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From Tracers to Treatment
Published in Alan Perkins, Life and Death Rays, 2021
The radioactivity turned out to be iodine-125 which has a half-life of 60 days and is commonly used in medical biochemistry units and university research laboratories. A total of 46 contaminated items were identified with a total activity of 28 MBq. The labelled playing card chips contained a total activity of 24.4 MBq. The maximum ambient dose rate was 12.6 mSv per hour at a distance of 10 centimetres from the back of the card. Detailed analysis of the gamma spectrum obtained showed that the iodine-125 was extremely pure, suggesting that it was obtained from material originally produced for medical use. It was subsequently estimated that the concentration of the iodine-125 solution used for marking the playing cards was in the range of 7 GBq to 20 GBq per millilitre. The amount of radioactivity recovered from the premises was not considered to be dangerous to health, although it could have resulted in some radioactive uptake in the thyroid glands of those handling the material. The German authorities ordered the contaminated areas to be sealed and cleaned but considered that there was no wider risk of contamination. The restaurant owner was charged for the environmental release of ionising radiation.
Evaluation of the Potential of Microspherical Systems for Regional Therapy in the Tumor-Bearing Liver and Kidney Using Techniques in Nuclear Medicine
Published in Neville Willmott, John Daly, Microspheres and Regional Cancer Therapy, 2020
Jacqueline A. Goldberg, James H. McKillop, Colin S. McArdle
Radioisotopes of iodine are widely used for radiolabeling of proteins.16 None are available from a generator. Iodine-123 has near-ideal gamma rays for gamma camera detection and a relatively short half-life, thus reducing patient radiation dose. It is suitable for imaging microsphere distribution, but because of the similarity in photon energies it cannot be used with 99mTc in dual-tracer studies. The major disadvantage of 123I relates to its lack of ready availability in many centers, the need to specifically order a tracer with a short half-life (and thus short shelf-life), and high cost. Iodine-125 (125I) is widely used for in vitro studies, including radioimmunoassay. The low energy photons make 125I completely unsuitable for gamma camera imaging or probe studies. It can be used, however, for studies involving tissue (or blood) sampling and in vitro counting. Because of radiation dosimetry, the activity administered to patients must be strictly controlled.
Prostate Cancer
Published in Manit Arya, Taimur T. Shah, Jas S. Kalsi, Herman S. Fernando, Iqbal S. Shergill, Asif Muneer, Hashim U. Ahmed, MCQs for the FRCS(Urol) and Postgraduate Urology Examinations, 2020
According to NICE guidelines brachytherapy is considered an option in low- and intermediate-risk groups. Iridium192 is the radioisotope used in high dose brachytherapy in combination with external beam radiotherapy. Iodine125 and palladium103 are used in low dose brachytherapy. Prostate volume of 50–60 mL is considered the upper limit for BXT treatment due to pubic arch interference preventing insertion of the source in some of the anterior gland.
Comet Assay analysis of DNA strand breaks after exposure to the DNA-incorporated Auger Electron Emitter Iodine-125
Published in International Journal of Radiation Biology, 2023
Marcus Unverricht-Yeboah, Kathrin Holtmann, Ralf Kriehuber
For low-LET γ-radiation, a SSB/DSB ratio of 10:1 was determined in SCL-II cells. In contrast, DNA-incorporated Iodine-125 induced a much lower SSB/DSB ratio of 6:1, which is in very good accordance with the calculated SSB/DSB ratio of 5.4:1 for I-125-UdR based on computer simulation by Pomplun et al. (1996). DNA-associated Iodine-125 seems to be far more efficient in the DSB production than low-LET radiation. This can be explained by the high energy deposition at the decay site of Iodine-125 which will generate multiple strand breaks in the DNA double helix in the close vicinity of the AEE. Thus, closely opposed SSB convert easily into a DSB. In addition, the induction of closely opposed SSB is very likely for high-LET particle radiation as well, as a large amount of ionizing events occur along the track in a rather small volume. Thus, the SSB/DSB ratio shifts toward the DSB with increasing LET (Christensen et al. 1972) resulting in a low SSB/DSB ratio for high-LET radiation. Therefore, the low SSB/DSB ratio of I-125-UdR shown here experimentally, lead to the conclusion that DNA-incorporated Iodine-125 is an efficient inducer of DSB and, hence, showing rather high-LET type DNA damage pattern with respect to the SSB/DSB ratio. These high-LET type biological effects of the AEE Iodine-125 are compatible with its physical properties. The emission of Auger electrons is, therefore, accordingly regarded as high-LET radiation (Kassis and Adelstein 2005; Balagurumoorthy et al. 2008; Boyd et al. 2008) as low energy short-ranged Auger Electrons deposit a large amount of energy in a very small volume around the decay site.
Comparison of Image-Guided Iodine-125 Seed Interstitial Brachytherapy and Local Chemotherapy Perfusion in Treatment of Advanced Pancreatic Cancer
Published in Journal of Investigative Surgery, 2022
Li Zhou, Hui Yang, Linjun Xie, Jiantong Sun, Jun Qian, Lifei Zhu
For image-guided iodine-125 seed interstitial brachytherapy, a 16-row spiral CT scanner and pinpoint puncture guidance system (Siemens, Germany) was used. The iodine-125 was provided by Ningbo Junan Pharmaceutical Technology Co., Ltd (China), with half-life T1/2 = 59.6 d, photon energy 27.4–35.5 kev, tissue penetration distance 1.7 cm, initial dose rate 7 cGy/h, and the clinical particle activity 0.50–0.90 mci. The radioactive particle therapy planning system (TPS) was provided by Beijing Feitian Zhaoye Technology Development Co., Ltd (China). The Handle implant equipment and Mick gun were obtained from Zhejiang Ningbo Junan Group Inc (China). The number of implanted particles was calculated by TPS as median number 39 (20–60) and the position and direction of the implantation guide needle were also analyzed by TPS according to the CT results. After local anesthesia by 2% lidocaine hydrochloride, the guide needle was introduced into the tumor with no blood or pancreatic liquid by back suction and the position was confirmed by CT scan. Then the iodine-125 particles were implanted with spacing 1.0–1.5 cm. The matched peripheral dose of tumor was 31.1–130 Gy. CT scan was performed to see the distribution of iodine-125 particles. After treatment, the patients were asked to stay in bed for 6 h and were given routine preventive hemostatics and antibiotics for 2 days. All physicians and nursing personnel should take anti-radiation measures for at least 4 months.
Ruthenium plaque radiotherapy in the current era of retinoblastoma treatment
Published in Ophthalmic Genetics, 2022
Guy S. Negretti, Hibba Quhill, Catriona Duncan, Tanzina Chowdhury, Ian Stoker, M. Ashwin Reddy, Mandeep S. Sagoo
Ocular brachytherapy, using radon seeds, was first used to treat retinoblastoma in the 1930s (1). Now, in Europe, ruthenium-106 is commonly used for plaque radiotherapy. In the United States, iodine-125 is the preferred radioactive source. The radioactive plaque is sutured onto the sclera over the tumor and a dose of 40–45 Gray at a dose rate of 1000 CGy per day is typically prescribed (2). Plaque radiotherapy is generally used to treat smaller solitary tumors (AJCC group cT1 and cT2) that have only very localized seeding that can be incorporated into the radiation field or for ocular salvage for the treatment of residual or recurrent tumors (3,4).