Radiation in Medicine A Need for Regulatory Reform (1996) / Chapter Skim
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2 Clinical Applications of Ionizing Radiation
2 Clinical Applications of Ionizing Radiation
Pages 39-76
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From page 39... ...
These two categories are further divided by whether the ionizing radiation is administered through external or internal sources. Also of importance for understanding this area of medicine are the many different medical conditions for which these clinical applications are critical and the levels of exposure to radiation involved in each procedure.
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From page 42... ...
Collective dose equivalent is of interest in terms of broad population exposure to radiation overall and to radiation from various medical uses. If medical uses produced a very high exposure compared to the exposure levels encountered in ordinary daily activities, policymakers and others might have reason to direct relatively more attention to the regulation of medical uses of ionizing radiation.
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From page 43... ...
The discussion of each of these two classes of applications addresses types of procedures, utilization, radiation doses, and radiation regulation and control. External Sources: Radiology Types of Procedures In the 100 years since the discovery of x-rays, diagnostic radiology has grown from a scientific curiosity to a pervasive and essential part of modern health care.
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From page 44... ...
These radiographic imaging procedures are in turn typically divided into what are considered"conventional" examinations, on the one hand, and "contrast studies," on the other. Conversational exam rations.
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From page 45... ...
. The frequency of contrast studies decreased from 1970 to 1980, as competing techniques (e.g., endoscopy and colonoscopy for alimentary tract evaluation, ultrasound and Cl for body evaluation, and Cl for central nervous system evaluation)
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From page 46... ...
Utilization Rates The most recent detailed data about the rates of use of radiological diagnostic procedures date to work by the National Council of Radiation Protection (NCRP)
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From page 47... ...
, and the remaining 15 to 20 percent were done in physician offices or outpatient imaging centers. By 1990, approximately 25 to 35 percent of all imaging procedures were estimated to occur outside of hospitals (Sunshine et al., 1991~.
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From page 48... ...
Data in Table 2.4 indicate that the total number of procedures more than doubled, from 136 million to 294 million, between 1970 and 1990, resulting in rates per 1,000 persons of 670 and 1,180, respectively. While the total utilization rate of all imaging procedures per 1,000 population grew 48 percent from 1980 to 1990, rates of procedures that expose patients to ionizing radiation rose only about 28 percent.
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From page 49... ...
Patient-specific radiation dose. Table 2.5 provides, for several common imaging procedures, comparative information related to some of these factors: the average ESK per image, the average EDE per procedure (which can include multiple images)
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From page 50... ...
The NCRP developed an estimate of collective dose equivalent for x-ray procedures in 1980, the last year sufficient data were available for accurate calculation (Edwards, 1995~. In that year, the total collective effective dose to the U.S.
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From page 51... ...
No precise collective dose estimates have been published for 1990. If one assumed that EDE per procedure and the relative frequencies of procedures performed did not change, then collective dose equivalent would track utilization directly.
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From page 52... ...
to control patient exposure through legally imposed patient dose limits, control of professional standards, qualifications, and training does have a direct impact on patient dose. Manufacture and installation of medical x-ray equipment are regulated by the FDA, through 21 CER Part 1020.
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From page 53... ...
This lower resolution of nuclear medicine images is not a major drawback, however, because the clinical utility of nuclear medicine imaging stems primarily from its ability to assess physiologic function rather than anatomy. That is, clinicians pay particular attention to detection and measurement of abnormal organ function rather than to altered organ structure.
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From page 54... ...
, and whether to ready a patient's family for the onset of Alzheimer's disease. Current trends in clinical nuclear medicine include an emphasis on radioimmunodiagnosis, single photon emission computed tomography (SPECI)
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From page 55... ...
As can be seen, in 1993, the total number of procedures exceeded 8 million. In the 20-year period, the number of bone imaging procedures increased dramatically, as did those on the cardiovascular system; conversely, brain imaging procedures dropped.
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From page 57... ...
The NCRP has estimated collective dose to the U.S. population from diagnostic nuclear medicine procedures using the same approach discussed earlier for diagnostic radiology (average EDE per procedure times total number of procedures)
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From page 58... ...
. 58 TABLE 2.9 Selected Reactor-Produced Radionuclides and Their Biomedical Applications Radionuclides Uses RADIA TION IN MEDICINE Arsenic-77 In cancer therapy Bromine-82 In metabolic studies and studies of estrogen receptor content Calcium-47 In studies of cell function and bone fo'~.ation of mammals and to produce scandium-47 Californium-252 In brachytherapy for treatment of cervical cancer and potentially for treatment of gliomas Carbon-14 For medical research to trace metabolism of new drugs and other organic carbon-containing molecules Cerium-141 For research and development on lung densities Cesium-137 To treat cancer; to measure correct patient dosages of radiopharmaceuticals Chromium-51 To assess red blood cell survival studies Cobalt-58 To diagnose pernicious anemia Cobalt-60 To treat cancer and sterilize surgical instruments Copper-64 As a clinical diagnostic agent for cancer and metabolic disorders Copper-67 In cancer therapy and to label antibodies for cancer therapy Dysprosium-165 To treat rheumatoid arthritis Dysprosium-166 Decays to holmium-166, which is used in cancer therapy Einsteinium-253 To radiolabel antibodies for cancer therapy Erbium-169 To treat rheumatoid arthritis Fermium-255 To radiolabel antibodies for cancer therapy Gadolinium-159 In cancer therapy Gold-198 In cancer therapy and to treat rheumatoid arthritis Holmium-166 In cancer therapy and to treat rheumatoid arthritis Iodine-125 As a potential cancer therapeutic agent and for basic biomedical research Iodine-129 To check radioactivity counters in in vitro diagnostic testing Iodine-131 To diagnose and treat thyroid disorders including cancer and for basic biomedical research Iridium-191 To assess cardiac function especially in the pediatric population Iridium-192 In cancer therapy Lutetium-177m In cancer therapy and to label antibodies for cancer therapy Molybdenum-99 To produce technetium-99m, the most commonly used radioisotope in clinical nuclear medicine Osmium-191 Decays to iridium-19lm, which is used for cardiac studies
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From page 59... ...
CLINICAL APPLICATIONS OF IONiZlNG RADIATION Osmium-194 Decays to iridium-194, which is used in cancer therapy Palladium-103 In the treatment of prostate cancer Phosphorus-32 In cancer treatment, cell metabolism and kinetics, molecular biology, genetics research, biochemistry, microbiology, enzymology, and as a starter to make many basic chemicals and research products Phosphorus-33 In cancer treatment, molecular biology and genetic research, and biochemical and enzymological studies Platinum-19Sm In pharmacokinetic studies of antitumor agents Rhenium-186 As a bone cancer therapeutic agent and to radiolabel various molecules as cancer therapeutic agents; also used to treat rheumatoid arthritis Rhenium-188 For treatment of medullary thyroid carcinoma and alleviation of pain in bone metastases Samarium-145 For treatment of ocular cancer Samarium-153 To radiolabel various molecules as cancer therapeutic agents and to alleviate bone cancer pain Scandium-47 In the therapy of cancer Selenium-75 In protein studies in life science research Silver-111 In cancer therapy Strontium-85 To study bone formation and metabolism Strontium-89 To alleviate metastatic bone pain Strontium-90 Decays to yttrium-90, which is used in cancer therapy Sulfur-35 In studies of cell metabolism and kinetics, molecular biology, genetics research, biochemistry, microbiology, enzymology, and as a starter to make many basic chemicals and research products Technetium-99m The most widely used radiopharmaceutical in nuclear medicine imaging Tellurium-123m For research and development on lung densities and calibrating; also used in cardiology Tin-117m For palliative treatment of bone cancer pain Tritium (hydrogen-3) To make tritiated water, which is used as a starter for thousands of different research products and basic chemicals, and for life science and drug metabolism studies to ensure the safety of potential new drugs Tungsten-188 Decays to rhenium-188 for treatment of cancer and rheumatoid arthritis Xenon-133 In nuclear medicine for lung ventilation and perfusion studies Yttnum-90 To radiolabel various molecules as cancer therapeutic agents 59 SOURCE: Adelstein and Manning, 1995, Table 3.1, pages 3~39; reprinted with permission.
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From page 60... ...
60 = 2.10 Sclected ~coler~or-Produced Radionuchdes and Weir Biomedical ~plic~ions ~1~ Ups En-74 ~ ~shmn-eml~ng cbemic~ anyone of pbospboms Badum-128 Pamn1 in ~nemlor system for p~duc1ng Be ~si~n~m1~g ^l~a~ IDS Is Blsmulb-205 Bismulb blolo~c~ di~dbudon Blsmuth-206 Bismuth biolo~c~ disldbulion Bmmine-77 Radioimmunotbempy Bmmine- ~Radioimmunotber~y Cadm1um-109 ~ =~yze meld Ways far cbe~ng sank sump Bang Cedum-139 G~ma-my c~ibm1~n sour ~b~1~7 Cdibmbon of imaging in~men~ Cop~r-61 Poshmn emitter far studies requidog longer time periods Cop~r-64 Poshmn emitter far smd1es Squids longer time Moods; rad10immunolbempy Cop~67 Rad10immunotbempy Ge~1um-68 Parent in the ~nemlor system far producing 1be poshmn emi~ng gaDium-68; ~qui~d in cd1bel~g P~ lomo ~phs, polenlial aDUbody la~1 ~um-lll Radioimmuno~empy Iodine-123 SPE~ bmindm~ing a~nl Iodine-124 Radioimmunolhempy; ~dlmn emi~r ~n-32 ~n 1mce[, ~sitmn emiMer ~33 X-my Ouoms~n~ ~u~ ~a~esium-28 ~a~esium ~car ~emu~-193m Parent in 1be ~nemlor sys~m ~r producing ~ld-193m wbicb is u~d in cardiac blood pool smdies Ru~enium-97 "op~obiDa~ ~ncdon; mmor ~d inO~m~ion 10~11zadon Sc~dium-47 Radioimmunolber~y Sl~nlium-82 Parenl in ~nemlor sys~m ~r producing 1be ~sh~n-emiMing mbidium-82, a ~l=~um analogua T~l~um-179 (my Ouoms~n~ ~ume (sub~imle ~r ~e ~pha~miner ~ld-241 ~bicb is u~d in ca~iac smdies) ~m-201 Ca~i~ im~ng a~nl Tungs~n-178 Parenl in ~nemlor sys~m ~r p~ducing l~l~um-178, sboM Oved =~ning a~nl Vanadium-48 Nu181ion ~d envimomenu1 smdies ~non-122 Paren1 in ~nem~r sys~m ~r producing 1be ~1mn-emiMing iodine-122 Xenon-127 O~d in lung vendladon smdies YMMum-88 Ra~o1mmuno~er~y
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From page 61... ...
Hence most nuclear medicine procedures are performed in Agreement States, under the direction of state regulations. Because state regulations cannot be weaker than federal regulations, the regulation of nuclear medicine is essentially determined by 10 CFR Parts 20 and 35.
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From page 62... ...
External Sources: Radiation Oncology and Teletherapy General Approaches Radiation oncology is the specialty of medicine that deals with treating cancer patients with ionizing radiation. It employs teletherapy, which is radiation
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From page 63... ...
Radiation is indicated to alleviate pain from metastases to bone, to control bleeding or obstruction caused by tumor growth, and to control neurological symptoms due to brain or spinal metastases. As stated above, teletherapy is radiation therapy delivered using an external beam of ionizing radiation.
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From page 64... ...
For more advanced breast cancer, radiation therapy also is used to irradiate the chest wall after mastectomy to reduce the rate of local recurrence. Prostate cancer.
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From page 65... ...
Shown in Table 2.11 is the estimated number of new cases of cancer by site for 1995, together with a rough approximation of the number of those cases that may receive radiation therapy. In addition, by giving the percentage represented by each site of the total number of new cases treated with radiation, Table 2.11 shows which cancer sites are more commonly treated with radiation.
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From page 66... ...
of No. Treated % of Total Treated SiteNew Cases with Radiationa with Radiation Oral cavity Lip 2,550800 0.2 Tongue 5,5501,700 0.3 Mouth 11,0003,300 0.6 Pharynx 9,1002,700 0.5 Digestive organs Esophagus 12,1006,000 1.2 Stomach 22,8000 0 Small intestine 4,6000 0 Large intestine 100,00010,000 1.9 Rectum 38,20019,100 3.7 Liver and biliary 18,500900 0.2 Pancreas 24,00019,200 3.7 Other digestive 2,800300 0.1 Respiratory system Larynx 11,6004,000 0.8 Lung 169,900136,000 26.4 Other respiratory 4,8002,400 0.5 Bone 2,070200 <0.1 Connective tissue 6,0001,800 0.4 Melanoma of skin 34,1003,400 0.7 Breast 183,400128,400 24.9 Genital organs Cervix uteri 15,8004,700 0.9 Corpus uteri 32,80024,600 4.8 Ovary 26,6002,700 0.5 Other, female 5,7002,900 0.6 Prostate 244,00073,200 14.2 Testis 7,1002,100 0.4 Other, male 1,100300 0.1 Urinary organs 79,30011,900 2.3 Eye 1,870200 <0.1 Brain or central nervous system 17,20014,600 2.8 Endocrine glands 15,3801,500 0.3 Leukemia 25,700300 0.1 Other blood or lymph Hodgkin's disease 7,8003,900 0.8
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From page 67... ...
The relatively small number of centers and physicians involved in the specialty of radiation oncology (and the field's exclusive focus on cancer) facilitate in-depth surveys of the patterns of care in clinical radiation therapy.
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From page 68... ...
Not only survival is at issue; radiation therapy of prostate cancer maintains potency in patients at the same rate as state-of-the-art nerve-sparing prostatectomy.
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From page 69... ...
Of course, some chemotherapeutic agents also increase the risk of later malignancy, so choices among therapeutic options are often difficult. Radiation Regulation and Control Regulation and control of external beam radiation therapy is analogous to that of diagnostic radiology and nuclear medicine.
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From page 70... ...
Because linear accelerators and radiation therapy treatment planning systems are Class III medical devices, their safety and manufacture is controlled by the FDA. Problems with the operation of such equipment, particularly those resulting in an adverse patient outcome, must be reported subject to the Safe Medical Device Act, as amended in 1991.
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From page 71... ...
For radiation safety and radiobiological considerations, permanent implants are feasible only with nuclides having a fairly short half-life. In the early days of brachytherapy, radium-226 (Ra-226)
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From page 72... ...
Types of Procedures Brachytherapy is used alone or in conjunction with external beam radiation therapy to treat a wide variety of malignant neoplasms. Perhaps the most prevalent is the use of LDR and HDR intracavitary brachytherapy for treatment of gynecological malignancies.
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From page 73... ...
This document integrates statutory requirements of the NRC and FDA with standards and recommendations from international and national organizations such as the ACR, NCRP, American Association of Physicists in Medicine, American National Standards Institute, International Atomic Energy Agency, and National Institute of Standards and Technology. Internal Unsealed Sources: Therapeutic Nuclear Medicine Overview In contrast to the smaller amount of radioactivity utilized in diagnostic nuclear medicine, larger amounts of radioactivity are intentionally chosen for use in therapeutic nuclear medicine.
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From page 74... ...
Radioimmunotherapy of solid tumors is more problematic, both in terms of getting sufficient dose to the tumor and in accurately calculating tumor dose. Other nuclides are less frequently used to treat a wide range of conditions.
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From page 75... ...
Personnel working with large quantities of I-131 sodium chloride are closely monitored for exposure and thyroid uptake. CHAPTER SUMMARY Diagnostic and therapeutic clinical applications of ionizing radiation range from the simplicity of taking a chest x-ray to the complexity of treating a brain tumor.
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From page 76... ...
Tabar, L., Fagerberg, G., Chen, H-H., Duffy, S.W., Smart, C.R., Gad, \, and Smith, R.N Efficacy of Breast Cancer Screening by Age: New Results from the Swedish Two-County Tnal. Cancer 75~10~:2507-2517, 1995.
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