A survey of 14 computed tomography scanners in Greece and 32 scanners in Italy. Examination frequencies, dose reference values, effective doses and doses to organs.

A survey of examination frequencies, dose reference values, effective doses and doses to organs involving 14 scanners from Greece and 32 scanners from Italy was carried out for the years 1999 and 2000. Examination frequencies per scanner and per year were found to be 3590 for Greece and 4520 for Italy. For the types of examinations considered, CDTI(W) and DLP measurements were taken. Also scan lengths used for the same types of examinations were monitored. For the same types of examinations effective doses were calculated by two methods, and it was found that their mean values ranged from 13.1 mSv for thoracic spine to 1.6 mSv for the brain examinations. From the data of the 14 Greek laboratories, doses to organs were calculated and it was found that the thyroid receives 50.2 +/- 19.8 mGy during a cervical spine examination while the gonads receive 17.8 +/- 6.9 mGy during a routine pelvis examination.

Personnel doses in haemodynamic units in Greece.

Personnel of haemodynamic and interventional radiology units receive continuously increasing radiation doses due to extended fluoroscopy. Moreover, there is not a parallel increase in the number of cardiology specialists involved. Doses received by 15 cardiologists and 5 nurses, in 5 Athenian hospitals were measured using thermoluminescence dosemeters (TLD) and film badges. The workload and examination protocol of each cardiologist, the technical characteristics of the X ray unit, as well as availability and use of protective equipment were recorded. Results show that doses measured by TLD and film badges differ due mainly to the irregular wear of the latter. Although X ray units performed comparably with each other, dose per procedure received by each cardiologist varied widely, due to differences in examination protocol and beam collimation used. In all cases, nurses' dose was approximately one fourth of cardiologists' dose. In half of the cases assessed, the protective equipment available was not in full use. Estimation of dose per procedure, taking into account personnel's workload assesses annual personnel doses. Evaluation of risk level and check of compliance with regulatory dose limits should be part of continuing radiation protection education.

Patient dose, image quality and radiographic techniques for common X ray examinations in two Greek hospitals and comparison with European guidelines.

The radiographic technique factors and the quality of each radiographic image for three common examinations (chest PA, pelvis AP and lumbar spine LAT) were compared with the European criteria and entrance surface dose (ESD) was measured for each radiograph in two Greek hospitals. The measurements were carried out using calibrated LiF thermoluminescence dosemeters. The patients were selected so that their weight was close to 70 +/- 10 kg and their height to 170 +/- 10 cm. Effective dose values were calculated using a PC-based Monte Carlo program. All four X ray rooms in the survey achieved mean doses well below the European reference doses. However the mean doses in the X ray rooms differed by a factor of about 3.

Examination frequencies and patient doses from computed tomography examinations in the area of Athens, Greece.

A survey was conducted in the Athens region between the years 1996-1997, in which 33 CT scanner facilities from the 67 operating in this area participated. Examination frequencies from the 33 scanners were 187,875 per year for all types of examinations. Using published estimations for the mean effective dose for each type of examination, it was estimated that the collective dose from the above examinations was about 1,100 person-Sv, which, if projected to the total number of 152 CT scanners operating in Greece at the time of the survey, results in about 0.5 mSv per caput dose each year for the Greek population, which is probably the highest in Europe.

The diagnostic X-ray protection characteristics of Ytong, an aerated concrete based building material.

Ytong is a widely used building material. The X-ray attenuation properties of Ytong for broad beam geometry conditions and for tube potentials in the 50-140 kVp range are investigated. Comparisons with published data for concrete and other building materials are made. The results suggest that Ytong is not suitable for primary X-ray shielding in common diagnostic installations. However, walls of Ytong, typically 15-20 cm thick, may offer adequate protection in dental and mammography installations, as well as in low workload diagnostic installations as a secondary barrier.

Somatostatin receptor scintigraphy of non-neuroendocrine malignancies with 111In-pentetreotide.

In-111 pentetreotide is a new radiolabelled [OctreoScan 111, Mallinckrodt Medical BV, Petten] somatostatin analog with high affinity to somatostatin receptors (SR). introduced for the in vivo imaging of SR positive tissues. In an attempt to evaluate its clinical usefulness for tissue characterization in malignancies without neuroendocrine expression in parallel with histological and radiological examinations, specific scintigraphy was performed on brain (6 cases), thyroid (6 cases) and breast (9 cases) tumors, and in lymphomas (9 cases) and melanomas (6 cases). A dose of 111MBq of In-111 pentetreotide was injected i.v. to each patient and scintimages at 6 and 22 hours (for comparison) p.i. were obtained. The primary lesion of the breast cancer population was imaged in all 9 cases as well as all the palpable axillary nodes in 4 cases. Three women with impalpable axillary lymph nodes scanned negative but had a positive biopsy. Both meningiomas were positive for SR scans: positive results were also obtained for the high grade astrocytoma and the craniopharyngioma: Two out of 6 patients with papillary thyroid cancer showed a marked radiotracer accumulation. Scintigraphy in all 5 lymphomas was positive for SR but did not detect the Tc-99m sulphur microcolloid [Lymphoscint, Solco, Basel, Suitzerland] imaged lymph nodes in 5 melanomectomized patients. When judging the imaging results of these non-neuroendocrine malignancies definite conclusions should not be drawn since the number of studied cases polymorph, was small for every cancer histotype; nevertheless SR scintigraphy does not seem to be reliable for tumor staging in non-neuroendocrine malignancies, but is more suitable for a tissue characterization and monitoring changes of SR expression during and after therapy.

Rhenium-186-HEDP palliative treatment in disseminated bone metastases due to prostate cancer.

Prostate carcinoma is the most commonly associated with osseous metastases malignancy in males. The lesions, being usually of a mixed sclerotic/lytic variety and less often of the pure sclerotic type, need to be treated by a bone seeking radioactive element with an as low as possible radiobiological burden on the surrounding (peritumoral) tissues. Rhenium-186-HEDP was used to treat these osseous metastatic lesions due to its bone seeking kinetics attractive radiochemical properties. Of a total of 16 prostate cancer patients. 3 experiment loss of pain, 8 experienced obvious and 2 some improvement. No change was observed in 3 patients. Ten patients manifested a flare syndrome increasing pain approximately 2 to 6 days, after Re-186-HEDP i.v. application. Six patients showed a definite and 9 a slight decrease in platelet levels and absolute number of polymorphonuclear white blood cells, up to fourth week following treatment. One patient underwent a whole blood transfusion and in 2 peripheral neuropathy was observed lasting about 9 to 12 days. Re-186-HEDP appears to be a promising new metal ion complex for the palliation of painful bone metastases in prostate cancer. Compared to Sr-89 therapy, it shows a longer analgetic efficacy and has the advantage of emitting gamma rays, a fact which facilitates dosimetric calculations.

Palliative therapy using rhenium-186-HEDP in painful breast osseous metastases.

The efficacy and toxicity of treatment with 1400 +/- 100 MBq of Re-186-HEDP were evaluated in women with osseous metastatic breast cancer. The follow-up period was fourteen weeks. The efficacy of treatment was assessed by a) a pain and performance questionnaire that patients were asked to complete daily and b) a CT scan comparison of a randomly preselected osseous lesion before and 30 weeks after Re-186-HEDP i.v. application. The response to treatment was also evaluated by using the Kamofsky Index. Two out of fourteen women (14%) experienced loss of pain, 6 experienced obvious and 2 some improvement. No change was observed in 4 patients. Five patients manifested a flare response to treatment, with increase in pain within the first, 4 to 5 days after Re-186-HEDP administration. Five patients showed a decrease in platelet levels and absolute number of polymorphonuclear blood transfusion; no neurologic side effects were observed. Re-186-HEDP appears to be a useful new radiopharmaceutical for pain palliation induced by osseous metastases due to breast cancer. Compared to Sr-89 chloride efficacy, it provides longer-lasting analgesia, and when needed it can be reinjected with less risk due to its improved physico- and radiochemical properties.

Effects in the testes after SPECT myocardial perfusion with Tl-201 or Tc-99m hexaMIBI.

Thallium-201 with a half-life of 73 hours, decays by electron capture and as a consequence emits numerous Auger electrons. When it localises in the cell nucleus it causes enhanced biological effects. Technetium-99m with a half-life of 6 hours, radiates gamma rays and the side effects are not as significant. Tl-201 and Tc-99m labelled with SESTAMIBI are used for the SPECT perfusion image of the heart. In this study the tissue of interest are the testes which, after irradiation, can develop stochastic effects: both somatic (cancer) and hereditary. The activities of the radiopharmaceuticals used in common practice (30 mCi of Tc-99m and 3 mCi of Tl-201) cause different probabilities for the induction of stochastic effects in the testes. The probabilities are about 30 times higher for Tl-201 than for Tc-99m. These results, in combination with the fact that the higher activity of Tc-99m yields better images within shorter time, must make the clinician carefully assess the choice of the radiopharmaceutical to be used for the studies of the heart, especially for patients of reproductive age.

Prediction of tumor absorbed dose by Tc-99m-MDP scintigraphy prior to treatment with Sr-89.

A first order approximation of the tumor absorbed dose prior to treatment with Sr-89 was attempted in three patients treated for metastasized prostate carcinoma. All patients underwent bone scanning with Tc-99m-MDP two days before the administration of Sr-89, and a number of sequential quantitative images were obtained over the first 8 hours after Tc-99m-MDP injection. The collected data were used to derive an individualized Sr-89 time retention curve. Dosimetric estimations were subsequently based on the model described by ICRP Publ.30 (1979). In the present study a simplified model for the kinetics of both Sr-89 and Tc-99m-MDP was assumed. Normal adult data on the retention time of the two radiopharmaceuticals in the whole skeleton were combined and a linear relationship was derived between the time required for the same percentage uptake of the two radiopharmaceuticals after a single injection. The same relationship was assumed to hold for metastatic sites. The estimated absorbed dose in the principal metastases of the three patients, as well as normal bone of the same type and volume, is reported. A first order approximation of the absorbed dose by the skeleton is provided by the proposed method, before the therapeutic application of Sr-89 chloride using a diagnostic Tc-99m-MDP bone scan. The method is useful, simple, inexpensive and can be routinely performed.

Receptor scintigraphy of non-neuroendocrine cancers with In-111 pentetreotide.

Somatostatin receptors (SR) are surface markers characterizing not only APUDomas associated with neuroendocrine identities but also malignancies without neuroendocrine expression. Recently, the somatostatin analog pentetreotide was labeled with In-111 (OctreoScan 111, Mallinckrodt Medical BV, Petten, Holland) and introduced for the in vivo visualization in man of SR-positive tissues. In the present report, SR-specific scintigraphy is evaluated as a clinical tool for tissue characterization in correlation with histological and radiological examinations. Scintigraphy was focused and performed in cancer types without neuroendocrine tissue expression such as brain (n = 6) and breast tumors (n = 9) and lymphomas (n = 5). Scintigraphy was performed for comparison at 6 and 22 h after i.v. application of 111 MBq (3 mCi) of In-111-Pentetreotide. In the breast cancer group, the primary tumor was visualized in all 9 women as well as in all 4 cases with palpable axillary lymph nodes. Three women with a negative axillary node scan and impalpable nodes had positive biopsy. In two cases, mediastinal lymph node involvement was observed. So far the role of SR-positive breast cancer (BC) scans remains unknown. It is tempting to speculate that in resected women who are histologically and scintigraphically SR positive, it might be of value in the early detection of symptom-free recurrences. High densities of SR were present within both meningiomas, the high-grade astrocytoma and the craniopharyngioma. Differentiation of low- and high-grade astrocytomas could not be successfully achieved because both grades showed intense radioactivity uptake, even though high-grade tumors lack SR. The latter might be due to the damaged blood-brain barrier and the poor radioactivity washout observed in high-grade astrocytomas. All five lymphomas could be detected due to the presence of activated lymphocytes and macrophages that express SR at a sufficient density. In conclusion, SR scintigraphy in non-neuroendocrine malignancies does not seem to be reliable for an initial tumor staging but rather more suitable for a tissue characterization and extremely useful for monitoring changes of SR expression after treatment.

Automatic film processors' quality control test in Greek military hospitals.

The two major military radiology installations (Athens, Greece) using a total of 15 automatic film processors were assessed using the 21-step-wedge method. The results of quality control in all these processors are presented. The parameters measured under actual working conditions were base and fog, contrast and speed. Base and fog as well as speed displayed large variations with average values generally higher than acceptable, whilst contrast displayed greater stability. Developer temperature was measured daily during the test and was found to be outside the film manufacturers' recommended limits in nine of the 15 processors. In only one processor did film passing time vary on an every day basis and this was due to maloperation. Developer pH test was not part of the daily monitoring service being performed every 5 days for each film processor and found to be in the range 9-12; 10 of the 15 processors presented pH values outside the limits specified by the film manufacturers.