[Dosimetry in scintimammography by (99m)Tc-MIBI, (99m)Tc-Tetrofosmin, (99m)Tc-(V)DMSA and 201TlCl compared with X-rays mammography].

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.