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M Vrtar

Publications and source records attributed to M Vrtar.

15 recordsLinked to original sources
PubMed1998

A model of in vivo dosimetry and quality assurance analysis of total body irradiation in Zagreb.

The aim of the study was to develop a systemic and simple method for determination of midplane dose factors and lung correction factors, suitable for semiconductor 60-Co total body irradiation (TBI) in vivo dosimetry, based on input (entrance) and output (exit) dose readings. A theoretical model of anthropomorphic phantoms of cylindrical ellipsoid shape made it possible to generalize the applicability to any individual case of the real patient's data. Also, the quality assurance analysis of dosimetric results of 230 patients who had undergone TBI during a 10-year period, was performed. The ratio of the mean measured dose values for all locations in all patients and stated dose (12.45 Gy in 3 days, 3 fractions) was 0.998, SD 0.033. The upper limit of the total combined uncertainty of TBI midplane absorbed dose, including all locations and all sources of error, amounted to 9.4%.

Humans↗
PubMed1994

Lung correction and mid plane irradiation dose factors in anatomic phantoms of proportional sizes.

In vivo dosimetry in combined anterior-posterior, posterior-anterior, total body irradiation (AP-PA TBI) with Co-60 units makes it possible to determine the absorbed dose (D) in the patient's mid plane by means of an entrance dose reading (R) multiplied by a Mid Plane Dose Factor (MDF) and a Lung Correction Factor (CF). A theoretical model of an anatomic phantom, based on a number of cylindrical ellipsoide which could be set in any order following a real therapeutical position, was established. The dimensions of the constituent parts were variable and subject to change. In this work, calculations in the reference phantom with volume VO were compared with measurements in two experimental anatomic phantoms of the same volume and shape; 1. a water phantom from the former investigations and 2. a polystyrene phantom based on real patients' CTs with the lungs' inhomogeneities. A generalisation to proportional phantom sizes with volume V was set up. It was found that in this approach the ratio V/Vo had a significant role in the determination of MDF and CF, when real scattering conditions, e.g. lack of scatter due to the finite phantom width, were included.

Humans↗
PubMed1992

Total body irradiation with or without lung shielding for allogeneic bone marrow transplantation.

From June 1986 to June 1990, 64 patients with leukaemia (25 acute myelogenous leukaemia, 21 acute lymphoblastic leukaemia and 18 chronic myeloid leukaemia) undergoing marrow transplantation were randomized to receive cyclophosphamide (CY) and fractionated total body irradiation (TBI) without lung shielding (n = 33) or CY and fractionated TBI with lung shielding (n = 31, control group) as conditioning. Patients conditioned with TBI without lung shielding received a significantly higher total lung dose compared with the control group (p less than 0.0001). The 3-year leukaemia-free survival for patients receiving TBI without lung shielding is 54 +/- 18% versus 51 +/- 18% for patients receiving TBI with lung shielding (p = ns). There was no significant difference in the probability of leukaemia relapse (22 +/- 18% for TBI without lung shielding versus 24 +/- 18% for control group; p = ns). The probability of interstitial pneumonitis is 15 +/- 14% for TBI without lung shielding and 5 +/- 5% for TBI with lung shielding (p = ns). A higher incidence of lung fungal infection (15 versus 3%) and interstitial pneumonitis (12 versus 3%) has been documented in patients receiving TBI without lung shielding compared with the control group. The results indicate that higher radiation dose to the lung did not increase antileukaemic efficacy of TBI but seemed to be associated with the increased pulmonary toxicity.

Adult↗
PubMed1991

Local tissue air ratio in an anatomic phantom for 60Co total body irradiation.

Tissue-air ratio (TAR), as the basic dosimetric function, is not ideally applicable to all important locations in total body irradiation (TBI) dosimetry because it generally refers to central ray measurements. We therefore introduced the local TAR which depends on the specific distribution of the scattering centres around the location of interest. Local TAR measurements were performed in an anatomic water phantom, produced by a sculptor, representing a patient during TBI in the real treatment position. A comparison has been made between TAR values, defined on the beam's ray at different locations in the anatomic phantom and cubic phantoms of different size. The local TAR values in the anatomic phantom, having more realistic outer surface curvatures, are lower by a few percent in most locations. We consider these values more accurate and better applicable to TBI conditions than those obtained in cubic water phantoms, even if the volume of the phantom is adapted to the particular side of the body.

Air↗
PubMed1986

Cyclosporin neurotoxicity in patients treated with allogeneic bone marrow transplantation.

Toxicity to the central nervous system was observed in 3 out of 15 patients receiving cyclosporin prophylaxis for graft-versus-host-disease after allogeneic bone marrow transplantation. Neurological clinical features included grand mal seizures, dysarthria and vestibular and cochlear toxicity. In all three patients, cyclosporin plasma levels were increased at the time of overt clinical neurological signs. The symptoms resolved quickly with the reduction of the cyclosporin dose.

Adult↗
PubMed1986

Experience with bone marrow transplantation for severe aplastic anemia and leukemia. Two years experience with 31 patients in Zagreb (Yugoslavia).

Since 1983, twelve patients with severe aplastic anemia and nineteen patients with leukemia were treated with bone marrow transplantation. Six patients with severe aplastic anemia are still alive at 300 to 1,210 days after transplantation, and twelve patients with leukemia are alive at 199 to 671 days. The incidence of GvHD was relatively high (60%). Bacterial infections were the main causes of death.

Adolescent↗
PubMed1978

Ultrasonic planimetry of the gestation sac as a biometric method in early pregnancy.

A new method for determining the area of the gestation sac by thread planimetry is described. Mean weekly values with two standard deviations were determined on a series of 237 measurements of gestation sac area, age five to 11 weeks, in normal pregnancies. The gestation sac area grows curvilinearly from 1.85 cm2 at five weeks to 15 cm2 at 11 weeks. The mean diameter was calculated from the gestation sac area by using an adequate approximation of the irregular gestation sac shape to a circle of the same area. The dependence of the mean gestation sac diameter on gestation age is defined by the regression equation y = 0.46x - 0.95 and the correlation factor r = 0.92. Practical applications of gestation sac planimetry include the determination of gestation age in early pregnancy, and the follow-up of growth or determination of delayed growth in disturbed or failed early pregnancy.

Biometry↗
PubMed1978

Ultrasonic calculation of chorion cavity volume.

A method for calculating chorion cavity volume in the first trimester of pregnancy from the ultrasonic projection of the gestation sac is described. The area of the longitudinal and transverse sections were measured, and the volume was calculated from the mean value of the two measurements. The chorion cavity volume increased curvilinearly and approximately exponentially from 2.14 cc at five weeks to 44.38 cc at 11 weeks of gestation. The method was checked by comparing the computed volume and the real volume obtained surgically and by experimenting with an "artificial gestation sac" picture. A good correlation was obtained. The results match data reported in the literature.

Biometry↗
PubMedDate not supplied

[Treatment of neoplastic hematologic diseases with intensive radio-chemotherapy and transplantation of cryopreserved autologous bone marrow].

Autologous bone marrow transplantation (ABMT) allows application of intensive myeloablative therapy aimed at eradication of neoplastic disease by facilitating haematopoietic reconstitution. Between March and June 1988, four patients (two with acute myelogenous leukaemia in first remission, one with acute lymphoblastic leukaemia in second remission, and one with Burkitt lymphoma, stage IV with CNS involvement in second remission) received this treatment. Methods of collecting, processing and freezing bone marrow as well as thawing and reinfusion of the marrow into patients after intensive chemoradiotherapy are described. Viability of bone marrow cells tested by the dye exclusion method after freezing and thawing process was 89, 88, 91 and 78%, respectively. CFU-GM recovery in culture, as a test of marrow stem cells clonogenicity was between 63,3 and 156,5%. Patients received between 1,7 and 3,0 x 10(8)/kg nucleated cells and 4,0 to 7,6 x 10(4)/kg CFU-GM, respectively. In all four patients stable haematopoietic reconstitution was achieved. The bone marrow function was evident mainly at 11th day after marrow reinfusion. Leukocyte count reached 1,0 x 10(0)/L in 11 to 15 days, and granulocyte count raised more than 0,5 x 10(9)/L in 19 to 37 days after transplantation. Platelet recovery was prolonged with the minimum of 29 days and maximum of more than 60 days to reach 20 x 10(9)/L. Side effects caused by the intensive radiochemotherapy were moderate. Bacterial, fungal and viral infections in early posttransplant period were successfully treated. All patients have survived and left the hospital 63, 54, 36 and 65 days after ABMT, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Bone Marrow Transplantation↗