The iridium 192 It is one of the radioactive isotopes of the metal iridium, with atomic number 77, belonging to group 9, period 6, and group d of the periodic table of elements. This metal has 42 radioactive isotopes, iridium 192 (192Go) one of the most prominent.
The 192Ir has 77 protons and 115 neutrons in its nucleus (which add up to an atomic mass of 192 u). It emits a beta particle (β-) and a gamma radiation (γ).
95.13% of the time, the 192Ir disintegrates by emitting β- to platinum 192 (192Pt); and the remaining 4.87% is transformed into osmium 192 (192Os) by capturing electrons.
By emitting a particle β-, a radioactive isotope undergoes the transformation of a neutron into a proton, thus increasing its atomic number by one unit. As a consequence of this, the 192Go go to 192Pt; since platinum has an atomic number of 78.
The 192Ir is the main isotope used in the treatment of cancer using the brachytherapy technique. Therefore, in this technique, the radioactive emitter is placed in the vicinity of the tumor..
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Silver shiny solid metal. Presents iridescence, which gave rise to its name.
2446 ºC
4428 ºC
22.562 g / cm3. Together with osmium, it is the metal with the highest density.
26.1 kJ / mol.
1.47 Pa at 2716 K
19.7 x 10 m-1.Ω-1
604 kJ / mol.
2.2.
It is resistant to corrosion, including aqua regia.
191.962 g / mol.
77 protons and 115 neutrons.
73,826 days.
106.51 days
Β particle- and radiation type (γ).
Average radiation energy 0.38 MeV, with a maximum energy of 1.06 MeV.
The 192Ir is produced in a nuclear reactor by bombarding the metal iridium with neutrons. This technique avoids the production of unwanted isotopes.
-It is mainly used in so-called non-destructive testing (NOD). It is also used as a radio marker in the oil industry, especially in petrochemical plants and pipelines..
-Industrial gamma radiography is used to examine welds, to test and classify their condition in pressurized pipes, pressure vessels, high capacity storage containers and certain structural welds.
-Industrial gamma radiography has also been used in the examination of concrete, also being used to locate reinforcing bars, conduits inside the concrete. Likewise, this method allows detecting faults in castings..
-The 192Go to examine machined parts and metal plates, and in determining structural abnormalities due to corrosion or mechanical damage.
For industrial use, the 192Ir is placed in sealed containers that emit a beam of gamma radiation that can be oriented. These radiation sources are contained within a welded stainless steel structure that contains a number of isotope discs..
The cameras used in these studies are remote controlled. In this case, the gamma radiation source is moved out of the shielded container to an exposure position. This operation is commonly controlled by a Bowden cable..
The 192Go is one of the main isotopes used in brachytherapy. The technique consists of placing the radioactive isotope in the vicinity of the cancerous tumor for its destruction.
When used in brachytherapy, it is usually used in the form of wires, being used in interstitial implants of 192Go low dose radiation (LDR). The radioactive activity of the wire ranges from 0.5 to 10 mCi per cm. Wire is not a sealed radiation source.
They are also used for high doses of radiation, in the form of tablets placed inside sealed capsules of an alloy of iridium and platinum 3.5 mm in length.
The 192Ir was used in the treatment of 56 patients, between January 1992 and January 1995, by the brachytherapy technique with a high activity of radioactivity, given temporarily in patients with astrocytoma and gliobastoma..
The median survival was 28 months, concluding the authors of the work of this investigation that brachytherapy can improve the control of local tumors and also prolong survival when used in deep malignant brain gliomas.
Of the 40 patients treated with brachytherapy, using 192Ir, 70% of the patients showed no evidence of the disease at the end of the follow-up period.
A high-dose iridium-192 protocol and a follow-up of up to 130 months is used in patients with prostate carcinoma. Using local anesthesia, five or seven hollow needles carrying the isotope are placed into the prostate, by perineal puncture..
Then, a radiation dose of 9 Gy is initially applied to the prostate and the protocol that includes radiation from outside the body is continued..
The International Atomic Energy Agency placed the isotope 192Go in Category 2 of radioactive substances. This indicates that it can permanently harm people who handle radioactive material for minutes or hours, and can even cause death within a few days..
External exposure can cause burns, acute radiation sickness, and even death. Accidental ingestion of the seeds or granules of 192Going can cause burns in the stomach and also in the intestines.
Long-term effects are dependent on the radiation dose, as well as the length of time the radioactive isotope remains in the body..
In the bibliography, several cases of contamination of people with iridium-192 appear, among others.
For example, in 1999, in the Peruvian town of Yenardo, a worker extracted a radioactive source; opened the protection device and placed it in the back pocket of his pants.
Soon after, an erythema appeared at the irradiation site, followed by ulceration, bone necrosis, and finally the man died of septic shock..
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