Abstract: This study presents an attempt to compare individualised palliative treatment absorbed doses, by planar images data and Monte Carlo simulation, in two in vivo treatment cases, one of bone metastases and the other of liver lesions. Medical Internal Radiation Dose schema was employed to estimate the absorbed doses. Radiopharmaceutical volume distributions and absorbed doses in the lesions as well as in critical organs were also calculated by Monte Carlo simulation. Individualised planar data calculations remain the method of choice in internal dosimetry in nuclear medicine, but with the disadvantage of attenuation and scatter corrections lack and organ overlay. The overall error is about 7 % for planar data calculations compared with that using Monte Carlo simulation. Patient-specific three-dimensional dosimetric calculations using single-photon emission computed tomography with a parallel computed tomography study is proposed as an accurate internal dosimetry with the additional use of dose-volume histograms, which express dose distributions in cases with obvious inhomogeneity.
Abstract: Single photon emission computed tomography (SPECT) imaging is widely implemented in nuclear medicine as its clinical role in the diagnosis and management of several diseases is, many times, very helpful (e.g., myocardium perfusion imaging). The quality of SPECT images are degraded by several factors such as noise because of the limited number of counts, attenuation, or scatter of photons. Image filtering is necessary to compensate these effects and, therefore, to improve image quality. The goal of filtering in tomographic images is to suppress statistical noise and simultaneously to preserve spatial resolution and contrast. The aim of this work is to describe the most widely used filters in SPECT applications and how these affect the image quality. The choice of the filter type, the cut-off frequency and the order is a major problem in clinical routine. In many clinical cases, information for specific parameters is not provided, and findings cannot be extrapolated to other similar SPECT imaging applications. A literature review for the determination of the mostly used filters in cardiac, brain, bone, liver, kidneys, and thyroid applications is also presented. As resulting from the overview, no filter is perfect, and the selection of the proper filters, most of the times, is done empirically. The standardization of image-processing results may limit the filter types for each SPECT examination to certain few filters and some of their parameters. Standardization, also, helps in reducing image processing time, as the filters and their parameters must be standardised before being put to clinical use. Commercial reconstruction software selections lead to comparable results interdepartmentally. The manufacturers normally supply default filters/parameters, but these may not be relevant in various clinical situations. After proper standardisation, it is possible to use many suitable filters or one optimal filter.
Abstract: The sleeping giant of molybdenum-99 ((99)Mo) production is grinding to a halt and the world is wondering how this happened. Fewer than 10 reactors in the world are capable of producing radio nuclides for medicine; approximately 50% of the world's supply of raw material comes from National Research Universal (NRU) reactor in Canada. Many of these reactors, like the NRU, are old and aging. No one of these reactors, and probably not even all of them in combination, can replace the production of NRU. As the healthcare industry faces an aging population and the demand for diagnostic services using (99m)Tc continues to rise, the need for a consistent, reliable supply of (99)Mo has become increasingly important, so alternative methods to produce (99)Mo or even directly (99m)Tc had to be considered to avoid a supply shortage in the coming years. This need guides to the production of (99)Mo by replacing the Highly Enriched Uranium (HEU) target in a nuclear reactor with Low Enriched Uranium (LEU) and furthermore to the use of accelerators for manufacturing (99)Mo or for directly producing (99m)Tc.
Abstract: (111)In (Eγ = 171-245 keV, t1/2 = 2.83 d) is used for targeted therapies of endocrine tumours. An average activity of 6.3 GBq is injected into the liver by catheterisation of the hepatic artery. This procedure is time-consuming (4-5 min) and as a result, both the physicians and the technical staff involved are subjected to radiation exposure. In this research, the efficiency of the use of lead apron has been studied as far as the radiation protection of the working staff is concerned. A solution of (111)In in a cylindrical scattering phantom was used as a source. Close to the scattering phantom, an anthropomorphic male Alderson RANDO phantom was positioned. Thermoluminescent dosemeters were located in triplets on the front surface, in the exit and in various depths in the 26th slice of the RANDO phantom. The experiment was repeated by covering the RANDO phantom by a lead apron 0.25 mm Pb equivalent. The unshielded dose rates and the shielded photon dose rates were measured. Calculations of dose rates by Monte Carlo N-particle transport code were compared with this study's measurements. A significant reduction of 65 % on surface dose was observed when using lead apron. A decrease of 30 % in the mean absorbed dose among the different depths of the 26th slice of the RANDO phantom has also been noticed. An accurate correlation of the experimental results with Monte Carlo simulation has been achieved.
Abstract: This article presents and discusses new information on the old Hippocratic moto of "...not to harm but to benefit the patient". Some radiation accidents are due to medical errors. Millions of medical tests exposing radiation are performed every day worldwide increasing and sometimes exceeding the annual permissible dose administered to the general population. Public authorities are now seriously concerned about medical radiation overused. In U.S.A. both the House of Representatives and the Food and Drug Administration have recently delt with this problem. Others and we have suggested before and the International Atomic Energy Agency now proposes: a "Smart Card" for every individual who receives medical radiation. In this card the amount of medical radiation administered will be recorded. It is time to issue rules for protection of the public from medical radiation overdose.
Abstract: Absorbed dose calculations in diagnostic applications using ionizing radiation are more accurate today than in past times. In this work we aim to demonstrate the methods used to calculate the absorbed dose of X-rays mammography and scintimammography. Absorbed dose estimation is achieved by calculations for internal dosimetry using Medical Internal Radiation Dose (MIRD), or Monte Carlo techniques, measurements in phantoms for mammography as well as patient specific calculations exploiting scintigraphic images' data. Especially, the accurate calculation of the absorbed doses during diagnostic examinations of the breast gives the possibility of evaluation of the danger of the use of ionizing radiation for this organ. Optimization of used techniques points to the reduction of the radiation burden of the examined person, by these screening tests. As the radio sensitivity of breast is high, the selection of an accurate absorbed dose calculation method is necessary. The weighting factor for breast is 0.12. This is the maximum value of the weighting factor for the various organs of the human body. Consequently, a detailed study of absorbed dose in breast, either in mammography or scintimammography, is crucial.
Abstract: Scintimammography is sometimes referred as a complementary diagnostic method to X-rays mammography and is the optimum examination for some patients to check suspected breast tumors. A dosimetric comparison of these diagnostic examinations is important. Estimation of the absorbed dose was achieved by calculations of internal dosimetry by Medical Internal Radiation Dose (MIRD) models and by calculations from the patients' scintigraphic images data using the MIRDOSE 3 program. The aim of this work was to compare the absorbed dose in scintimammography to that of X-rays mammography. Our results showed, that the breast absorbed dose by scintimammography examination using technetium-99m ((99m)Tc) complexes, 1.28mGy for (99m)Tc (V)-DMSA, 1.57mGy for (99m)Tc- MIBI and 1.92mGy for (99m)Tc-tetrofosmin, is considerably lower than the absorbed dose by scintimammography with thallium-201 chloride ((201)Tl-Cl) which reaches the 4.52mGy, or the absorbed dose by X-rays mammography. The absorbed mean glandular dose (MGD) for breast by X-rays mammography, taking 2 projections per breast, may reach 4.5mGy and is much higher for dense or large breasts. The European guidelines for quality assurance in breast cancer screening and diagnosis (2006, 4th edition) include a desirable level of less than 2.0mGy and an acceptable level of less than 2.5mGy for MGD for pressed breast thickness 4.5cm, per projection. In many radiology laboratories, specific care for every patient's radiation protection rules may reduce the MGD up to 1.4mGy per projection. Breast absorbed MGD in scintimammography by (99m)Tc-complexes mentioned above is reduced to more than half the above mentioned values for the examined breast and significantly lower than these levels for the not-examined breast. The radiation burden during scintimammography is also, many times lower than that of other radiology examinations including, lumbar spine radiography and pyelography. In conclusion, scintimammography is a low dose diagnostic method, and having also a high sensitivity, may be used as a complementary screening test in cases of dense breasts or breasts after surgery or breasts with prostheses, decreasing the necessity for breast biopsies.
Abstract: PURPOSE: The aim of this study is to evaluate the effectiveness of (111)In-DTPA-Phe(1)-octreotide infusions after selective catheterization of the hepatic artery in inoperable metastasised liver, sst(2) receptor-positive neuroendocrine tumours due to the effect of (111)In Auger electron emission, minimising in parallel the toxicity of non-target tissue. METHODS: The average dose per session administered monthly to each patient (17 cases in total) was 6.3+/-2.3 GBq. Repetitions did not exceed 12-fold, except in one case (15 sessions). Response assessment was classified according to the Response Evaluating Criteria in Solid Tumours. CT/MRI scans were performed as baseline before, during and after the end of treatment, and monthly ultrasound images for follow-up measurements. Toxicity (World Health Organization criteria) was measured using blood and urine tests of renal, hepatic and bone marrow function. RESULTS: Complete response was achieved in one (5.9%) patient and partial in eight (47.0%), and disease stabilization in 3 (17.7%) patients; five (29.4%) did not respond. A 32-month median survival time was estimated in 12 (70.5%). Nine of these 12 surviving had a mean target diameter shrinkage from 144+/-81 to 60+/-59 mm. Grade 1 erythro-, leuko- and thrombo-cytopenia occurred in three (17.6%) cases. CONCLUSION: In unresectable metastatic liver lesions positive for somatostatin receptors repeated, transhepatic high doses of (111)In-DTPA-Phe(1)-octreotide show an effective therapeutic outcome. Given the locoregional modality character of the administration technique plus the extremely short range of (111)In Auger and internal conversion electrons emission, no nephro-, liver- or myelo-toxicity has so far been observed.
Abstract: Thirteen (13) patients with liver neuroendocrine carcinomas metastases, positive for somatostatin receptors, confirmed by scintigraphy were infused with 4070-7030 MBq per session of In-111-octreotide after selective hepatic catheterization, exploiting the catastrophic activity of Indium Auger and Internal Conversion electron emission on cell DNA. Evaluation of the treatment was assessed by ultrasonography (US) as well as by computed tomography and/or magnetic resonance imaging scans. US appears to be the imaging procedure of choice because the examination is sensitive for evaluating lesions' edema and cystic components, provides precise measurement of tumor size, and is inexpensive. Degeneration US signs were classified in stage I (an echolucent rim in the periphery of the lesion), stage IIa (lesion with large cystic spaces), stage IIb (tiny cystic spaces) and stage III (absorption of the cystic component or stable cystic remnants).
Abstract: 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.
Abstract: BACKGROUND: Somatostatin is a naturally occurring hormone widely identified in a number of human tissues, with a broad spectrum of physiological actions. Octreotide is a synthetic analogue of somatostatin, which seems to be promising in clinical use. AIMS: a. to evaluate the efficacy of octreotide in pain control of patients with advanced gastrointestinal cancer, as well as octreotide's outcome in the hepatic function; b. to investigate the relationship between pain intensity and beta-endorphin blood levels in the patients. PATIENTS: The study group consisted of 25 patients (age range: 48-89 years, 14 males, 11 females) with far advanced gastrointestinal cancer. METHODS: All the patients were under s.c. morphine administration using a continuous infusion pump. When pain intensity increased, 0.6 mg/day of octreotide was added to the therapeutic regimen in the same syringe of the continuous infusion pump. Pain intensity and beta-endorphin blood levels were measured five times: Once before octreotide administration and the other four 12, 24, 48 hours and 7 days after. A complete blood count and a biochemical screening profile were taken before the administration of octreotide as well as on the 7th and the 14th day. RESULTS: 24 out of 25 cases showed a reduction in pain intensity (pretreatment x = 5.3, post-treatment x = 0.6). beta-endorphin blood levels increased significantly during the study (an increase of 184.78% was observed on the 7th treatment day). In one patient pain control was achieved by increasing morphine dosage. Statistically significant changes were observed in hepatic function indices (p < 0.02). Significant side-effects were not observed. CONCLUSION: Octreotide can be used as an adjuvant analgesic in the management of gastrointestinal cancer pain which is managed by continuous s.c. administration. Although fuither research needs to be done, octreotide's administration seemed to improve hepatic function of these patients, therefore, it could potentially have a positive effect in the patient's quality of life.
Abstract: 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.
Abstract: The accident which occurred during the night of April 25-26, 1986 in reactor 4 of the Chernobyl nuclear power plant in the Ukraine released considerable amounts of radioactive substances into the environment. Outside the former USSR, the highest levels of contamination were recorded in Bulgaria, Austria, Greece and Romania, followed by other countries of Central, Southeast and Northern Europe. Studies of the health consequences of the accident have been carried out in these countries, as well as in other countries in Europe. This report presents the results of a critical review of cancer studies of the exposed population in Europe, carried out on the occasion of the 10th anniversary of the Chernobyl accident. Overall, three is no evidence to date of a major public health impact of the Chernobyl accident in the field of cancer in countries of Europe outside the former USSR.
