DEDIcaTED PET EquIPmEnT

FIGURE 8. A Chemical Sketch of FDG

Conventional PET imaging centers have been paying close to $2 million for a dedicated scanner for imaging Because of its glucose orientation, FDG competes

and an additional $2 million for a cyclotron and cyclo- with the body’s glucose for entry into the body’s cells to

tron accessories, which are used for the manufacture of become a part of the intracellular metabolism. But unlike

on-site, positron-emitting radioisotopes and the biosyn- glucose, which continues on with the cell’s metabolic

thesis of radiopharmaceuticals, respectively. Dedicated process, FDG does not proceed past the phosphoryla-

scanners (referred to as conventional PET systems) are tion stage; it remains in the cell, where it is detected and

configured in a circular shape in which rings of detectors imaged during the PET procedure.

surround the patient and detect the gamma rays produced During an FDG-PET scan procedure, most cancer

by the annihilation of the positron-electron pair. The cells ingest more glucose-based FDG than normal

price varies on dedicated scanners, depending on whether cells [about 20 times more, some sources say], because

they are of the high-speed or standard-speed variety. cancer cells thrive on a higher rate of metabolism than

Because scanners and cyclotrons have been such high- Because scanners and cyclotrons have been such high-

A word about PET scanner or camera trends. Conventional whole-body cameras are being used to image any part of the body with only relatively small gains in terms of cost/performance tradeoffs. Currently, cameras especially designed for imaging specific organs of the body, such as cameras for imaging breast cancer, are being developed. These cameras are expected to sport large performance gains as a tradeoff for limited body coverage. Another camera trend is that of imaging small animals, typically mice and rats. The impetus for development of these cameras, referred to as MicroPET scanners, has been the reality that experiments using these small animals require much higher resolutions (8 microliters spatial resolution) than the resolutions achieved in human PET scanners (64 microliters spatial resolution). The higher resolutions in MicroPET scanners, which are being achieved by using smaller scintillator crystals and multianode photomultiplier tubes, permit researchers to conduct serial and longitudinal studies with mice and rats as subjects. In these studies, researchers are able to follow a single animal over time as they monitor the effects of interventions on disease progression and outcome. 16,35

As another way of combating the high cost of dedicated PET equipment, some medical centers have been opting for the services of PET radiopharmacies-companies that manufacture and distribute radiopharmaceuticals. Of the PET radiopharmaceuticals, FDG is the best candidate for radiopharmacy distribution because the 110-minute half- life of the radioisotope [Fluorine-18] from it is synthesized, allows time for the radiopharmaceutical to be transported from radiopharmacy to waiting PET imaging destina- tions. In the year 2000, a UCLA technology publication reported that 50% of hospitals in the United States had PET radiopharmacies located within a 100-mile radius and that the number of PET radiopharmacies was steadily increasing. Radiopharmacies are also located throughout Canada, Europe, Asia, and other parts of the world. 17

Yet another way that some resourceful medical centers are combating the high cost of dedicated PET equipment is by opting for mobile rather than fixed PET scan units. Some hospitals become part of a mobile PET-sharing arrangement where they split the leasing of a mobile unit to minimize financial risk while ascertaining the volume of service that will fill the needs of their organization. Other hospitals use mobile scanners in the transition period while they are making plans to install fixed units. Then, there are the organizations whose projected utilization of a PET scanner is moderate at best, making their participation in

a mobile PET-sharing arrangement their only means of offering PET services. In these arrangements, PET scanners are mounted on trailers and transported on a regular schedule from one medical center to another across the state or even across state lines to neighboring states. 36

sETTIng uP a PET sysTEm

Setting up a PET system requires painstaking planning, which typically includes significant renovation, unless plans call for building a new facility. Generally, some- where around 2,000 square feet are required to properly house a complete PET scan unit, but individual differ- ences can substantially change that requirement. Usually,

a PET scan unit will include a procedure room (the room where the PET scan is conducted) that is very similar to a CT scan facility, an equipment control or operator’s room,

a patient waiting room, a patient prep area, and a patient toilet. If radiopharmaceuticals are to be manufactured on site, a cyclotron room is added to the plan. Within the cyclotron room would be radiochemistry/radiopharmacy areas used for the preparation and dispensing of radiopharmaceuticals. Within the radiopharmacy areas would

be the hot cells where the synthesis of the PET radiopharmaceutical would to be completed. Setting up a PET system also requires providing special training and education for the staff. Personnel will usually need to be trained to minimize patient contact time after administration of the radiopharmaceutical, to maximize distances from high radiation sources, and to properly use barriers and shielding. Obtaining training materials [geared for training personnel] has been a chal- lenge for some of the organizations setting up hybrid systems, mainly because of the newness of hybrid systems. More recently, the personnel training material has become more plentiful as the use of the radiopharmaceutical, FDG, has spread.

Details that may warrant special consideration are the checking and amending [if necessary] of the state radioactive material license and implementing the radiation safety precautions particular to PET. Existing barriers and shielding may need updating to assure that the public and personnel are protected from sources of radioactivity. 17,30,36

PET scan rEImBursEmEnT

PET scan reimbursement—has successfully overcome enough of the obstacles, such that PET has undergone

Until recently, the reluctance of third-party payers, an apparent, steady transition-a transition that has cata- such as Medicare, Medicaid, private insurers, and health

pulted it from its long-standing position in a sophisti- maintenance organizations (HMOs), to provide reim-

cated research environment to its coming of age in the bursement for PET scans was an obstacle to the wide-

clinical sector.

spread use of PET. Because PET was considered an investigative or research procedure by many third-party

rEfErEncEs

payers, providers of PET services were forced to go to great lengths and to expend inordinate amounts of time

1. Positron Emission Tomography: An Introduction. GE Medical

to obtain preapprovals for PET services, a number of

Systems. Available at: http://www.gehealthcare.com/euen/

which were not ultimately reimbursed.

patient/nuclear-medicine-and-pet/exam.html#1. Accessed

The financial obstacles have been diminishing since

August 17, 2011.

the mid and late 1990s when the Heath Care Financing

2. Schewe P, Stein B. Sharper, Cheaper PET Scans. American

Administration (HCFA) began to approve insurance

Institute of Physics. May 16, 1996. Available at: http://www.

reimbursement for more and more PET scan indica-

aip.org/enews/physnews/1996/split/pnu271-1.htm. Accessed

tions. 11,37,38 Late in 2000, the HCFA expanded Medicare

August 17, 2011.

reimbursement to include treatment for six cancers: lung,

3. What is PET? University of Texas Houston Science Center.

colorectal, lymphoma, melanoma, head and neck, and

Available at: http://www.uth.tmc.edu/pet/patients/pet-what-is-

esophageal. The coverage in each of these cancers ranges

pet.htm. Accessed August 17, 2011.

from diagnosis and staging to assessment of therapy and

4. Positron Emission Tomography. Available at: http://legacyweb.

recurrence of disease. The HCFA additionally recom-

triumf.ca/welcome/petscan.html. Accessed August 17, 2011.

mended coverage for assessing myocardial viability and

5. Hamamatsu/Queen’s PET Imaging Center - FAQ. The

imaging the relocation of refractory seizures. A positive

Queen’s Medical Center. Available at: http://www.queenspet-

ramification of the expansion of the Medicare reimburse-

center.com/faq.html. Accessed August 17, 2011.

ment guidelines is that private insurers generally follow

6. Molecular PET and CT Imaging Center of Excellence. The them on reimbursement guidelines. 38 University of Texas MD Anderson Cancer Center Website. Available at: http://www.mdanderson.org/education-and-

conclusIon research/research-at-md-anderson/cancer-imaging-network-of-

texas/centers-of-excellence/molecular-pet-and-ct-imaging/index.

PET is an exciting nuclear medicine technique that

html. Accessed August 17, 2011.

enables the evaluation of the chemical and physiological

7. Brice J. Award winners confirm imaging’s essential role in

changes associated with the metabolic processes in the

medical practice. Diagnostic Imaging Online. January 2002.

human body via the use of non-invasive diagnostic imaging

Available at: http://www.diagnosticimaging.com/dinews/0201.

procedures. These imaging procedures are derived from

diawards.di.shtml. Accessed August 17, 2011.

the physics-based activities that occur when a radiophar-

8. Alumni Profile: Dr. Ronald Nutt. The University of Tennessee

maceutical containing a positron-emitting radioisotope is

College of Engineering. Available at: http://www.engr.utk.edu/

injected into a patient’s body. The physics-based activities

tnengr/fall_00/alumprof.htm. Accessed August 17, 2011.

culminate in the manifestation of electromagnetic energy

9. Phelps ME, Cherry SR. The changing design of positron

that is detected and tracked by intricately designed PET

imaging systems. Clin Positron Imaging. 1998;1:31-45.

scanners or cameras. The detection and tracking of the

10. Converting energy to medical progress: 50-year commit-

electromagnetic energy serve as data that are transformed

ment to improved healthcare though nuclear medicine (Vital

by a PET technologist into diagnostic images that are

legacy of BER medical sciences). Available at: http://www.

analyzed and interpreted by a radiologist and presented

doemedicalsciences.org/pubs/sc0033/vital.shtml. Accessed

in report form to the referring physician.

August 17, 2011.

The benefits that have come forth from the mastery

11. Coleman RE, rev. What is PET? About Nuclear Medicine

of the PET technique (early detection and intervention,

Webpage. Society of Nuclear Medicine Website. Available at:

non-invasive procedures, and monitor of treatment effi-

http://interactive.snm.org/index.cfm?PageID=972&RPID=31

cacy—to name a few) were for a time stymied by a number

06. Accessed August 17, 2011.

of obstacles that deterred the widespread use of the pro-

12. Nutt R. Is LSO the future of PET? Eur J Nucl Med Mol

cedure in the clinical sector. These obstacles included the

Imaging. 2002;29:1523-5.

high cost of dedicated PET equipment, the intricacies of

13. Surti S, Karp JS, Kinahan PE. PET instrumentation. Radiol

setting up a PET system, and the battle over insurance

Clin North Am. 2004;42:1003-16.

reimbursement for PET services. Fortunately, resource-

14. PET/CT Patient Information. Alliance Imaging, Inc. Website.

fulness on the part of impassioned thought leaders and

Available at: http://www.alliancehealthcareservices-us.com/

resolute medical centers—working to bring about radio-

?s=positron+emission+tomography. Accessed August 17, 2011.

pharmacies, mobile PET-sharing arrangements, and

Nutt R, Melcher CL. Current and future developments with LSO, a scintillator with excellent characteristics for PET. Revue

de I’ACOMEN. 1999;5:152-5. Available online at: http://www. univ-st-etienne.fr/lbti/acomen/revue/1999/pdf/pdf2/nutt.pdf. Accessed August 17, 2011. Moses WW. Trends in PET imaging. Nucl Instrum Methods Phys Res A. 2001;471:209-14. Hinton W. Planning for PET. Gene Burton and Associates. Available at: http://www.gbainc.com/Bios.aspx?person=hinto n&dept=Medical%20Technology%20Project%20Managers. Accessed August 17, 2011. PET Scan. Aetna InteliHealth Wesite. Available at: http:// www.intelihealth.com/IH/ihtIH/WSIHW000/9339/23828/ what. Accessed August 17, 2011. Wagner HN Jr. A brief history of positron emission tomography. Semin Nucl Med. 1998;28:213-20. Brownell GL. Radiopharmaceutical development for PET imaging. From: A History of Positron Imaging presentation given at Massachusetts General Hospital on October 15, 1999. Manuscript available online at: http://www.petdiagnostik.ch/ PET_History/alb.html. Accessed August 17, 2011. Nutt R. 1999 ICP Distinguished Scientist Award. The history of positron emission tomography. Mol Imaging Biol. 2002;4:11-26. Stephenson, G. Hopkins first in U.S. to get commercial PET/ CT scanner. Johns Hopkins Medical Institutions Office of Communications and Public Affairs. 2001. Available at: http:// www.hopkinsmedicine.org/press/2001/JUNE/010621.htm. Accessed August 17, 2011. Jaroff L. Inventions of the year: a winning combination. Time Magazine. December 4, 2000. Townsend DW. Dual-modality imaging: combining anatomy and function. J Nucl Med. 2008;49:938-55. Townsend DW, Beyer T, Kinahan PE, et al. The SMART scanner: a combined PET/CT tomograph for clinical oncology. IEEE MIC, Toronto, Canada, M5-01, 1998. Available at: http://ieeexplore.ieee.org/Xplore/login.jsp?url=http%3A%2 F%2Fieeexplore.ieee.org%2Fiel5%2F6268%2F16740%2F00 774368.pdf%3Farnumber%3D774368&authDecision=-203. Accessed August 17, 2011. Newport Diagnostic Center. PET/CT Patient Brochure. Available at: http://www.newportdiagnosticcenter.com/ Portals/129/petCTBrochure.pdf. Accessed August 17, 2011. Wilson, J. Whole-Body Medical Scans. Whole-body medical scans will buy you peace of mind--or sleepless nights. Popular Mechanics. July 2002. Ollinger JM, Fessler JA. Positron-emission tomography. Signal Processing Magazine, IEEE. Jan 1997:14,(1):43-55. Sabbatini RME. The PET Scan: A New Window into the Brain. Brain and Mind Magazine website. Available at: http:// www.cerebromente.org.br/n01/pet/pet.htm. Accessed August

17, 2011. Positron Emission Tomography. Radiology Info website. Available at: http://www.radiologyinfo.org/en/info. cfm?pg=pet. Accessed August 17, 2011. Positron Emission Tomography Scanning. Available at: http:// www.ebme.co.uk/arts/pet.htm. Accessed June 19, 2009.

Position Emission Tomography. Saint Barnabus Ambulatory Care Center website. What is PET? Available at http://www. saintbarnabas.com/pet/what/index.html. Accessed August 18, 2011. Sabbatini RME. The Cyclotron and PET. Brain and Mind Magazine website. Available at: http://www.cerebromente.org. br/n01/pet/pet.htm. Accessed August 17, 2011. Medical Sciences Division of the Office of Biological and Environmental Research of the Office of Science of the U.S. Department of Energy. Converting Energy to Medical Progress. April 2001. Booklet available at: http://www.doemedicalsciences.org/pubs/sc0033/DOESC0033sc.pdf. Accessed August 17, 2011. Chatziioannou AF, Cherry SR, Shao YP, et al. Performance Evaluation of microPET: high-resolution lutetium oxyorthosilicate PET scanner for animal Imaging. J. Nucl Med. 1999;40:1164-75. Rice WW and Grice S. PET scanning: wave of the future. ACE Update [Association of Cancer Executives]. January/February 2001;3:5. Middleton ML, Shell EG. Nuclear medicine application in the clinical setting. Imaging studies aid disease staging and man- agement. Postgrad Med. May 2002;111:89-90, 93-6. Smith WJ. Medicare to reimburse for lung cancer PET imaging. J. Nucl Med. 1998;39:22N.

32.

33.

34.

35.

36.

37.

38.

HIsTory anD DEvEloPmEnT of PET

8. The block detector, invented by Ronald Nutt and

PosT TEsT

Mike Casey

a. improved the efficiency of the process of bio- Expires: August 15, 2013 Approved for 3 ARRT Category A Credits

synthesis of radiopharmaceuticals.

b. allowed CT technology to be integrated into

1. What aspect is a common element of PET, MRI

the PET process.

and CT?

c. lowered the cost of the PET scanner.

a. All the modalities use ionizing radiation to

d. improved the image resolution, but dramatically create an image.

increased the cost of the PET scanner.

b. All the modalities produce cross-sectional

The progression of PET from research to clinical

images.

practice can be attributed to which factor(s)?

c. All the modalities use radiopharmaceuticals.

1. Technical advancements

d. All the modalities document metabolic activity.

2. PET’s ability to identify pathophysiology

2. All of the following are examples of radioisotopes

3. Increased insurance reimbursement

with short half-lives EXCEPT

4. The availability of PET radiopharmaceuticals

a. Carbon-11

a. 1 and 2

b. Nitrogen-13

b. 2 and 3

c. Oxygen-15

c. 1 and 4

d. Radon-222

d. 1, 2, 3 and 4

3. Which of the following are features associated

10. In what year were whole-body PET scans with PET?

introduced?

1. radioisotopes with short half-lives

a. 1986

2. strong electro-magnetic fields

b. 1989

3. a positron-emitting decay scheme

c. 1992

4. the gamma camera

d. 1996

a. 1 only

11. In the late 1990s, what type of detector material

b. 1 and 2

replaced the use of BGO in PET scanners?

c. 1, 3, and 4

a. lutetium oxyorthosilicate (LSO)

d. 1, 2, 3, and 4

b. cadmium tungstate

4. In the early 1950s, what two inventions were intro-

c. sodium iodine

duced that contributed to the development of

d. ceramic rare earth

nuclear medicine?

12. Detector materials introduced in the late 1990s

a. magnetic resonance imaging and

had which advantages?

ultrasonography

1. enhanced image sharpness

b. the rectilinear scanner and the gamma camera

2. improved image contrast

c. the nuclear reactor and the spiral CT scanner

3. decreased scan time

d. phototimers and stable radioisotopes with long

4. increased patient throughput half lives

a. 3 only

5. The first medical cyclotron was built at

b. 1 and 2

a. Hammersmith Hospital in London.

c. 3 and 4

b. Memorial Sloan Kettering Institute in New

d. 1, 2, 3, and 4

York.

13. What factor sets PET apart from CT and MRI?

c. The University of Pennsylvania in Philadelphia.

a. PET images are cross-sectional.

d. The University of Michigan in Ann Arbor.

b. PET is based on biological substrates.

6. In the 1970s neuroscientists began to learn the

c. PET is based on the attenuation of an x-ray beam.

importance of measuring brain blood flow and

d. PET will depict the anatomical location of

metabolism from

structures.

a. early CT studies.

14. Why is PET particularly useful in the field of

b. post-mortem dissections.

oncology?

c. studies of functional brain mapping in animals.

a. PET is inexpensive.

d. combination PET/CT systems.

b. PET is universally available and typically does not

7. Who is credited for developing FDG?

require advance scheduling for an appointment.

a. Godfrey Hounsfield

c. PET is able to detect metabolic activity

b. Ernest O. Lawrence allowing the earlier detection of malignancies.

c. Benedict Cassen and Hal Anger

d. Unlike other modalities, PET does not interfere

d. Al Wolf and Joanna Fowler with treatment options such as radiation and chemotherapy.

23. Which statement(s) are TRUE concerning imaging because

15. Before 1995, most insurers did not pay for PET

positrons?

1. the procedure was expensive.

1. Positrons are produced when radioactive sub-

2. the procedure will considered experimental.

stances decay.

3. the procedure was very dangerous.

2. Positrons are subatomic particles that have

a. 2 only nearly all the characteristics of electrons.

b. 3 only

3. Positrons are positively charged

c. 1 and 2

4. Positrons are antimatter that live short, violent

d. 1, 2, and 3

lives.

16. In 2000, the HCFA expanded Medicare to cover

a. 1 only

imaging for which cancers?

b. 1 and 2

a. lung, colorectal, lymphoma, melanoma, head

c. 2 and 3

and neck, and esophageal

d. 1, 2, 3, and 4

b. bone, breast, pancreatic, cervical, and ovarian

24. When electrons collide with positrons, the elec-

c. prostate, bladder, uterine, hepatic, and Kaposi’s

trons and positrons are destroyed and their mass is

sarcoma

transformed into

d. gallbladder, renal, neuroblastoma, testicular and

a. x-ray energy that is the same strength as that chronic myelogenous leukemia

used in CT.

17. What is the half life of FDG?

b. electromagnetic radiation.

a. 20 minutes

c. a pair of high-energy gamma rays.

b. 110 minutes

d. an alpha particle.

c. 7 hours

25. The distance that a positron travels in tissue

d. 16 hours

before annihilation depends on the

18. Which scientists are responsible for the produc-

a. kinetic energy of the positron when it is

tion of the new combination PET/CT scanner?

emitted.

a. Ernest O. Lawrence and Benedict Cassen

b. age of the patient.

b. Gordon Brownell and Hal Anger

c. physical composition of the patient (i.e. degree

c. David Townsend and Ronald Nutt of muscle or fat tissue present).

d. Michel Ter-Pogossian, David Kuhl and

d. method used to create the radiopharmaceutical. William Powers

26. A time frame known as _______ is used to deter-

19. The combination PET/CT scanner is often mine whether two events occurring on opposite referred to as

sides of the patient are actually coincident.

a. a multidetector system.

a. an alpha decay

b. the SMART scanner.

b. a 180-degree pulse

c. SPECT.

c. a coincidence window

d. spiral scanner.

d. a chi-square test

20. The radiopharmaceuticals used for PET

27. The PET scanner collects all coincident events

a. directly emit gamma rays.

and sorts them in the form of lines into a

b. emit positrons that are ultimately converted to

a. histogram.

gamma rays.

b. sinogram.

c. must be produced in onsite cyclotrons.

c. line spread function.

d. emit beta particles.

d. Gaussian probability distribution.

28. A particular radiopharmaceutical is chosen for an processes as

21. PET imaging allows the evaluation of such bodily

individual patient exam based on its

1. glucose metabolism

a. availability.

2. oxygen metabolism

b. affinity for a particular organ or body system.

3. cerebral blood flow

c. cost.

4. bowel peristalsis

d. atomic weight

a. 1 only

29. The detectors in the PET system contain _______

b. 1 and 2

that produce electronic signals when they are

c. 1, 2 and 3

struck by gamma rays.

d. 1, 2, 3 and 4

a. a radioisotope

22. PET uses radiopharmaceuticals that

b. computer chips

a. directly emit gamma rays.

c. scintillation crystals

b. contain positron-emitting radioisotopes.

d. an electron accelerator

c. do not emit any type of radiation.

d. are stable, with very long half-lives.

37. Which radiopharmaceutical is so widely used that image signify

30. Different colors and degrees of brightness in the

its name has become synonymous with the term

a. different levels of body function.

“radiopharmaceutical”?

b. different densities of body tissue.

a. FDG

c. that not enough time has elapsed between injecting

b. Cr-51

the radiopharmaceutical and acquiring images.

c. 11C-CFT

d. an inadequate amount of radiopharmaceutial

d. 13NH3

was injected.

38. Cancerous areas appear as “hot spots” on the PET

31. In the instance of oncologic studies where a glu-

scan because

cose-based radiopharmaceutical is used, healthy

a. cancer cells divide and grow more quickly than

tissue will

normal cells.

a. be undetectable.

b. the normal tissue surrounding the cancer cells

b. show up on the image as background area. have a higher metabolic rate and therefore

c. appear much brighter. attract more of the FDG.

c. cancer cells die more quickly than normal cells. why a glucose-based radiopharmaceutical should

d. be identical to cancerous tissue and is the reason

d. cancer cells contain more oxygen than normal not be used for oncologic studies.

cells.

39. Which of the following has been an obstacle to the after their PET exam?

32. Why are patients urged to drink plenty of liquids

widespread use of PET?

a. To reduce the chance of renal failure

a. It is more invasive than other diagnostic

b. To extend the half-life of the

procedures.

radiopharmaceutical

b. It is not effective for early detection of disease.

c. To dilute the radiopharmaceutical and thereby

c. Dedicated PET equipment is very expensive. reduce its toxicity

d. It is unable to monitor the efficacy of a patient’s

d. To assure elimination of the radiopharmaceu-

treatment.

tical from their systems as quickly as possible

40. A MicroPET scanner is used to

thereby reducing radiation exposure

a. analyze specimens sent to the lab.

33. Which of the following are PET scans modes?

b. image small animals, such as mice.

1. whole-body static

c. image specific organs of the body, such as the

2. active dynamic

breast.

3. gated

d. study a specific metabolic process, such as glu-

4. three-dimensional-volume-imaging

cose metabolism.

a. 1 only

34. Most radiopharmaceuticals used in PET contain which two components?

a. A carrier molecule and a positron-emitting radioisotope

b. Glucose and radioactive iodine

c. A water molecule and a heavy metal molecule

d. An oxygen molecule and a third category radioisotope

35. A machine that accelerates protons and then smashes them into the nuclei of stable or nonra- dioactive elements is called a

a. generator

b. linear accelerator

c. display accelerator

d. cyclotron

36. PET radioisotopes are divided into three catego- ries based on

a. their degree of radioactivity.

b. how and where they are made.

c. the body function that they measure.

d. the length of their half-life.

Brighton, MI 48116-0300

History and development of pet

Phone: 810-229-3354 Fax: 810-229-3235

expires august 15, 2013

E-mail: info@cewebsource.com

DEDIcaTED PET EquIPmEnT