Technetium Tc-99m red blood cells (Cadema Corp.)

In a Nuclear Medicine department, the risk of external and internal contamination in radiation workers is much higher than in other medical radiation facilities. The risk associated with both types of contaminations should be quantified to estimate the radiation dose received by the personal. Here, we designed an in vitro model to see the impact of internal and external contamination of F-18 and Technetium-99 m (Tc-99 m) on DNA damages.

Chinese hamster lung fibroblast V79 was used for all of the experiments. Irradiation was performed internally and externally (scenarios activity is mixed with the cell line [Internal] and activity kept at 1 cm distance from cell line [external]) using two different diagnostic radioactive sources (Tc-99 m and F-18) of known quantity 37 MBq. Total cumulated activity (MBq-min) was calculated up to one half-life of sources for both internal and external setups. An alkaline single gel electrophoresis technique (comet assay) was used for DNA damage analysis. Olive tail moment (OTM) was used to characterize DNA damage.

We have not observed any significant difference (P > 0.05) in OTM between internal and external irradiation for cumulated activity presented before one half-life of both diagnostic isotopes. However, a significant difference in OTM was noted between internal and external irradiation for cumulated activity presented at one half-life of radioactive sources (P < 0.05). DNA damage with internal exposure was found to be 17.28% higher for F-18 and 23% higher for Tc-99 m than external exposure at one half-life of radioactive sources. Overall, we noted greater DNA damage in F-18 as compared to Tc-99 m.

Our in vitro study practically demonstrated that internal contamination is more hazardous than external exposure.

Hepatectomy represents the first choice of treatment for primary and secondary liver malignancies.However,post-hepatectomy liver failure(PHLF) remains a significant cause of morbidity and mortality after liver resection.Inadequate remnant liver volume and function are the determining factors of PHLF.Therefore,preoperative assessment of hepatic functional reserve is of paramount importance for prevention of PHLF.There are two main conventional assessment systems of preoperative hepatic functional reserve.The first is remnant liver volume(RLV) and its derivative indicators such as residual liver volume ratio,standardized residual liver volume ratio,RLV/body weight,and RLV/body surface area,calculated by imaging-based methods such as CT,that assess whether the volume of residual liver meets the requirements of safe hepatectomy.However,RLV is not an appropriate indicator of functional liver remnant,since the function of liver within equal volume among different persons is unequal due to the underlying liver diseases.Functional imaging techniques,such as ⁹⁹Tc^m-GSA,⁹⁹Tc^m-IDA and Gd-EOB-DTPA-enhanced MRI can simultaneously evaluate residual liver volume and function,leading to be a more appropriate indicator of functional liver remnant.The second is liver function tests,including serum biochemical parameters,clinical scoring systems and quantitative liver function tests.However,it can merely evaluate the overall liver function preoperatively,but not the residual one postoperatively.The residual liver function can be accurately measured by intraoperative indocyanine green clearance with the extrahepatic and intrahepatic blood flow of liver to be resected blocked.In addition,methods such as preoperative portal vein embolization and associating liver partition and portal vein ligation for staged hepatectomy,can be used for patients with a predicted inadequate RLV.Due to the unequal liver function within an equal volume increased by different methods,functional imaging techniques are more appropriate in predicting the increasing functional liver than traditional methods which just assess the increasing liver volume.