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Brachytherapy Treatment and Quality Assurance
Published in Kwan Hoong Ng, Ngie Min Ung, Robin Hill, Problems and Solutions in Medical Physics, 2023
Kwan Hoong Ng, Ngie Min Ung, Robin Hill
A Geiger counter detects 40 counts per second from a sample of Iodine-131. The half-life of I-131 is 8 days. Using the axes given in Figure 8.1, sketch a curve showing the count rate from the sample of I-131 over a period of 20 days. Show your calculations.
Radiation Protection of Staff and the Public
Published in W. P. M. Mayles, A. E. Nahum, J.-C. Rosenwald, Handbook of Radiotherapy Physics, 2021
Mike Rosenbloom, W. P. M. Mayles
Contamination and exposure-rate monitors (calibrated for each radionuclide, e.g. in terms of the annual limit of intake) must be readily available and used at all stages of the therapy procedure. For example, a thin-end-window Geiger counter is suitable for contamination monitoring of β emitters, and a side-window Geiger counter or scintillation detector is suitable for γ emitters. Suitably mounted and shielded monitors should be available for checking contamination of hands. Although 223Ra is an α emitter, it can be detected because of the associated γ-rays.
Radiation Therapy and Radiation Safety in Medicine
Published in Suzanne Amador Kane, Boris A. Gelman, Introduction to Physics in Modern Medicine, 2020
Suzanne Amador Kane, Boris A. Gelman
One way to place radiation doses in context is to consider the values one encounters in daily life. If you were to take a Geiger counter (a type of portable ionizing radiation detector) and measure radiation levels around your home and workplace, you might be surprised to learn that your environment exposes you to ionizing radiation every day. Table 7.1 lists the dose equivalent received by the average US citizen each year, while Figure 7.1 displays this same information graphically. The average radiation dose per person in the US from all sources, averaged over the entire population, is roughly 6.2 mSv per year. Of that total dose, 49.6% is due to natural sources, and slightly over a third of that is due to radon gas (37%), a radioactive gas present in many homes (Figure 7.1). The remaining half (50.4%) due to human-produced sources primarily results from medical x-rays (36%), nuclear medicine uses (12%), and consumer products containing small amounts of radioactive materials (2%). Less than 1% of the total annual dose per capita is due to occupational exposures, fallout, and nuclear power plants. It is notable that the typical additional dose from a standard medical procedure (diagnostic x-rays and nuclear medicine) is about the same as the environmental radiation levels we are all exposed to every year. This is a noticeable increase from the levels due to medical procedures reported in the previous NCRP Report No. 93, in 1987. The average annual dose from diagnostic x-ray and nuclear medicine procedures increased from 0.53 mSv in the early 1980s to 3.0 mSv in the early 2000s.
Schrödinger’s Cat and the Ethically Untenable Act of Not Looking
Published in The American Journal of Bioethics, 2020
Christian J. Vercler, Naomi Tricot Laventhal
One can even set up quite ridiculous cases. A cat is penned up in a steel chamber, along with the following device (which must be secured against direct interference by the cat): in a Geiger counter, there is a tiny bit of radioactive substance, so small, that perhaps in the course of the hour one of the atoms decays, but also, with equal probability, perhaps none; if it happens, the counter tube discharges and through a relay releases a hammer that shatters a small flask of hydrocyanic acid. If one has left this entire system to itself for an hour, one would say that the cat still lives if meanwhile no atom has decayed. The first atomic decay would have poisoned it. The psi-function of the entire system would express this by having in it the living and dead cat (pardon the expression) mixed or smeared out in equal parts.
The lateral arm device for mammographic breast procedures: overview of its uses, safety, and efficacy
Published in Expert Review of Medical Devices, 2021
Amy Kerger, Brandy Griffith, Mitva Patel, Jeffrey Hawley, Stephen P. Povoski
RSL was the first alternative to be placed on the market [7]. It involves the image-guided placement of a 4.5 mm × 0.8 mm titanium seed containing I-125 radioactive isotope. At the time of surgery, the seed can be identified by its emitted radioactivity with a Geiger counter in the operating room. I-125 has a 60 day half-life allowing it to be placed prior to surgery uncoupling the radiology and the surgery schedules. Radioactice seeds can be placed only under mammographic or sonographic guidance. RSL requires significant regulatory oversight with cumbersome radiation safety measures involving radiology, surgery, and pathology departments.
Sentinel lymph node biopsy based on anatomical landmarks and locoregional mapping of inguinofemoral sentinel lymph nodes in women with vulval cancer: an operative technique
Published in Journal of Obstetrics and Gynaecology, 2023
Fong Lien Kwong, Miski Scerif, Jason KW Yap
The authors acknowledge that one of the limitations of this study is that it was conducted in a single cancer centre. Furthermore, the Surgeons relied on radio localisation of the SLN through recognition of the characteristic sound associated with the Geiger counters in all subjects. The fluorescent dye indocyanine green (ICG) has emerged as one of the main tracers for SLN mapping in early gynaecological cancers (Uccella et al. 2022, Raffone et al. 2022). Further randomised controlled trials are required to validate the safety and effectiveness of ICG for real-time intraoperative SLN mapping in vulval cancer.