically determined relationships between the indicated dose area product (DAP) and peak skin dose, obtained by direct in vivo dosimetry in a subgroup of patients, were used to predict the peak skin dose. Individual worker monitoring was used to assess personnel radiological burden. RESULTS: The probability for radiation induced biological effects due to the repair itself and the preoperative and life-long surveillance, as carried out, was about 2.4 10-3. The peak skin dose of repairs was linearly correlated with the DAP and did not exceed 1.2 Gy. The collective effective dose of the staff that carried out repairs using the mobile unit was 5.5 and 8 µSv per repair using an angiographic and a surgical table, respectively. The use of the high-power fluoroscopic unit resulted in a many fold higher radiation burden to both patient and personnel. CONCLUSION: The optimum strategy, including equipment-related factors, procedure-conduct factors and follow-up procedures, has to be studied, justified and optimized in each medical facility.

A high-sensitivity multidetector whole-body counter.

A prototype multidetector shadow-shield whole-body counter is presented to be used as a monitor of internal contamination and as a tool in clinical research. The counter is equipped with 16 NaI(Tl) detectors located in the central region of a shielded tunnel surrounding the subject to be measured. The accuracy of the counting efficacy predictions was tested in a group of adults with various body shapes and sizes using X-ray absorptiometry. The precision of the total body potassium measurements allows the use of the counter in clinical follow-up studies.

Age at menarche, age at menopause and duration of fertility as risk factors for osteoporosis.

OBJECTIVE: To investigate the relationship of osteopenia and osteoporosis in apparently healthy postmenopausal patients with age at menarche, age at menopause and duration of fertility. PATIENTS AND METHODS: One hundred and twenty-four apparently healthy Greek postmenopausal women underwent spinal and hip X-ray absorptiometry scans. Among them, 47 were classified as normal (control group), 52 as osteopenic, and 25 as having osteoporosis. These groups were compared according to their age at menarche (three subgroups of 10-12, 13 and 14-16 years old), at menopause (three subgroups of 40-45, 46-50 and > or = 51 years old) and duration of fertility (four subgroups of < or = 30, 31-35, 36-40 and 41-45 years). RESULTS: The groups were not found to differ statistically according to age and age at menarche. However, decreased bone mineral density was found in patients with duration of fertility not exceeding 30 years (p = 0.034) and age at menopause less than 45 years (p = 0.034). No association was found between bone mineral density in Greek postmenopausal women and either number of live births or lactation. CONCLUSIONS: In postmenopausal females, the cumulative exposure to endogenous estrogens, measured as years of menstruation, seems to be a significant protective factor against the development of postmenopausal osteoporosis. Age at menopause between 40 and 45 years, but not age at menarche, correlated with low bone mineral density in postmenopausal females.

Thermoluminescence dosimetry for quality assurance in radiation therapy.

A methodology based on thermoluminescence dosimetry was developed to check the output of teletherapy units and the given doses. It was applied in a hospital as a part of an extemal quality audit programme. Over a 7 year period the mean ratios of the output doses measured by TLDs calibrated free-in-air to the doses measured at the hospital in a 6 MV X ray and in a 60Co unit were 1.000 +/- 0.024 (n = 86) and 0.997 +/- 0.027 (n=61), respectively. TLDs in capsules were attached to the patient's body or to a phantom to assess entrance, exit and midline doses and transmission. Factors were determined experimentally to relate the doses measured with TLDs in capsules and inside the body. The accuracy in given doses with pelvic and tangential breast fields and assessed via 752 in vivo measurements, was considered to be adequately good, taking into account the limitations of the equipment available in the hospital.

Boron neutron capture therapy of a murine mammary carcinoma using a lipophilic carboranyltetraphenylporphyrin.

The first control of a malignant tumor in vivo by porphyrin- mediated boron neutron capture therapy (BNCT) is described. In mice bearing implanted EMT-6 mammary carcinomas, boron uptake using a single injection of either p-boronophenylalanine (BPA) or mercaptoundecahydrododecaborane (BSH) was compared with either a single injection or multiple injections of the carboranylporphyrin CuTCPH. The BSH and BPA doses used were comparable to the highest doses of these compounds previously administered in a single injection to rodents. For BNCT, boron concentrations averaged 85 microg (10)B/g in the tumor and 4 microg (10)B/g in blood 2 days after the last of six injections (over 32 h) that delivered a total of 190 microg CuTCPH/g body weight. During a single 15, 20, 25 or 30 MW-min exposure to the thermalized neutron beam of the Brookhaven Medical Research Reactor, a tumor received average absorbed doses of approximately 39, 52, 66 or 79 Gy, respectively. A long-term (>200 days) tumor control rate of 71% was achieved at a dose of 66 Gy with minimal damage to the leg. Equivalent long-term tumor control by a single exposure to 42 Gy X rays was achieved, but with greater damage to the irradiated leg.

Electron density of tissues and breast cancer radiotherapy: a quantitative CT study.

PURPOSE: To obtain more accurate data on the electron density of tissues to be used in the treatment planning of breast cancer patients. METHODS AND MATERIALS: Single kVp quantitative computed tomography was applied in 70 women, 20 to 77 years old, to study the electron density of the breast, the thoracic wall close and parallel to the breast, and the lung parenchyma. RESULTS: The electron density of the entire breast decreases with increasing age in premenopausal women and remains practically constant in postmenopausal women (8% less than that of water). No difference was found in the electron densities of the right and left breast. The electron density of the lung parenchyma in proximity to the breast is lower than the density in the entire lung parenchyma. CONCLUSIONS: Whenever no accurate data is available on individual patients, the electron density values to be used in treatment planning for breast and thoracic wall have to take into account both age and menstrual status. The regional differences in electron density of the lung also have to be considered.

Software upgrading in a CT scanner. Influence on quantitative CT.

PURPOSE: In an attempt to improve field uniformity and CT number stability, the software in a CT scanner was replaced with a new version. The purpose of the present study was to investigate the influence of the software upgrading on density measurements. MATERIAL AND METHODS: The upgrading influence was investigated by means of a torso phantom (European spinal). The phantom simulates a torso which contains 3 vertebrae of different densities. RESULTS: Despite the use of a reference standard under the phantom, the software change resulted in: a) improved short-term precision; b) increased density values at 80 and 100 kVp, decreased at 130 kVp; and c) increased influence of the kVp on the values. CONCLUSION: The results of the present study suggest that conversion factors have to be used in density values for reference populations as well as in the values of patients undergoing follow-up studies.

Amount and composition of bone minerals in chronic liver disease.

Alterations in bone mineral are a common complication of chronic liver disease. The aim of the current study was to assess bone mineral status in patients with chronic liver disease not treated with corticosteroids and to investigate any possible correlation with the histological stage of liver disease. Bone mineral status in 27 patient with chronic active hepatitis, and 17 with active cirrhosis was compared to that of matched controls. Partial body neutron activation analysis was applied for measuring hand bone phosphorus, single-photon absorptiometry for measuring forearm bone mineral content, and dual-energy x-ray absorptiometry for measuring spinal bone mineral density. These noninvasive measurements were supplemented with data obtained by high resolution radiography and biochemistry. Decreased metacarpal cortical thickness was found in five patients, all in the cirrhotic group. In addition, both mean intact parathyroid hormone and 25-hydroxyvitamin D levels were reduced in this group of patients. The mean values of the quantities assessed by the in vivo techniques in patients in the early stages of the hepatic disease did not differ statistically from those of matched normal controls. On the contrary, these quantities were reduced by 9% in the patients at the late stages relative to controls. In conclusion, only the late stages of liver disease are associated with an increased risk of fractures.

Quantitative computed tomography for spinal bone mineral measurements in chronic renal failure.

The aim of this study was to assess non-invasively the status of spinal trabecular bone in patients with chronic renal failure and the influence of the disease stage. Single energy quantitative computed tomography (CT) was used in 89 patients with chronic renal failure to measure spinal trabecular bone equivalent density. 23 patients were independent of dialysis and 66 were receiving long-term haemodialysis. Spinal trabecular bone density of the patients was compared with locally determined normal ranges. Although trabecular bone mineral density (BMD) was lower (9% on average) in the patients who were not dependent on dialysis compared with the predicted mean normal values (BMDp) for age- and sex-matched normal subjects, the difference was not statistically significant. A statistically significant reduction was found in patients on dialysis (BMD/BMDp 0.75 +/- 0.16, Z-score -1.3). Osteosclerosis was found in 11 patients and they were excluded from the study. Longitudinal measurements in 42 patients on dialysis without osteosclerosis showed a 2.9% mean reduction in BMD/BMDp over a period of 8 months. All but one of the 16 haemodialysis patients with osteopenic spinal fractures had trabecular BMD values lower than the fracture threshold determined by our technique. In conclusion, end-stage chronic renal failure was associated with reduction in the spinal trabecular bone density.

Elemental composition of bone minerals in women with breast cancer treated with adjuvant tamoxifen.

Oestrogen levels play a major role in conditioning the rates of bone changes in women. Tamoxifen is a synthetic oestrogen antagonist commonly used as an adjuvant therapy for breast cancer. The goal of the present study was to study the amount and the elemental composition of bone minerals in the appedicular skeleton of women with breast cancer treated with adjuvant tamoxifen, as well as to investigate the possibility of increased risk for osteoporosis. Forty-two patients, aged 41-65 years, without skeletal metastases were studied. The mean duration of tamoxifen administration on a daily dose of 20 mg was 21 months (range 1-59 months). It was found that neither the amount of phosphorus in hands (HBP) nor forearm bone mineral content (BMC) differ statistically from those of age-matched healthy subjects. This was confirmed by reassessing bone mineral status after 30 months in 17 postmenopausal patients treated with tamoxifen for a mean time of 52 months. In conclusion, our data support that long-term tamoxifen treatment has no adverse or protective effect on the amount and elemental composition of the appedicular skeleton.

Bone mineral status after renal transplantation. Assessment by noninvasive techniques.

RATIONALE AND OBJECTIVES: Bone mineral status in recipients of renal grafts is related to preexisting renal osteodystrophy and immunosuppressive treatment. The authors assessed bone mineral status after renal transplantation. METHODS: Bone mineral status of 20 male graft recipients was evaluated using the following noninvasive techniques: 1) neutron activation analysis, to measure hand bone phosphorus (HBP); 2) single photon absorptiometry, to measure forearm bone mineral content (BMC); and 3) single energy spectrum quantitative computed tomography, to measure spinal trabecular bone equivalent density (TBED). RESULTS: The mean (+/- SD, P) HBP, BMC, and TBED were found to be respectively, 4.8% (+/- 8.3%, P = .02), 6.6% (+/- 14.6%, P = .07) and 52% (+/- 8.5%, P < .001) lower than that measured in matched normal controls. Renal graft recipients demonstrated mean HBP and BMC decrements that were similar to those observed in matched patients on extrarenal dialysis, although the decrement in TBED was significantly greater in the graft recipients (P < .001). Repeated measurements performed during a 3-year period showed no statistically significant changes. CONCLUSIONS: Renal transplantation was associated with minor degree of osteopenia in the primarily cortical bone tissue. We speculate that the remarkably low TBED values in graft recipients does not reflect a mean 52% decrement of spinal bone minerals, but rather may be attributed in part to the deposition of adipose tissue in the spine as a result of corticosteroid treatment.

Sequential measurements of bone lead content by L X-ray fluorescence in CaNa2EDTA-treated lead-toxic children.

With the development of L X-ray fluorescence (LXRF) to measure cortical bone lead directly, safely, rapidly, and noninvasively, the present study was undertaken to a) evaluate LXRF as a possible replacement for the CaNa2EDTA test; b) quantify lead in tibial cortical bones of mildly to moderately lead-toxic children before treatment; and c) quantify lead in tibial cortical bones of lead-toxic children sequentially following one to two courses of chelation therapy. The clinical research design was based upon a longitudinal assessment of 59 untreated lead-toxic children. At enrollment, if the blood lead (PbB) was 25 to 55 micrograms/dL and the erythrocyte protoporphyrin (EP) concentration was greater than or equal to 35 micrograms/dL, LXRF measurement of tibial bone lead was carried out. One day later, each child underwent a CaNa2EDTA provocative test. If this test was positive, lead-toxic children were admitted to the hospital for 5 days of CaNa2EDTA therapy. These tests were repeated 6 weeks and 6 months after enrollment. Abatement of lead paint hazards was achieved in most apartments by the time of initial hospital discharge. The LXRF instrument consists of a low energy X-ray generator with a silver anode, a lithium-doped silicon detector, a polarizer of incident photons, and a multichannel X-ray analyzer. Partially polarized photons are directed at the subcutaneous, medial mid-tibial cortical bone. The LXRF spectrum, measured 90 degrees from the incident beam, reveals a peak in the 10.5 KeV region, which represents the lead L alpha line.(ABSTRACT TRUNCATED AT 250 WORDS)

Quantitative computed tomography for bone mineral measurement: technical aspects, dosimetry, normal data and clinical applications.

A single KVp quantitative CT (QCT) technique was used for measuring the spinal trabecular bone density. The trabecular bone equivalent density (TBED) was expressed as the density of a K2HPO4 solution that exhibits a linear attenuation coefficient identical to that of trabecular bone. A field non-uniformity correcting factor was obtained from experiments on phantoms. The effective equivalent dose of the whole examination (four sections and a scout view) is 370 muSv. The in vivo short-term precision (reproducibility coefficient of variation) ranges from 1.4% to 4.1% depending on the TBED values of the normal subjects. The TBED was measured in 206 normal Greeks aged 30-69 years. Average TBED decreased with increasing age for both sexes. Analysis considering separately each vertebra showed a tendency to a caudal spinal TBED reduction. No correlation was found between the TBED values and the body habitus, milk consumption, smoking habits in men, and number of full-term pregnancies. A significant difference (p less than 0.01) was found between the TBED values of the normals and those of 50 women suffering from post-menopausal osteoporosis, 37 alcoholic men, and 12 gastrectomized men (Billroth II). Quantitative CT has been established as a method of measuring TBED in health and disease, and the results from this study confirm these applications.

Sequential measurements of bone lead content by L X-ray fluorescence in CaNa2EDTA-treated lead-toxic children.

With the development of L X-ray fluorescence (LXRF) to measure cortical bone lead directly, safely, rapidly, and noninvasively, the present study was undertaken to a) evaluate LXRF as a possible replacement for the CaNa2EDTA test; b) quantify lead in tibial cortical bones of mildly to moderately lead-toxic children before treatment; and c) quantify lead in tibial cortical bones of lead-toxic children sequentially following one to two courses of chelation therapy. The clinical research design was based upon a longitudinal assessment of 59 untreated lead-toxic children. At enrollment, if the blood lead (PbB) was 25 to 55 micrograms/dL and the erythrocyte protoporphyrin (EP) concentration was greater than or equal to 35 micrograms/dL, LXRF measurement of tibial bone lead was carried out. One day later, each child underwent a CaNa2EDTA provocative test. If this test was positive, lead-toxic children were admitted to the hospital for 5 days of CaNa2EDTA therapy. These tests were repeated 6 weeks and 6 months after enrollment. Abatement of lead paint hazards was achieved in most apartments by the time of initial hospital discharge. The LXRF instrument consists of a low energy X-ray generator with a silver anode, a lithium-doped silicon detector, a polarizer of incident photons, and a multichannel X-ray analyzer. Partially polarized photons are directed at the subcutaneous, medial mid-tibial cortical bone. The LXRF spectrum, measured 90 degrees from the incident beam, reveals a peak in the 10.5 KeV region, which represents the lead L alpha line.(ABSTRACT TRUNCATED AT 250 WORDS)

Boron neutron capture therapy of intracerebral rat gliosarcomas.

The efficacy of boron neutron capture therapy (BNCT) for the treatment of intracerebrally implanted rat gliosarcomas was tested. Preferential accumulation of 10B in tumors was achieved by continuous infusion of the sulfhydryl borane dimer, Na4(10)B24H22S2, at a rate of 45-50 micrograms of 10B per g of body weight per day from day 11 to day 14 after tumor initiation (day 0). This infusion schedule resulted in average blood 10B concentrations of 35 micrograms/ml in a group of 12 gliosarcoma-bearing rats and 45 micrograms/ml in a group of 10 similar gliosarcoma-bearing rats treated by BNCT. Estimated tumor 10B levels in these two groups were 26 and 34 micrograms/g, respectively. On day 14, boron-treated and non-boron-treated rats were exposed to 5.0 or 7.5 MW.min of radiation from the Brookhaven Medical Research Reactor that yielded thermal neutron fluences of approximately 2.0 x 10(12) or approximately 3.0 x 10(12) n/cm2, respectively, in the tumors. Untreated rats had a median postinitiation survival time of 21 days. Reactor radiation alone increased median postinitiation survival time to 26 (5.0 MW.min) or 28 (7.5 MW.min) days. The 12 rats that received 5 MW.min of BNCT had a median postinitiation survival time of 60 days. Two of these animals survived greater than 15 months. In the 7.5 MW.min group, the median survival time is not calculable since 6 of the 10 animals remain alive greater than 10 months after BNCT. The estimated radiation doses to tumors in the two BNCT groups were 14.2 and 25.6 Gy equivalents, respectively. Similar gliosarcoma-bearing rats treated with 15.0 or 22.5 Gy of 250-kilovolt peak x-rays had median survival times of only 26 or 31 days, respectively, after tumor initiation.

In vivo measurement of cortical bone lead using polarized x rays.

An x-ray fluorescence system which utilizes polarized radiation to measure lead in vivo in human subjects is described. The minimum detection limit is approximately 6.4 ppm wet weight lead in the cortex of the tibia with 4 mm of overlying soft tissue. This appears to be adequate for assessing lead stores in lead-toxic preschool children. The measurement requires 16.5 min and is associated with an effective equivalent whole body dose to the subject of 2.5 muSv. The system, its calibration and its validation are described herein.