Liquid embolisation material reduces the delivered radiation dose: a physical experiment.

OBJECTIVE: To test a new hypothesis that the glue/contrast admixture used for embolisation reduces the dose delivered to AVMs using an experimental model. METHOD: A model was created using a block of "solid water" (6 x 5 x 2 cm) with twelve wells of different depths. Different concentrations of the glue admixture (Enbucrilate + Lipiodol) were used. The model was irradiated using a 5MV beam with a clinical LINAC system and the dose was checked upstream and downstream. Dose was measured using Kodak XV film, a Vidar 16 bit film scanner and software for therapeutic film dosimetry measurements (RIT software). RESULTS: The radiation dose varied with the distance beyond the glue solid water interface. For distances of 0, 2 and 5 mm to the film, the mean reduction was 13.65% (SD = 2.94), 6.87% (SD = 1.95) and 1.75% (SD = 1.14), respectively. There was also correlation with the Lipiodol concentration in the mixture. The maximum reductions for 80, 50 and 20% Lipiodol concentrations were 16.1% (SD = 1.32), 14.85% (SD = 0.98) and 10% (SD = 1.21), respectively. There was no correlation between the glue depth and the dose delivered. CONCLUSION: The hypothesis that the glue mixture used for embolisation reduces the radiation dose delivered was experimentally confirmed with this study.

The effect of iodized oil on the TSH response to TRH in endemic goiter patients.

The TSH and T3 response to synthetic TRH was evaluated in 4 groups of patients: normal controls and goitrous subjects from the urban area of Sao Paulo (urinary iodine excretion: 172.2 +/- 48.3 mug I/g creatinine) and nongoitrous and goitrous subjects from the endemic areas of Sao Bento (urinary iodine excretion: 53.8 +/- 17.1 mug I/g). Plasma T4 and T3 were within our normal range in all groups of patients. The mean plasma TSH was significantly higher (5.2 +/- 3.3 muU/ml) in goitrous subjects living in Sao Bento as compared to normal control groups both in urban or endemic areas, and after TRH these patients had an exaggerated and sustained TSH response with a significantly higher peak level (21.1 +/- 7.9 muU/ml). T3 concentration rose in all subjects following TRH and all patients from the Sao Bento endemic areas had a significantly higher proportionate increase in plasma T3 at 120 min. After an injection of iodized oil basal plasma TSH returned to the normal range in the goitrous subjects from Sao Bento. The mean peak TSH response to TRH was 9.1 +/- 3.8 muU/ml at 3 months after the iodized oil injection, and only at 6 months after the iodized oil TSH response was significantly reduced (peak level: 6.1 +/- 2.4 muU/ml). It is confirmed that plasma TSH levels are increased in endemic goitrous patients but not in normal controls living in the same endemic area and it is suggested that the pituitary threshold for inhibition of secretion of TSH by T4 and T3 has been reset in these goitrous subjects to achieve a persistently higher secretion rate of TSH.

Effect of iodized oil on iodine content, thyroglobulin maturation and on biochemical constituents of endemic goitre in brazil.

The biochemical and morphological changes in thyroid glands were studied in 5 patients with endemic goitre in the region before and one year after the administration of iodized oil. Each patient received a tracer dose of 125-I 3-5 weeks before the biopsy and another tracer of 131-I 12 h before surgery. It was observed that: 1. Iodine deficient goitrous glands had more protein per gram of tissue and that this was corrected by iodination. 2. The goitrous glands exhibited a higher relative proportion of particulate iodoprotein that incorporates more labelled iodine in relation to time of labelling. This abnormal situation is reverted to normal by iodination. 3. A significantly higher proportion of T3 + T4 is synthetized by the glands treated with iodized oil. 4. The increased amount of 127-I per gram of tissue is followed by an increased iodination level of thyroglobulin. 5. The ultracentrifugal pattern of proteins observed for iodine deficient glands differed from the iodinated glands, indicating a failure of maturation of thyroglobulin and possibly a greater than normal degree of heterogeneity. 6. The shift in sedimentation pattern was clearly induced by the increased degree of iodination, as shown by the iodized oil injection. 7. The increased cellularity and the higher rate of protein synthesis in the goitrous glands are reverted to normal after the iodized oil injection.