Radioactive Implants

8 Key excerpts on "Radioactive Implants"

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  Radioisotopes

  Applications in Bio-Medical Science

  • Nirmal Singh(Author)
  • 2011(Publication Date)
  • IntechOpen

    (Publisher)

  The third branch is radiation therapy, which is the ultimate aim of all diagnostic investigations. Here the tissues or organs are treated with radiation and restored to the normal functions in the human body (Loveland, et al., 2006). * A. Azzam 1,3 , M. McCleskey 2 , B. Roeder 2 , A. Spiridon 2 , E. Simmons 2 , V.Z. Goldberg 2 , A. Banu 2 , L. Trache 2 and R. E. Tribble 2 1 Faculty of Sciences, Physics Department, Princess Nora University Riyadh, Saudi Arabia, 2 Cyclotron institute, Texas A&M University, College Station, TX, USA 3 Nuclear Physics Department., Nuclear Research Center, AEA, Cairo, Egypt Radioisotopes – Applications in Bio-Medical Science 4 The two fundamental considerations in the administration of radioactivity to the human body are (Krane, 1987):  Efficient detection of the radiation from outside the body,  Radiation dose caused to the patient. Diagnostic techniques in nuclear medicine use radioactive tracers which are easily detectable and which help to investigate various physiological and metabolic functions of the human body. Diagnosis is usually conducted by short-lived radionuclides, generally attached to a suitable chemical compound. Depending on the nature of the radiopharmaceutical, it may be inhaled, ingested, or injected intravenously (St ő cklin, et al., 1995). The radiation emitted by the radionuclide provides different kinds of information, as required for diagnosis. Radionuclides are powerful tools for diagnosis due to three reasons: 1. The mass of the sample is infinitesimally small, as low as 10 -10 g of radioactive material, so it does not disturb the biological equilibrium. 2. The radioactive form of an element behaves exactly the same way as the non-radioactive element. 3. Each radioactive material spontaneously decays into some other form with emission of radiation. This radiation can be detected from outside the body.

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  Practical Radiotherapy

  Physics and Equipment

  • Pam Cherry, Angela M. Duxbury, Pam Cherry, Angela M. Duxbury(Authors)
  • 2019(Publication Date)
  • Wiley-Blackwell

    (Publisher)

  CHAPTER 13 The Use of Radionuclides in Molecular Imaging and Molecular Radiotherapy

  Paul Shepherd OBE and Terri Gilleece

  Aim

  The aim of this chapter is to introduce the fundamental principles and practice of the use of radionuclides in molecular imaging and molecular radiotherapy.

  13.1 Introduction

  Radionuclides play a dual function in the management of cancer. Radionuclide imaging is used for the diagnosis, staging, and monitoring of cancer, and in radiotherapy or brachytherapy radionuclides have been at the forefront of cancer treatment for decades. A good example is the use of radioactive iodine in both the imaging and the treatment of thyroid cancers.

  A therapeutic radiographer is required to have an understanding of the physical principles underpinning and the potential hazards associated with the use of radionuclides in imaging and radiotherapy practice. Radionuclides are localised to the desired tissue by being chemically attached to, or incorporated into, a compound that is designed to follow a known biodistribution in the body. There are a number of different mechanisms by which this is achieved. The radionuclide and compound together is known as the radiopharmaceutical (RP ). By introducing RPs into the body that follow specific physiological pathways whilst emitting radiation, it is possible to detect and map penetrating radiation from outside the body to produce images or to use non‐penetrating radiation for therapy. In therapeutic applications the activities administered are much higher than for imaging. In recent years, methodologies have been developed specifically for tumour imaging (molecular imaging) and the targeting of tumours with radionuclides or molecular radiotherapy (MRT

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  College Physics

  • Paul Peter Urone, Roger Hinrichs(Authors)
  • 2012(Publication Date)
  • Openstax

    (Publisher)

  Radiation detectors external to the body can determine the location and concentration of a radiopharmaceutical to yield medically useful information. For example, certain drugs are concentrated in inflamed regions of the body, and this information can aid diagnosis and treatment as seen in Figure 32.4. Another application utilizes a radiopharmaceutical which the body sends to bone cells, particularly those that are most active, to detect cancerous tumors or healing points. Images can then be produced of such bone scans. Radioisotopes are also used to determine the functioning of body organs, such as blood flow, heart muscle activity, and iodine uptake in the thyroid gland. 1278 Chapter 32 | Medical Applications of Nuclear Physics This OpenStax book is available for free at http://cnx.org/content/col11406/1.9 Figure 32.4 A radiopharmaceutical is used to produce this brain image of a patient with Alzheimer’s disease. Certain features are computer enhanced. (credit: National Institutes of Health) Medical Application Table 32.1 lists certain medical diagnostic uses of radiopharmaceuticals, including isotopes and activities that are typically administered. Many organs can be imaged with a variety of nuclear isotopes replacing a stable element by a radioactive isotope. One common diagnostic employs iodine to image the thyroid, since iodine is concentrated in that organ. The most active thyroid cells, including cancerous cells, concentrate the most iodine and, therefore, emit the most radiation. Conversely, hypothyroidism is indicated by lack of iodine uptake. Note that there is more than one isotope that can be used for several types of scans. Another common nuclear diagnostic is the thallium scan for the cardiovascular system, particularly used to evaluate blockages in the coronary arteries and examine heart activity. The salt TlCl can be used, because it acts like NaCl and follows the blood.

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  Essentials of Inorganic Chemistry

  For Students of Pharmacy, Pharmaceutical Sciences and Medicinal Chemistry

  • Katja A. Strohfeldt(Author)
  • 2014(Publication Date)
  • Wiley

    (Publisher)

  This is not as simple as it sounds, as radioactive material undergoes continuous decay. Therefore, it is important to state when the activ- ity was measured and what the half-life of this radionuclide is. Radiopharmaceuticals are typically dispensed in doses of units of activity (mainly kilobecquerel or megabecquerel). 10.3 Therapeutic use of radiopharmaceuticals Radiopharmaceuticals that are used therapeutically are molecules with radiolabelling. This means that certain atoms in this molecule have been exchanged by their radioactive isotopes. These radiolabelled molecules are designed to deliver therapeutic doses of ionising radiation (mostly β-radiation) to specific disease sites around the body. The more specific the targeting is, the fewer the side effects expected. For any design of a treatment regime including radiopharmaceuticals, it is important to consider what the decay properties of the radionuclide are and what the clearance route and rate from nontarget radiosensitive tissue is. 10.3.1 131 Iodine: therapy for hyperthyroidism Iodine has the chemical symbol I and atomic number 53. It is a member of the halogens (group 17 of the periodic table of elements) (Figure 10.13). Elemental iodine is characterised by the purple colour of its vapour. Free iodine typically exists (like the other halogens) as the diatomic molecule I 2 . Iodide (I − ) is the highly water-soluble anion, which is mainly found in the oceans. Iodine and its compounds are mainly used in nutrition. It has relatively low toxicity and is easy to include into organic compounds, which has led to its application as part of many X-ray contrast agents. Iodine is required by humans to synthesise the thyroid hormones, and therefore iodine will accumulate in the thyroid gland. Iodine has only one stable isotope ( 127 53 I), but it has several radioactive isotopes. Some of these are used for medicinal purposes including diagnostic tests and treatment.

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  Advances in Biological and Medical Physics

  Volume 1

  • John H. Lawrence, Joseph G. Hamilton, John H. Lawrence, Joseph G. Hamilton(Authors)
  • 2013(Publication Date)
  • Academic Press

    (Publisher)

  If radiation is ever to prove a vital tool for the palliation or cure of malignancy, the only possible way to accomplish this end would seem, from our present per-spective, to be the discovery of organic substances which undergo highly selective localization in various types of cancer cells in contrast to those of normal tissue, and which can be labeled with a suitable radioisotope. Tritium with the low penetrating power of its beta-rays and its rapid turnover in the body is particularly interesting in this regard. If it can be put in relatively stable positions in localizing compounds, it will expend most of its ionizing power within the concentrating cells. Potentially it is an ideal radiotherapeutic agent. A discussion of radiotherapy with isotopes would not be complete without mention of fissionable isotopes—i.e., of uranimn— 92^^ —and plutonium— 94Pu ^39 —a ^j^d Qf other isotopes that release large amounts of ionizing radia-tion upon being bombarded with slow neutrons—i.e., of lithium— 3LÍ®—and boron—gB^^ If these materials can be locaUzed in given tissues and organs and the region bombarded with S I OAV neutrons, a significantly higher radi-ation can be conferred on the isotope-containing tissue than on the normal or involved tissue through Avhich the neutrons also must pass. Ej-uger (1940) has shown that pieces of transplantable mouse tumor soaked in boric acid solution and then irradiated in vitro with slow neutrons before inoculation into new hosts showed a significantly lower percentage of takes than control tumor pieces soaked in boric acid, but not irradiated. Zahl, Cooper and Dunning (1940) have shown that, if lithium or boron salts are infiltrated into mouse tumors in vivo and the host animals bombarded with slow neu-trons, there is a significant increase in tumor regression over that in bom-barded, but uninjected controls.

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  Handbook of Radiobiology

  • Kedar N. Prasad(Author)
  • 2020(Publication Date)
  • CRC Press

    (Publisher)

  Chapter 24

  RADIOISOTOPES IN BIOLOGY AND MEDICINE

  CONTENTS

  I. Introduction

  II. General Princinles

  A. Physical Properties

  B. Safe Handling and Disposal

  C. Assaying Techniques

  III. Radioisotopes in Biological Research

  A. Techniques

  IV. Neutron Activation Analysis

  V. 131 I in Thyroid Physiology

  VI. Hematologic Studies

  VII. Renal Function Study

  A. Radiotracers for the Brain

  VIII. Liver Function Study

  A. Tumor Imaging

  B. Cardiovascular Function Study

  C. Positron Emission Tomography (PEl)

  IX. Treatment of Diseases

  A. Hyperthyroidism

  B. Thyroid Cancer

  C. Treatment of Polycythemia and Blood Neoplasms

  X. Summary and Comments

  References

  I. INTRODUCTION

  Although the potential value of radioisotopes in biological and medical research was realized soon after their discovery, their usage remained very limited. This was due to the fact that the production of different types of radioisotopes was not technically possible. A major breakthrough in the production of radioactive materials came after the invention of the cyclotron by Lawrence of the University of California at Berkeley. Later, during World War II, Fermi and associates at the University of Chicago succeeded in achieving a chain reaction with 235 U, which allowed the construction of a nuclear reactor. Today, most of the radioisotopes of biological and medical interest are produced either by a cyclotron or by a nuclear reactor. At present, radioisotopes are widely used in biological and medical research. The main references are listed at the end of this chapter.

  1 , 2 , 3 , 4 , 5 , 6 , 7

  II. GENERAL PRINCIPLES

  To use radioisotopes most effectively and safely, one must know the following:

  1.  Physical properties of radioisotopes 2.  Procedures of safe handling and safe disposal 3.  Techniques of assaying radioactivity

  A. PHYSICAL PROPERTIES

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  Essentials of Nuclear Medicine Physics, Instrumentation, and Radiation Biology

  • Rachel A. Powsner, Matthew R. Palmer, Edward R. Powsner(Authors)
  • 2021(Publication Date)
  • Wiley-Blackwell

    (Publisher)

  239 Essentials of Nuclear Medicine Physics, Instrumentation, and Radiation Biology , Fourth Edition. Rachel A. Powsner, Matthew R. Palmer, and Edward R. Powsner. © 2022 John Wiley & Sons Ltd. Published 2022 by John Wiley & Sons Ltd. CHAPTER 18 This chapter is divided into two parts. The first part is a review of several common therapeutic radiophar‑ maceuticals and their biological mechanism of uptake. The second part reviews radiation protection practices for handling and administering these radiopharmaceuticals. Introduction Radiopharmaceuticals are compounds composed of biologically active radioisotopes bound to another ion, or radioisotopes bound by a linker molecule to a carrier molecule that has high affin‑ ity for a special target or function in an organ or tissue (Figure 18.1). If the radioisotope emits gamma rays, X‐rays, or positrons it is diagnostic; if it emits alpha or beta par‑ ticles it is therapeutic. Some radiopharmaceuticals can be both diagnostic and therapeutic. Paired diagnostic and therapeutic radiopharmaceuticals Most therapeutic radiopharmaceuticals are “paired” with a diagnostic radiopharmaceutical. This diag‑ nostic agent is used to characterize the target tissue or organ, predict the uptake and estimate the dosim‑ etry of its therapeutic counterpart prior to treatment. Several therapeutic and diagnostic radiopharma‑ ceuticals pairs are not structurally identical, but have similar or identical biologic uptake in an organ. Examples are 223 Ra‐dichloride (therapeutic) and 99m Tc‐phosphonate compounds (diagnostic). Another example is 90 Y‐microspheres (therapeutic) and 99m Tc‐ macroaggregated albumin ( 99m Tc‐MAA—diagnostic). When a thera peutic radiopharmaceutical and a diag nostic radiopharmaceutical are identical except for their radioisotopes, they are called theranostic .

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  Handbook of Radiopharmaceuticals

  Methodology and Applications

  • Michael R. Kilbourn, Peter J. H. Scott(Authors)
  • 2021(Publication Date)
  • Wiley

    (Publisher)

  The rapid degradation of a radiopharmaceutical not only decreases its therapeutic efficacy but may result in the formation of radioactive metabolites that can accumulate in off-target tis- sues. For example, many free radiometals tend to accumulate in bone, which can cause increased toxicity to the radiosensitive bone marrow [72, 79, 80]. However, the use of che- lators that form highly stable coordination complexes with radiometals can help prevent the toxicological effects resulting from the release of the radiometal [7]. One limiting factor of endoradiotherapy is the development of radioresistance by cancer cells. Radioresistance is the process by which cancer cells adapt to the biological changes induced by radiating particles, thereby limiting the therapeutic effects of the radiopharmaceutical. Although the exact mechanisms of radioresistance remain unknown, combinational approaches that include radiosensitizers may improve patient outcomes [81]. Furthermore, radioresistance may be combatted by selecting suitable 550 Handbook of Radiopharmaceuticals radionuclides; for example, it has been shown that alpha particles can overcome some of the limitations caused by radioresistance to beta particle therapy [82]. 18.3.3 Applications Since Alexander Graham Bell’s initial suggestion of using radionuclides for the treatment of cancer, a wide variety of radiopharmaceuticals have been developed, some of which have been approved for clinical use by the US FDA and/or the EMA (Table 18.2). The majority of clinically approved radiopharmaceuticals are for the palliative treatment of bone metastases and rely upon the uptake of the calcimimetic radiometals by hydroxy- apatite. Currently, two radiolabeled monoclonal antibodies have been approved for clinical use: [ 131 I]I-tositumomab and [ 90 Y]Y-ibritumomab tiuxetan, both of which target CD22-positive cells in hematological cancers.

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