Sedentary Work Exerting up to 10 pounds (4.5 kg) of force occasionally and/or a negligible amount of force frequently or constantly to lift, carry, push, pull, or otherwise move objects, including the human body. Sedentary work involves sitting most of the time, but may involve walking or standing for brief periods of time. Jobs are sedentary if walking and standing are required only occasionally and other sedentary criteria are met.

Light Work Exerting up to 20 pounds (9.1 kg) of force occasionally and/or up to 10 pounds (4.5 kg) of force frequently, and/or negligible amount of force constantly to move objects. Physical demand requirements are in excess of those for Sedentary Work. Light Work usually requires walking or standing to a significant degree. However, if the use of the arm and/or leg controls requires exertion of forces greater than that for Sedentary Work and the worker sits most the time, the job is rated Light Work.

Medium Work Exerting up to 50 (22.7 kg) pounds of force occasionally, and/or up to 25 pounds (11.3 kg) of force frequently, and/or up to 10 pounds (4.5 kg) of forces constantly to move objects.

Heavy Work Exerting up to 100 pounds (45.4 kg) of force occasionally, and/or up to 50 pounds (22.7 kg) of force frequently, and/or in excess of 20 pounds (9.1 kg) of force constantly to move objects.

Very Heavy Work Exerting in excess of 100 pounds (45.4 kg) of force occasionally, and/or in excess of 50 pounds (22.7 kg) of force frequently, and/or in excess of 20 pounds (9.1 kg) of force constantly to move objects.

Job Classification

In most duration tables, five job classifications are displayed. These job classifications are based on the amount of physical effort required to perform the work. The classifications correspond to the Strength Factor classifications described in the United States Department of Labor's Dictionary of Occupational Titles. The following definitions are quoted directly from that publication.

Sedentary Work Exerting up to 10 pounds (4.5 kg) of force occasionally and/or a negligible amount of force frequently or constantly to lift, carry, push, pull, or otherwise move objects, including the human body. Sedentary work involves sitting most of the time, but may involve walking or standing for brief periods of time. Jobs are sedentary if walking and standing are required only occasionally and other sedentary criteria are met.

Light Work Exerting up to 20 pounds (9.1 kg) of force occasionally and/or up to 10 pounds (4.5 kg) of force frequently, and/or negligible amount of force constantly to move objects. Physical demand requirements are in excess of those for Sedentary Work. Light Work usually requires walking or standing to a significant degree. However, if the use of the arm and/or leg controls requires exertion of forces greater than that for Sedentary Work and the worker sits most the time, the job is rated Light Work.

Medium Work Exerting up to 50 (22.7 kg) pounds of force occasionally, and/or up to 25 pounds (11.3 kg) of force frequently, and/or up to 10 pounds (4.5 kg) of forces constantly to move objects.

Heavy Work Exerting up to 100 pounds (45.4 kg) of force occasionally, and/or up to 50 pounds (22.7 kg) of force frequently, and/or in excess of 20 pounds (9.1 kg) of force constantly to move objects.

Very Heavy Work Exerting in excess of 100 pounds (45.4 kg) of force occasionally, and/or in excess of 50 pounds (22.7 kg) of force frequently, and/or in excess of 20 pounds (9.1 kg) of force constantly to move objects.

Bone Scan


Related Terms

  • Bone Scintigraphy
  • Nuclear Medicine Scan
  • Radionuclide Bone Scan

Specialists

  • Nuclear Medicine Specialist
  • Radiologist

Medical Codes

ICD-9-CM:
92.14 - Bone Scan

Overview

A bone scan is a nuclear scanning/imaging test or diagnostic procedure used to evaluate abnormalities involving bones and joints. The bone scan is actually part of a three-phase nuclear scan. The first phase is vascular, in which a radioactive substance (isotope) is injected intravenously and taken up in the circulation; the second phase is soft tissue, with radioactive uptake in muscles and tendons; and the third phase is bone. The isotope, which poses no health risk, circulates throughout the body and collects preferentially in bone tissue that is growing or is, for some reason, more metabolically active. Such metabolically active sites include areas of inflammation (e.g., cellulitis, showing uptake in phases 1 and 2), injury (fractures, stress fractures), infection, and bone turnover associated with cancer (Wheeless). A scanning device called a gamma camera is passed over the body to detect and record the metabolically active sites that are then imaged by a special computer.

A three-phase/triphasic bone scan is performed where 20 to 30 minutes of images (1st and 2nd phases) are taken during the initial injection. The individual then returns 2 to 3 hours later for additional images (3rd phase). The three-phase bone scan detects different types of pathology in the bone depending on the phase. Phase 1 is also known as the nuclear angiogram or the flow phase, with serial scans taken during the first 2 to 5 seconds after injection.

Phase 2, also known as the blood pool image, is obtained 5 minutes after injection. This phase will show areas with moderate to severe inflammation because of dilated capillaries that result in stagnant blood flow, allowing the radioisotope to "pool."

Phase 3, or the delayed phase, is the traditional bone scan. It is obtained 2 to 3 hours after the injection, when the majority of the radioisotope has been metabolized. This phase best shows the amount of bone turnover associated with the area of concern.

Areas of increased metabolism (activity) appear black and dark and are called "hot spots," whereas areas of decreased metabolism are called "cold spots." Hot spots may indicate healing fractures, tumor, infections, or other processes that trigger higher metabolism such as increased blood flow or new bone formation. Cold spots are indicators of decreased metabolism such as poor blood flow to an area of bone or bone destruction from a tumor. The scan is interpreted to be normal if there are no areas of increased or decreased pooling of the injected material. The normal appearance of the scan will vary according to the individual's age, but in general, a normal scan shows a uniform concentration of the isotope uptake in all bones.

Different isotopes are used to evaluate different problems. Scans are often ordered by the isotope name. For example, a technetium scan is ordered for studying problems with bone injury, a gallium scan for soft tissue and inflammation concerns, an indium scan for possible infection, and a sulfur colloid scan for bone marrow pathology.

The injection of a radioactive isotope is thought to be a safe procedure, as the total dose of radiation absorbed is very small and the radioactive isotope has a short half-life (i.e., it decays rapidly into nonradioactive form); it is almost completely eliminated from the body within 24 hours via the urine. The amount of absorbed radiation is dependent on the type of isotope used, ranging from 1.5 mSv to 5 mSv, well within the cumulative lifetime radiation exposure limit of 100 mSv (Heston).

Source: Medical Disability Advisor



Reason for Procedure

Bone scans are sensitive to the metabolism of a bone area as opposed to x-rays that are sensitive to the bone's structure. Therefore, bone scans can diagnose diseases and conditions not apparent on x-rays, e.g., bone scans can diagnose stress fractures and fractures of the carpal scaphoid in the wrist because they reflect the increased metabolism of areas that are injured or healing, whereas x-rays may not capture the minimal structural damage of such fractures.

Bone scans are frequently ordered to help detect or rule out primary or metastatic bone cancer when x-rays reveal no abnormalities but when malignancy is suspected. Bone scans also identify bone infection (osteomyelitis), determine where the abnormality is before bone biopsy or surgery is performed, and identify other conditions that do not always appear on x-rays.

Bone scans are also ordered to help diagnose early arthritic changes and monitor both the progression of the disease and the effectiveness of treatment, to determine whether artificial joint implants have loosened or are infected, and to evaluate the healing of bone grafts.

Source: Medical Disability Advisor



How Procedure is Performed

A conventional bone scan is performed in a radiology facility, either in a hospital or an outpatient x-ray center. The individual sits in a chair or lies on a table while the radioactive substance is injected through a vein in the arm. There is then a 1 to 3 hour waiting period while the substance collects within the skeletal system. While the patient is waiting, the individual is instructed to drink several glasses of water and to urinate frequently so as to ensure that the radioactive material is not concentrated in the urinary bladder, which could obscure visualization of the pelvic bones during the procedure.

For the scan, the individual lies face up on a table but may be repositioned to the stomach or side during the procedure. It is important that the individual not move during the procedure except when directed by the technologist. The radionuclide scanner, sometimes called a gamma camera, is positioned over the body part to be examined. The camera, table, or both may change position during the study. In a total body bone scan, the individual is scanned from head to foot over a period of 30 to 60 minutes. The individual should experience no discomfort during this procedure.

Variations of the conventional bone scan procedure include the Single Photon Emission Computed Tomography (SPECT) scan and the 3-stage scan. The SPECT scan is added to the conventional bone scan procedure and can study a particular part of the body in more detail. An additional 45 to 60 minutes is added to the procedure by the SPECT scan.

The 3-stage scan is similar to the conventional scan except the scanning takes place during injection, approximately 20 minutes after the radioactive substance is injected, and then again 2 to 4 hours after injection.

Source: Medical Disability Advisor



Complications

The scanning portion of the exam is without risk. However, use of the isotope is not recommended during pregnancy or for nursing mothers to avoid exposing the fetus or infant to radiation; if a nursing mother must have the test, breast milk should be pumped and discarded for 2 days following the test. In individuals with poor kidney function and renal osteodystrophy, the bone may not absorb a sufficient amount of the isotope for a valid bone scan.

Although extremely rare, certain individuals may develop an allergic reaction to the injected radioactive isotope, which may cause a rash, swelling, or anaphylactic shock. These complications are typically short-lived, and are easily treated with medication.

Source: Medical Disability Advisor



Ability to Work (Return to Work Considerations)

Barring side effects from the test or discovery of a condition requiring urgent treatment, individuals are able to return to work or resume previous activities immediately after the scan.

Source: Medical Disability Advisor



Maximum Medical Improvement

1 day.

Source: Medical Disability Advisor



References

Cited

Heston, Thomas F. "Bone Scan." eMedicine. Ed. Gowthaman Gunabushanam. 15 Jul. 2013. Medscape. 2 May 2014 <http://emedicine.medscape.com/article/2109077-overview>.

Wheeless, Clifford R. "Triphasic Bone Scan." Wheelis' Textbook of Orthopaedics. Eds. James A. Nunley and James R. Urbaniak. Duke Orthopaedics, 2012.

General

"Bone Scan." WebMD.com. 1 Oct. 2012. WebMD, LLC. 2 May 2014 <http://www.webmd.com/a-to-z-guides/bone-scan>.

Source: Medical Disability Advisor






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