Biomedical subjects

Virginia Tsapaki

Publications and source records attributed to Virginia Tsapaki.

5 recordsLinked to original sources

PubMed2006

Dose reduction in CT while maintaining diagnostic confidence: diagnostic reference levels at routine head, chest, and abdominal CT--IAEA-coordinated research project.

PURPOSE: To measure radiation doses for computed tomography (CT) of the head, chest, and abdomen and compare them with the diagnostic reference levels, as part of the International Atomic Energy Agency Research coordination project. MATERIALS AND METHODS: The local ethics committees of all participating institutions approved the study protocol. Written informed consent was obtained from all patients. All scanners were helical single-section or multi-detector row CT systems. Six hundred thirty-three patients undergoing head (n = 97), chest (n = 243), or abdominal (n = 293) CT were included. Collected data included patient height, weight, sex, and age; tube voltage and tube current-time product settings; pitch; section thickness; number of sections; weighted or volumetric CT dose index; and dose-length product (DLP). The effective dose was also estimated and served as collective dose estimation data. RESULTS: Mean volumetric CT dose index and DLP values were below the European diagnostic reference levels: 39 mGy and 544 mGy . cm, respectively, at head CT; 9.3 mGy and 348 mGy . cm, respectively, at chest CT; and 10.4 mGy and 549 mGy . cm, respectively, at abdominal CT. Estimated effective doses were 1.2, 5.9, and 8.2 mSv, respectively. CONCLUSION: Comparison of CT results with diagnostic reference levels revealed the need for revisions, partly because the newer scanners have improved technology that facilitates lower patient doses.

Female↗

PubMed2006

Differentiated thyroid cancer: comparison of therapeutic iodine 131 biological elimination after discontinuation of levothyroxine versus administration of recombinant human thyrotropin.

The biological elimination of therapeutic 131I in patients with differentiated thyroid cancer (DTC), post total or near-total thyroidectomy, was compared after withholding levothyroxine suppression against administration of recombinant human thyrotropin without stopping levothyroxine. In 163 patients (group G1) levothyroxine was withheld before 131I therapy: in 138 patients the tumor was limited to the thyroid bed (group G1.1) and in 25 patients metastases were present (group G1.2). A second group of patients (G2; n = 28) received 131I therapy after administration of recombinant human thyrotropin without stopping levothyroxine. Mean retained 131I activity (as a percentage of the administered dose) was 5%-29% (group G1.1), 20%-43% (group G1.2) and 1%-17% (group G2). The effective half-life of 131I was 0.59-0.69 days (group G1.1), 0.87-1.22 days (group G1.2) and 0.38-0.44 days (group G2). In conclusion, the use of recombinant human thyrotropin to prepare patients with thyroid cancer for therapy with 131I shortens its effective half-life and reduces its retained activity compared to preparation with discontinuation of levothyroxine suppression.

Adolescent↗

PubMed2006

Factors that influence radiation dose in percutaneous coronary intervention.

AIM: To explore the factors that may influence the radiation dose imparted to the patient in PCI, and investigate whether the use of the latest digital X-ray system based on FP detector technology can have an impact on dose. MATERIALS AND METHOD: Demographic and clinical data such as number of lesions treated, number of stents placed, grade of tortuosity, and stage of occlusion, as well as use of double wire and double balloon technique, ostial stenting or bifurcation stenting, and presence of major complications were recorded, together with radiation parameters. RESULTS: The factors that increased patient radiation dose were (1) patient gender, as men exhibited higher doses than women; (2) complex lesion; (3) increasing number of stents; (4) position of stent; (5) grade of tortuosity; and (6) stage of occlusion. The FP digital system appeared to be settled in a lower-dose rate for fluoroscopy (a factor of 6) and higher for dose per frame in cine (a factor of 3) in comparison with the image intensifier (II) system. There was a marked reduction of DAP when the FP technology was introduced. CONCLUSION: More extensive studies should be performed in the future so as to further investigate the influence of the FP detector in IC.

Angioplasty, Balloon, Coronary↗

PubMed2004

Dose performance evaluation of a charge coupled device and a flat-panel digital fluoroscopy system recently installed in an interventional cardiology laboratory.

The purpose of the study was to evaluate the dose performance of a flat-panel (FP) and an image intensifier (II) charge coupled device (CCD) digital fluoroscopy X-ray systems newly installed in an Interventional Cardiology (IC) department. Filter entrance dose rate, detector dose rate (during fluoroscopy) and filter entrance dose per image were measured at 70 cm from the focus using 2 mm copper sheets to mimic normal size patient. Image quality was also evaluated. The patient dose survey included 277 patients, which had either a Coronary Angiography (CA) or a Percutaneous Transluminal Coronary Angioplasty (PTCA). Dose area product (DAP), fluoroscopy time (T) and total number of frames (F) values were also collected. The results showed that both systems performed within international recommendations with the exception of higher cine radiation doses, stressing the fact that neither specific protocols of measurement nor reference values for digital equipment were provided by the official bodies.

Cardiology↗

PubMed2004

Occupational dose constraints in interventional cardiology procedures: the DIMOND approach.

Radiation fields involved in angiographic suites are most uneven with intensity and gradient varying widely with projection geometry. The European Commission DIMOND III project addressed among others, the issues regarding optimization of staff doses with an attempt to propose preliminary occupational dose constraints. Two thermoluminescent dosemeters (TLD) were used to assess operators' extremity doses (left shoulder and left foot) during 20 coronary angiographies (CAs) and 20 percutaneous transluminal coronary angioplasties (PTCAs) in five European centres. X-ray equipment, radiation protection measures used and the dose delivered to the patient in terms of dose-area product (DAP) were recorded so as to subsequently associate them with operator's dose. The range of staff doses noted for the same TLD position, centre and procedure type emphasizes the importance of protective measures and technical characteristics of x-ray equipment. Correlation of patient's DAP with staff shoulder dose is moderate whereas correlation of patient's DAP with staff foot dose is poor in both CA and PTCA. Therefore, it is difficult to predict operator's dose from patient's DAP mainly due to the different use of protective measures. A preliminary occupational dose constraint value was defined by calculating cardiologists' annual effective dose and found to be 0.6 mSv.

Angioplasty, Balloon, Coronary↗