One Step Closer to Educating the Hybrid Technologist

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Discusses the educational requirements and curriculum for PET/CT imaging.

Author: Taffi Rose, BS, RT(R)
Credits: 1

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The development of hybrid fusion imaging equipment such as PET (Positron Emission Tomography)/CT (Computed Tomography) has led to the need for multi-skilled technologists to operate them. Ideally, PET/CT operators would be dually certified in both CT and Nuclear Medicine, however, few technologists have credentials in both.

This article will review the history and evolution of PET/CT fusion imaging, the recommended curriculum for PET/CT operators, and certification requirements for the newly augmented PET certification examination for 2005. It will also explore the need for ongoing improvements in training, and ultimately the development of formal educational programs for multi-skilled technologists.


Since the introduction of the first hybrid equipment to the clinical setting in 1998, PET (Positron Emission Tomography)/CT (Computed Tomography) fusion imaging has become the modality of choice for diagnostic imaging, including staging of cancer and tumors, as well as localizing seizures and diagnosing Alzheimer’s disease. By combining the two units, PET/CT manufacturers have decreased patient scan times, costs, and radiation dose amounts significantly. Integrating the software on the two units has been a key factor in making the entire concept work.1

With the introduction of this equipment came the development of a consensus group and task force to discuss the direction and educational needs of this rapidly expanding profession. The consensus group consisted of representatives from the ASRT (American Society of Radiologic Technologists), the SNMTS (Society of Nuclear Medicine Technologists Section), the NMTCB (Nuclear Medicine Technology Certification Board), and the ARRT (American Registry of Radiologic Technologists). Participants also included technologists, physicians, educators, and representatives from state regulatory agencies, hybrid fusion equipment manufacturers, radiopharmaceutical supply representatives, educational accreditation agencies, certification bodies, and professional associations.

The group discussed ways to unite the fields of CT and nuclear medicine, and established a plan for safely managing this rapidly growing field. They determined that as fusion imaging grew, there would be many questions concerning the training and educational requirements and safety of those personnel operating the new hybrid equipment. Their goal was to make recommendations in the form of consensus statements to ensure safe exams for patients, and safe equipment operation from qualified technologists.2 It is hoped that as the field of PET/CT fusion imaging continues to grow, a more formal educational approach will be taken.

History and Evolution of PET/CT

CT dates back to the late 1960’s developed by both Hounsfield and Cormack. CT quickly became an integral part in diagnostic imaging, particularly in trauma. PET was first developed in the early 1970’s and was used primarily for neuroscience research. It wasn’t introduced into the clinical setting until 1998. PET and CT were clearly the best choice for modality integration due to the ease of incorporating their processing and software techniques, as opposed to PET/MRI (Magnetic Resonance Imaging), having to deal with a magnetic field.1 Combining PET/CT would provide the best of both worlds, anatomy and function.

In May 1998 the first PET/CT scanner prototype, a spiral CT scanner (Somatom AR.SP) with PET components (the ECAT ART), was placed at the University of Pittsburg.3 Over 300 cancer patients were examined between May 1998 and August 2001.3 The prototype program was so successful that it was approved for whole body scans by the Food and Drug Administration (FDA) in the year 2000. The prototype unit was replaced by a permanent scanner called the Biograph (Siemens Medical Solutions), similar to the one pictured in Figure 1a. Several other manufacturers followed suit with their own models including the ECAT Reveal by CTI Inc., the Discovery LS by GEMS, and the Gemini by Phillips, all of which made significant improvements over the prototype scanner.3 All commercial PET/CT scanners are currently available with multi-slice CT technology.2

The concept of PET is based on the annihilation principle. Radionuclides allow the annihilation of positrons with an electron through a metabolic process. Radiopharmaceuticals such as fluorodeoxyglucose (FDG) interact with the body, and these interactions can be followed, mapped, and measured with scintillation detectors and gamma cameras.

In the 1970’s, PET scans were based on various geometrical configurations of thalium-activated sodium iodide crystals. A gamma camera was used to detect the photons, but the sodium iodide crystals were thin and resulted in poor resolution. In the late 1970’s bismuth germinate (BGO) was used to create better resolution. By the late 1980’s, the BGO block detectors became a standard scintillator. The development of newer more efficient scintillators such as gadolinium oxyorthosilicate (GSO) and lutetium oxyorthosilicate (LSO), have significantly increased PET/CT scanners patient throughput.4

Typical protocol for a PET/CT fusion scan consists of an initial injection of FDG tracer followed by a one-hour uptake period in a calm, quiet, environment. The patient is then placed on the couch of the scanner and a topogram (scout) is acquired. Scan ranges are selected for both PET and CT studies as the patient continues to breathe shallowly. The CT portion of the scan is completed first, then the PET portion, and finally the fusion reconstruction portion (Fig.1a-1e). Reconstructed fusion images are available to the physician and technologist for viewing within just a few minutes. Multi-detectors have allowed for volume rendering PET and CT acquisition. Studies are able to be viewed in the axial, coronal, and sagittal planes.1 Maximum intensity projections (MIP) on certain types of software, allow radiologists to view PET exams in 3-D images that rotate and can be visualized at every angle. Processing and software for typical PET/CT scanners has been standardized to comply with Digital Imaging and Communications in Medicine (DICOM) and transfer to Picture Archiving and Communication Systems (PACS) or to radiation therapy planning systems.1

image001a image001b
Fig. 1.a. - Siemens Biograph Sensation Model 16 PET/CT scanner Courtesy of Siemens Corp. Fig. 1.b. - MIP (Maximum intensity projection)

image001c image001d image001e
Fig. 1.c. - PET scan portion Fig. 1.d. - CT portion Fig.1.e. - PET/CT Fusion

PET/CT’s high-resolution imaging continues to improve from first generation type scanners to multi-slice technology.5 Energy resolution and spatial resolution have both improved due to scintillator upgrades and the concept of co-registered images. Simultaneous scans allow for accurately aligned images and quicker scan times for patient comfort. Fusion scan times have been reduced and may now be as short as 10 minutes. Not only is PET/CT imaging important in diagnosing, staging, and treating cancer, but it is also a valuable tool in disease management and localization. What PET and CT alone may not have been able to achieve, PET/CT fusion has reliably attained.

Future Direction and Expectations of PET/CT

The number of PET/CT scanners is expected to increase dramatically within the next few years. In 2002 there were approximately 150 PET/CT units worldwide.2 Fusion imaging procedures will commensurately increase due to PET/CT fusion scanners capability to aid physicians in targeting radiation therapy plans.6 Many physicians feel that PET/CT is now the modality of choice for fast, accurate diagnosis, and/or staging of cancer.

It is hoped that fusion imaging will take on a team approach from radiologists and technologists representing both diagnostic imaging and nuclear medicine fields.5 Ideally, PET/CT operators would be dually certified in both CT and nuclear medicine, but few technologists have credentials in both. According to the ARRT in 2002, the number of certified CT/nuclear medicine technologists was less than 200 in the nation.2

Fusion imaging generally takes place after an initial CT or MRI assessment. The amount of time a patient spends in the scanner combined for both studies can be as much as one to two hours. The acquisition time for a combined PET/CT exam is shorter than a PET scan alone. In 1998, a patient could expect to be in a fusion scanner alone for 45 to 60 minutes with a cost of nearly $3,000. In 2005, a patient could expect scan times to be as short as 10 to 20 minutes with a cost of about $1,800.7 As fusion technology continues to improve, acquisition times and patient costs will continue to decrease .7

The Need for Educational Development

Due to the overwhelming expansion of the PET/CT concept, it was soon evident that there was a need for educational direction. The SNMTS and the ASRT convened a consensus conference on July 31, 2002 in New Orleans, Louisiana to discuss personnel issues involved for performing fusion imaging. Due to the lack of any “formal education” in place, a task group was appointed by the ASRT and the SNMTS to determine the appropriate levels of education, training, and core competencies required for PET/CT equipment operators, along with the focus of reducing radiation dose to patients and personnel.6 The task group consisted of representatives from the ASRT, the SNMTS, the NMTCB, and the ARRT.2 Other participants at the conference included various technologists, physicians, educators, representatives from state regulatory agencies, hybrid fusion equipment manufacturers, radiopharmaceutical supply representatives, educational accreditation agencies, certification bodies, and professional associations. The goal of the consensus group was to develop “specific recommendations for the education and regulation of personnel who operate hybrid imaging equipment”.2 The task group would also review and evaluate existing training materials and recommend the most appropriate method for delivering educational material.2

Two consensus statements emerged from the meeting. The first consensus statement explored personnel qualified to operate PET/CT equipment. “Any registered radiographer with the credential R.T.(R), registered radiation therapist with the credential R.T. (T), or registered nuclear medicine technologist with the credentials R.T. (N) or Certified Nuclear Medicine Technologist (CNMT) may operate PET/CT equipment after obtaining appropriate additional education and training, and demonstrating competency”.2 Instead of requiring technologists to become dually certified, they recommended that multiple pathways be created to educate and train R.T.(R), CNMT, and R.T. (T) to operate the hybrid equipment. The second consensus statement explored regulation of personnel who operate PET/CT equipment. “States that do not currently license radiographers, nuclear medicine technologists, or radiation therapists are encouraged to adopt laws that regulate the education and credentialing of these individuals”.2 It was noted that licensure laws for technologists vary from state to state, and are generally in place for the protection of the public to ensure equipment operation only by qualified individuals. The consensus group did not recommend dual certification or require two technologists be present when one could perform the exam. This type of limitation might pose a barrier to patient access.

Consensus participants also recommended that all states adopt a uniform PET/CT licensure policy until the Consumer Assurance of Radiologic Excellence (CARE) Bill is enacted.2 If enacted, this Bill would ensure a minimum regulatory standard for personnel of all states who plan or perform any type of diagnostic imaging exam, except ultrasound. The Bill, sponsored by Rep. Heather Wilson and Sen. Michael Enzi, moved to the Senate on June 5, 2003 and is awaiting ratification.8 Professional societies were also advised by the consensus group to review their position statements, standards, and any documents that may need to be brought in line with the previous recommendations of the group. These consensus statements became the first steps toward proper training and education of technologists in the new world of fusion imaging.

“A PET/CT Project Group meeting was convened by the ASRT and SNMTS to identify the skills and knowledge required for technologists performing PET/CT studies and to recommend educational pathways for technologists to transition to PET/CT.”12 The PET/CT curriculum was a product of this meeting.12 The ASRT and the SNMTS published and copyrighted the new curriculum in 2004. The document is divided into three sections:

1.) Foundations,

2.) Content Specifications for basic Nuclear Medicine and Computed Tomography, and

3.) PET for dual modality imaging.

The foundations section of the manual represents pre-existing skills and knowledge of entry-level technologists from educational experiences and professional practice for registered radiologic technologists and nuclear medicine technologists. It covers such courses as: Computers in Radiologic Sciences, Contrast Media, Ethics and Law in the Radiologic Sciences, Human Diversity, Human Structure and Function, Image Analysis, Imaging and Processing, Medical Terminology, Patient Care in Radiologic Sciences, Pharmacology and Drug Administration, Radiation Biology, Radiation Production and Characteristics, Radiation Protection, and Sectional Anatomy (Table 1).12 Content specifications are outlined for: Basic nuclear medicine and PET for Dual Modality Imaging, and Basic CT and PET for Dual Modality Imaging. A Gap Analysis is included within the manual to help technologists determine where they currently fall within the training process, and what skills and educational elements may still be required in order for them to become certified (Table 1).12

Table 1

PET/CT/NM Curriculum

Foundations Number of Foundations Content Objectives Content Specifications for NM/PET Content Specifications for CT/PET Gap Analysis Of content
Computers in Rad. Sciences 10 Radiation. Protection Patient Care Radiation. Protection
Contrast Media 9 Radionuclides Patient Assessment Radionuclides Radiopharmaceuticals
Ethics & Law Rad. Science 27 Instrumentation QC Radiation Protection CT Instrumentation QC
Human Diversity 13 Diagnostic Procedures Computers Patient Care
Human Structure & Function 100   The CT Computer Radiation Protection
Image analysis 15   Image Quality in CT Computers
Imaging & Processing 24   CT Process The CT Computer
Med. Terminology 5   Spiral CT Image Quality CT
Patient Care 48   Physics/Instrumentation CT Process
Pharmacology & Drug admin. 18   System Operations Components Spiral CT
Radiation Biology 16   CT Applied Terminology Physics/Instrumentation
Radiation Production & Characteristics 17   Cross Sectional Anatomy System Operations Components
Radiation Protection 20   Procedures Protocol Applied Terminology
Sectional Anatomy 5   Procedures /CT Cross Sectional Anatomy CT-Pathology
        Procedure Protocol
        Procedures CT

In conjunction with the new educational curriculum, the NMTCB had been designated to develop a PET exam in early 2001. The original concept was to assess the nuclear medicine technologist’s knowledge of and experience in PET.11 As part of the consensus group, the NMTCB worked closely with the ARRT to agree upon what criteria would have to be met in order to sit for the PET certification exam. An NMTCB press release in October of 2003 announced the plans for the first administration of the PET Specialty Exam.10 In September. 2004, the first PET certification exam was administered only to qualifying Nuclear Medicine technologists. The results from 203 individuals tested were: 105 passing, and 98 failing (only a 52% pass rate).11 These results proved the desperate need for additional training and education prior to testing in order to achieve a more positive outcome for technologists. With these less than adequate results, the ASRT, ARRT, SNMTS, and the NMTCB felt the need to expand eligibility requirements to better accommodate the rapid growth of PET/CT. Beginning in 2005, the PET registry exam will no longer be limited to just nuclear medicine technologists. Any registered nuclear medicine technologist, registered radiologic technologist, or registered radiation therapist who has met the necessary clinical and advanced educational requirements set forth within the PET curriculum manual and clinical requirements set forth by the ARRT will be allowed to take the PET exam.11

“There are currently no formal education programs in existence for PET/CT.”19 The curriculum developed and copyrighted by the ASRT and the SNMTS to date, has not been adopted by any educational facilities. Additional training opportunities exist with manufacturers of PET/CT equipment such as on and off site equipment training by PET and CT experts, and preceptorship sites positioned around the country for operators to learn the clinical aspects of PET/CT from expert users. Some manufacturers also offer continuing education programs around the country for physics, image interpretation, equipment operation, clinical protocols and post processing techniques.17 Equipment manufacturers and regulatory agencies predict that as the field continues to mature, there will be a development of more formal education programs available to assist technologists with the transition to dual certification.2

Exam Certification Requirements

Candidates seeking PET certification should review the entire curriculum manual and utilize the gap analysis to determine the proper educational pathway within their perspective field. Each individual may require varying amounts of additional skills and education in order to operate PET-CT equipment and become certified.12 Technologists must be competent in all aspects in order to ensure a safe, quality exam with the minimum amount of radiation exposure.12

The initial recommendation from the consensus group was that exam applicants hold a current certification as NMTCB, CAMRT, or ARRT (N), and have 700 hours of documented experience operating PET or PET/CT scanner performing all aspects of imaging, injection, and handling radiopharmaceuticals.11 Beginning in 2005, those qualifying registered radiologic technologists and registered radiation therapists will also be allowed to sit for the PET certification exam. Technologists would need to provide the ARRT with proof of completion of 45 hours didactic education in the following subjects prior to being able to obtain certification: 15 hours nuclear radiopharmaceuticals, 15 hours PET, CT, and nuclear medicine radiation safety, and 15 hours in PET and CT instrumentation. The exam fee is $200.00 and individuals are allowed four hours to complete the test instead of three.11 The PET certification exam created by the NMTCB consists of five major categories: Diagnostic Procedures (~44%), Instrumentation/Quality Control (~30%), Radiation Protection (~10%), Radiopharmaceuticals (~15%), and Emergency Care (~1%)(Fig. 2).10 Other topics outlined within exam content materials are: various types of procedures, diagnostic radiopharmaceuticals, miscellaneous pharmaceuticals, interventional pharmaceuticals, and various types of equipment.10

Fig 2.

Technologists who successfully pass the exam will earn the PET credential. Certification period is seven years from the original exam date, after which time, it will expire and the individual must retest to maintain certification.11 The examination is not mandatory for nuclear medicine technologists; however, it would be a means for them to obtain continuing education credits or for professional growth. Qualified applicants also have the opportunity to take accredited advanced certification courses in PET and PET/CT fusion imaging at various educational facilities across the country.11,12 These courses can help prepare technologists for the PET examination and to be better qualified technologists in this rapidly growing field. The CT registry will be expanded to include nuclear medicine as a supporting category in 2005. A revised CT examination will be introduced in 2005 that will include areas such as: radiation physics, protection, and some safety components.13


Technologists have a new outlook on the growth of their profession. As training and educational programs are created, technologists will have the opportunity for dual modality certification, and to become much more valuable to their facilities.

Despite the increased full body dose of ~1.7rem EDE (Estimated Dose Equivalent), which is equal to about 833 chest x-rays or 5.5 years of background radiation, physicians agree that PET/CT fusion imaging is still the best tool, overall, to assess certain types of cancer.8,18 Patient dose is actually lower with combined PET/CT acquisition than with separate PET and CT acquisition studies.

Advancements in software, acquisition methods, and reconstruction of images have allowed a reduction in patient scan time by as much as fifty percent. The patient may only be in the scanner for potentially 10 – 15 minutes as opposed to 50 minutes. Early detection capability is saving patients needless treatments and insurance agencies needless costs.

Additional information provided from PET/CT fusion images enables health care providers to reclassify tumors as malignant or benign, diagnose Alzheimer’s patients, localize epileptic seizures, and even shorten certain surgical procedures.9 These factors are among some of the many advantages of PET/CT fusion imaging and its capability to increase diagnostic certainty.16


There is a serious need for formal education programs in the field of PET/CT. The rapid development of this technology has left our technologists untrained, uneducated, and unsure of their capabilities. Even though a formal curriculum now exists for PET certification, there are no educational institutions yet established to award a diploma or advanced certification degree in this area of expertise. The technology has seemingly exceeded the educational level of the technologists who are supposed to operate them.

There are some concerns that hybrid systems may encourage unnecessary patient dose. This is due to patients who have previously received a CT in addition to their recommended PET/CT scan. With the rapid development of equipment to accommodate fusion imaging, there will be less need for prior CT assessment studies.

Other disadvantages related to the new technology may include: finding radiologists that are dually qualified to dictate PET and CT images, availability of the radiotracer FDG (short half-life can present a barrier to some facilities), providing the needed space for the larger PET/CT equipment is sometimes difficult for certain facilities, special rooms are needed for dosing and allowing patients to relax during the FDG uptake period (~ one hour), and possibly the largest disadvantage for most facilities, the cost. Hybrid equipment is very expensive. A typical PET/CT fusion scanner could run anywhere from $1.9 million to $2.4 million, depending on the configuration of the unit. This is not including additional costs for increased interpretation times for Radiologists.9


PET/CT fusion imaging is redefining the way we view diagnostic imaging. Not only is it important in diagnosing, staging, and treating cancer, but it is also a valuable tool in disease management and localization. The integration of PET, CT, nuclear medicine, and radiation therapy technology and practices, has not only changed the way we look at medicine, but will also directly guide our technologists down an educational pathway in becoming more qualified and properly trained to operate this new hybrid equipment.

With a structured PET curriculum and PET certification exam in place, technologists can determine exactly what type of training is necessary to become PET certified. It is hoped that soon formal education programs will begin to form, and technologists may receive a diploma or even a degree in PET/CT fusion imaging.

The rapid growth of hybrid technology will have some drawbacks. As technology continues to advance, and the profession continues to grow, regulatory agencies will need to closely monitor progress, as we become one step closer to educating the hybrid technologist.


  1. Townsend D., Beyer T. A combined PET/CT scanner: The path to true image fusion. Br J Rad. 2002; 75, S24-S30.

  2. American Society of Radiologic Technologists and Society of Nuclear Medicine Technologist Section. Fusion imaging: a new type of technologist for a new type of technology: Statements from the PET-CT consensus conference. 2002, July 31. Available at: Accessed: October 18, 2004.

  3. Townsend D., Beyer T., Blodgett T. PET/CT scanners: A hardware approach to image fusion. Seminars in Nuc. Med. XXXIII(3), 2003;193-204.

  4. Townsend D. Physical principles and technology of clinical PET imaging. Annals of the Am. Acad. Med., March, 2004;(33) 2, 133-145.

  5. Townsend D., Carney J., Yap J., Hall N. PET/CT today and tomorrow. J Nucl Med. 2004; 45 (Suppl), 4S-14S.

  6. Volkin L. Conference issues recommendations for fusion imaging personnel. October 9, 2002 Available at: Accessed October 23, 2004.

  7. Messa C., Bettinardi V., Picchio M., Pelosi E., Landoni C., Gianolli L, et al.. PET/CT in diagnostic technology. Qtly J Nuc. Med. Mol. Im. 2004; 48(2), 66-75.

  8. Consumer Assurance of Radiologic Excellence Act of 2003, S. 1197, 108th Cong., 2003.

  9. Racette K. Fusion imaging: present technology and future needs. Jan. 6, 2003. Available at: index.aspx Accessed October 23, 2005.

  10. Nuclear Medicine Technology Certification Board 2004. NMTCB specialty exam- positron emission tomography examination content outline. Available at: Content Outline.htm Accessed October 23, 2004.

  11. Thomas K. PET exam - 2004. NMTCB News, 2004; 18(1). Available at: Spring 04.pdf. Accessed October 18, 2004.

  12. American Society of Radiologic Technologists and Society of Nuclear Medicine Technologist Section 2004. Positron emission tomography (PET) - computed tomography (CT) Curriculum. Reston, VA.

  13. Hendricks K. PET/CT imaging ‘fuses’ NMT to CT - ARRT to open computed tomography eligibility to nuclear medicine technologists 2004. Available at: Accessed November 17, 2004.

  14. American College of Radiology. Nuclear medicine/PET accreditation program requirements. Dec. 17, 2004. Available at: Accessed February 23, 2005.

  15. Martin M. Site planning and shielding design for PET/CT. Presentation given at the National Symposium on Fusion Imaging and Multimodalities: Technical and Regulatory Considerations Feb. 18-20, 2004. Available at: Accessed February 10, 2005.

  16. National Symposium on Fusion Imaging and Multimodalities: Technical and Regulatory Considerations Feb. 18-20, 2004. Available at: Accessed February 10, 2005

  17. Schumann, Silke - Marketing and Educational Development, Siemens Medical Corporation

  18. Plott, Carmine - Ph.D., CHP Forsyth Medical Center; Winston-Salem, NC

  19. Wilson, Bettye - M.ED,R.T.(R)(CT), RDMS, FASRT, Associate Professor, School of Health Related Professions at the University of Alabama at Birmingham


Figure 1a. - Siemens Biograph-Sensation Model 16 PET/CT fusion scanner. Photo courtesy of Siemens Med. Corp.

Figure 1b. - MIP (Maximum Intensity Projection) obtained from PET portion of scanner. Image courtesy of Riverside Regional Medical Center.

Figure 1c. - Cross sectional PET image on a patient with breast cancer. Image courtesy of Riverside Regional Medical Center.

Figure 1d. - Cross sectional CT image on same patient at exact same level. Image courtesy of Riverside Regional Medical Center.

Figure 1e. - Cross-sectional overlay of fused PET and CT images showing “hot spots” or FDG uptake from PET, with exact anatomical location from CT. Image courtesy of Riverside Regional Medical Center.

Figure 2 - Pie chart representing NMTCB PET Exam Content. Represented in percentage. Information courtesy of PET Specialty Exam component summary developed by the NMTCB, October 2003.

Table 1 - Breakdown of PET/CT/NM Educational Curriculum reflective of required objectives and specifications for designated area of study. Developed and sponsored by the ASRT and the SNMTS, Copyrighted in 2004 by the ASRT and SNM.

-- Please note: This article is either under construction or in the approval process. There will be no credit available for this article until the approval process has been completed. Passing the test for this article before the approval process has been completed WILL NOT result in full credit being awarded when the approval process has been completed. You must pass the test for this article after the approval process has been completed in order to receive credit for this article.

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