Biomedical subjects

H Toivola

Publications and source records attributed to H Toivola.

4 recordsLinked to original sources

PubMed1992

Radiotherapy of malignant melanoma of the uvea with I-125 seeds.

Nineteen patients with malignant uveal melanomas were treated with I-125 applicators. There were 10 males and 9 females with a median age of 61 years (range 42-76). The tumour was located in the choroid in 12 eyes and in the choroid and ciliary body in 7 eyes. The size of the tumours was 7-18 mm in maximal basal diameter (median 12), 5-16 mm in minimal basal diameter (median 10), and 5.5-15 mm in thickness (median 8.5). The volume of the tumours was 123-1890 mm3 (median 540). All tumours were classified as large (T3). For the irradiation, a computer program, which calculates three-dimensional dose distribution of I-125 seeds in gold plaques, was developed. By modifying the seed positions, activity and the orientation, patients can be treated individually. Iodine-125 emits low energy photons, ideal for intraocular tumour therapy and tissue. Extra-ocular tissue located behind the applicator can be completely shielded by a 0.5 mm gold layer. The dose at the apex of the tumour ranged from 30 to 120 Gy (median 93). The treatment time ranged from 44 to 600 h (median 235). Preliminary results are good. After a median follow-up of 6 months, the tumour growth has been arrested in all eyes and in 10 eyes the tumour has decreased in size.

Adult↗

PubMed1989

Deflections in computed dose distribution of I-125 seed implant due to angularly averaged approximation.

Dose rate distribution of commercially available I-125 seeds is strongly anisotropic due to self absorption. Effects of this anisotropy to dose distribution of linear, planar and volume implants are studied. Results suggest that this anisotropy should be taken into account especially when one is considering dose distribution near the seeds. Angularly averaged distribution of single seed is found to cause serious deflections to isodoses of the implant in high dose region. To use true anisotropic dose rate distribution one must be able to evaluate angular orientation of seeds in the implant. A method is presented to compute this orientation also when seeds are poorly visible in radiographs.

Brachytherapy↗

PubMed1987

Alcohol and ambience: social and environmental determinants of intake and mood.

An experiment was conducted in which 66 male subjects were given access to alcohol (20% vol.) and fruit juice to be mixed and tasted ad lib. A factorial design included social vs. solitary drinking conditions, laboratory vs. informal setting, and variable exposure to music. The amount of ethanol consumed (g/kg body weight) was used as an unobtrusive measure of preferred intake. The reciprocal relationship between mood and consumption was analyzed by LISREL. While euphoria has usually been perceived as a consequence of drinking, the only plausible fit to a LISREL model was obtained by assuming that the disposition to drink would be increased by positive mood changes occurring during the drinking session. An analogy between social drinking and adjunctive behaviour was supported, as alcohol consumption was directly affected by time-dependent environmental factors such as company and music. Since the presence of company also stimulated positive mood and alleviated boredom, consumption was precipitated by company indirectly as well as directly. These results emphasize the importance of direct as well as indirect environmental influences on spontaneous alcohol intake during social drinking.

Adult↗

PubMed1987

A computer program for I-125 seed implant.

A computer program, written in FORTRAN, for I-125 permanent interstitial implants has been developed. After implantation, isocentric radiographs are taken using radiotherapy simulator (Siemens) in order to obtain two X-ray images of seeds on the same film. Honeywell DPS8 computer and Hewlett-Packard 7221A plotter are used for the dose calculation. The program calculates the dose distribution at the plane desired using 100 X 100 matrix.

Brachytherapy↗