Preparation and validation of [67Ga]Ga-phytate kit and Monte Carlo dosimetry: an effort toward developing an impressive lymphoscintigraphy tracer

Evaluation of 188Re- IBA as a novel radiopharmaceutical for bone marrow ablation

In this study, Ibandronate as a third generation of bisphosphonates was labeled with rhenium-188 radionuclide. Production and quality control of 188Re-IBA radiopharmaceutical was investigated. The radiation absorbed dose of this radiopharmaceutical was evaluated for adult male based on biodistribution data in mice using the RADAR and Sparks and Aydogan methodologies. The 188Re-IBA was produced with more than 96% radiochemical purity. The highest value of %ID/g was related to bone with 7.11% at 12 h post-injection. About 48% of injected activity was cumulated on the surface of bone tissue 48 h post-injection. The imaging studies confirmed the biodistribution pattern. Radiation absorbed doses of red bone marrow and osteogenic cells were estimated to about 0.39 and 0.71 mGy MBq-1, respectively. The maximum administrated activity was obtained 73.1 MBq kg-1 (2.0 mCi kg-1) of body weight. Effective dose was evaluated about 0.09 mSv MBq-1. The results were compared with other clinically used bone pain palliation radiopharmaceuticals. It was concluded that the 188Re-IBA radiopharmaceutical has a great tendency to be absorbed in bone tissue and it can provide sufficient care for bone marrow ablation with low undesired dose to other normal organs.

Comparison of absorbed doses to the tumoral and non-tumoral liver in HCC patients undergoing 99mTc-MAA and 90Y-microspheres radioembolization

PURPOSE

This study aimed to determine the absorbed doses in the tumoral-liver and non-tumoral liver of hepatocellular carcinoma (HCC) patients undergoing radioembolization with Yttrium-90 (90Y) resin microspheres, and compared with those derived from 99mTc-MAA using the partition model.

METHODS

A total of 42 HCC patients (28 males and 14 females, mean age 65 ± 11.51 years) who received 45 treatment sessions with 90Y-microspheres between 2016 and 2021 were included. Pre-treatment 99mTc-MAA and post-treatment 90Y-bremsstrahlung SPECT/CT were acquired for each patient. Semi-automated segmentation of regions of interest (ROIs) was performed using MIM Encore software to determine the tumor-liver ratio (TLR) encompassing the liver volume, tumoral-liver, and lungs, and verified by both nuclear medicine physician and interventional radiologist. A partition dosimetry model was used to estimate the administered activity of 90Y-microspheres and the absorbed doses to the tumoral-liver and non-tumoral liver. The student's paired t test and Bland-Altman plot were used for the statistical analysis.

RESULTS

The mean TLR values obtained from 99mTc-MAA SPECT/CT and 90Y-bremsstrahlung SPECT/CT were 4.78 ± 3.51 and 2.73 ± 1.18, respectively. The mean planning administered activity of 90Y-microspheres based on 99mTc-MAA SPECT/CT was 1.56 ± 0.80 GBq, while the implanted administered activity was 2.53 ± 1.23 GBq (p value < 0.001). The mean absorbed doses in the tumoral-liver estimated from 99mTc-MAA and 90Y-bremsstrahlung SPECT/CT were 127.44 ± 4.36 Gy and 135.98 ± 6.30 Gy, respectively. The corresponding mean absorbed doses in the non-tumoral liver were 34.61 ± 13.93 Gy and 55.04 ± 16.36 Gy.

CONCLUSION

This study provides evidence that the administered activity of 90Y-microspheres, as estimated from 90Y-bremsstrahlung SPECT/CT, was significantly higher than that estimated from 99mTc-MAA SPECT/CT resulted in increased absorbed doses in both the tumoral-liver and non-tumoral liver. However, 99mTc-MAA SPECT/CT remains a valuable planning tool for predicting the distribution of 90Y-microspheres in liver cancer treatment.

Internal dosimetry of 64Cu-DOX-loaded microcapsules by Monte Carlo method

Some of the issues regarding introducing new radiocompounds in nuclear medicine are the distribution patterns, delivered dose to different organs, diagnostic abilities and side effects. In this study, in order to assess the biodistribution of ⁶⁴Cu-DOX-loaded microcapsules, rats were IV-injected with the microcapsules, and 1, 4, 14, and 24 h later, the activities of the targeted organs were measured (%ID/g). The accumulated activities were achieved by %ID/g curves, and S-factors were obtained by MCNP outputs. The MIRD formulation and Monte Carlo method were used to determine the absorbed dose in the target organs. The biodistribution data and PET-CT images showed that the lungs were where the majority of activity was seen. According to MIRD and MCNP, the maximum dose delivered in the lungs was 5.79E+01 mGy/MBq and 4.70E+01 mGy/MBq, respectively. Also, the effective dose was 1.2E+01 for MIRD and 8.31E+00 mSv/MBq for MCNP. These results indicate that ⁶⁴Cu-DOX microcapsules can be considered a new radiocompound in pulmonary imaging, and MCNP simulation can be a reliable method for internal dosimetry.

A Review of Nuclear Medicine Approaches in the Diagnosis and the Treatment of Gynecological Malignancies

Nuclear medicine is defined as the diagnosis and the treatment of disease using radiolabeled compounds known as radiopharmaceuticals. Single-photon emission computed tomography/computed tomography (SPECT/CT) and positron emission tomography/computer tomography (PET/CT) based radiopharmaceuticals have proven reliable in diagnostic imaging in nuclear medicine and cancer treatment. One of the most critical cancers that also relies on an early diagnosis is gynecological cancer. Given that approximately 25% of all cancers in developing countries are a subset of gynecological cancer, investigating this cancer subtype is of significant clinical worth, particularly in light of its high rate of mortality. With accurate identification of high grade distant abdominal endometrial cancer as well as extra abdominal metastases, 18F-Fluorodeoxyglucose ([18F]FDG) PET/CT imaging is considered a valuable step forward in the investigation of gynecological cancer. Considering these factors, [18F]FDG PET/CT imaging can assist in making management of patient therapy more feasible. In this literature review, we will provide a short overview of the role of nuclear medicine in the diagnosis of obstetric and gynecological cancers.