About Physics at ABC

About Physics at Arizona Breast Cancer Specialists

Our Physics Department
Arizona Breast Cancer Specialists Department of Radiation Physics provides safe, accurate and high quality patient care in collaboration with the patient’s radiation oncologist. The department provides physics consultation regarding the scientific and technical aspects of radiation oncology, and ensures that state of the art technologies and equipment function optimally.

The Department of Radiation Physics has three Ph.D. medical physicists and three board certified medical dosimetrists, two medical physics residents, and medical physics graduate students from the University of Arizona.

Medical Radiation Physicists

The medical physicists are greatly involved with responsibilities in areas of medical imaging and treatment, often with specific patients.

An example is the planning of radiation treatments for cancer patients, using either external radiation beams or internal radioactive sources. An indispensable service is the accurate measurement of the radiation output from radiation sources employed in cancer therapy. Other important services are provided through investigation of equipment performance, design of radiation installations, and control of potential radiation hazards.

The Physics Department provides services at all three ABCS facilities located in North Scottsdale, South Scottsdale, North Phoenix, and Gilbert.

Medical Dosimetrists

The medical dosimetrist is a member of the radiation oncology team who has knowledge of the overall characteristics and clinical relevance of radiation oncology treatment and planning equipment, is cognizant of procedures commonly used in brachytherapy and has the education and expertise necessary to generate radiation dose distributions and dose calculations.

Communication among team members is vital to effective patient care. Toward this end, it is imperative that medical dosimetrists actively and openly communicate with radiation oncologists, medical physicists, radiation therapists, and nurses, among other members of the team, to enable and ensure that appropriate transfer of information occurs.

Medical dosimetrists frequently are liaisons between medical physicists and other members of the radiation oncology team.

Sonya Suzewitz, CMD

Sonya Suzewitz, CMD


Memberships – ASRT, ARRT
Sonya Suzewitz has been involved in all aspects of Radiation Oncology from treating patients to dosimetry since 1975.

She has spent most of the last 15 years working on External Treatment Planning, Breast Brachytherapy and Prostate Implants. She enjoys the opportunity to provide state-of-the-art technology in a continually evolving field.

Our Physics Team

Kevin Rogers, MS

Chief Physicist

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Alex Li, PhD, DABR

Medical Physicist

Dr. Li is a board certified medical physicist who graduated from the CAMPEP medical physics program at the University of California Los Angeles (UCLA).

Xiaoqiang Li, PhD

Medical Physicists

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Erika N. Nelums, DMP

Medical Physicist

After receiving her Bachelor of Science degree in physics, from Tuskegee University, Erika followed her interest in medicine and science and attended Vanderbilt University

Mei Sun


Memberships – ASRT, ARRT
Sonya Suzewitz has been involved in all aspects of Radiation Oncology from treating patients to dosimetry since 1975.

Radiation Safety Program

At Arizona Breast Cancer Specialists, one of the leading cancer centers in Arizona,much of the radiation is performed using X-ray or radioactive materials. To maintain a safe environment, minimize risks, and protect the health and safety of employees, patients, visitors, and the surrounding community, a radiation safety program is required. Under US Nuclear Regulatory Commission (NRC) licenses and Arizona Breast Cancer Specialists’ policies, the radiation safety program administers a comprehensive radiation safety program covering our three clinical facilitates in and around the Phoenix area. The radiation safety program provides for the effective supervision, control, and monitoring of all radioactive materials and X-ray radiation at Arizona Breast Cancer Specialists. This includes activities such as personnel monitoring, laboratory inspections, waste management, consultation, environmental monitoring, and training. As a result of this comprehensive program, exposure of Arizona Breast Cancer Specialists’ employees to external and internal radiation has been kept well below the NRC’s radiation dose limits and consistent with the NRCs As Low As Reasonably Achievable (ALARA) concept.

Patient Safety

Our comprehensive radiation therapy program confers with the highest standards of care due to the many qualitative controls currently in place to ensure safe and accurate delivery of treatments to our patients. The entire radiation therapy treatment process is complex, which involves multiple transfers of information and data between different highly qualified professional staff members, across various work areas, in order to deliver the radiotherapy treatment. With such a multi-integrated system, each procedure and stage necessitates a high level of accuracy at every step in order to minimize the occurrence of safety related incidents. By integrating some of the most technological advances of radiation therapy, we are able to improve dose conformity while significantly shortening treatment times and reducing dose to the patient’s normal tissues and organs. Here at the Arizona Breast Cancer Specialists, we prioritize patient safety by following these high levels of quality assurance that provide radiation therapy to patients and incorporate a rigorous and comprehensive set of safety rules.

These include:

  1. machine related quality assurance checks including a daily systems check of the beam output and emergency interlocks as well as physics checks of all equipment on a monthly basis;
  2. secondary calculations that verify the accuracy of the radiation dose calculated by our treatment planning systems;
  3. a review of all treatment plans by our highly qualified medical physics/dosimetry team;
  4. additional quality assurance checks of Intensity Modulated Radiation Therapy (IMRT) and Rapid Arc plans prior to treatment;
  5. checks by our therapy staff verifying agreement between the radiation dose in the treatment plan and the treatment console; and
    verification of the physician’s written directive, the prescribed dose and the patient’s identity.

While we know that all treatments pose some risks, the belief is that the benefits outweigh the risk, and patients should discuss these risks as well as the benefits with their doctors. Our staff is committed to the very highest standards in the delivery of radiation therapy to our patients. We continuously work to strengthen training, quality assurance and patient safety here at Arizona Breast Cancer Specialists. Please feel free to discuss your treatment plan and our quality assurance processes with your radiation oncologist or with any member of our staff.

Facilities and Technology

Facilities and Technology

Arizona Breast Cancer Specialists has four clinic locations in the Phoenix area: Deer Valley, North Scottsdale, South Scottsdale and the East Valley.

Each clinic boasts a state-of-the-art Varian linear accelerator; the East Valley clinic possesses a Varian True Beam linear accelerator with robotic capabilities. Additionally, each clinic boasts a modern Nucletron HDR brachytherapy afterloader in a dedicated brachytherapy procedure suite; a GE Lightspeed treatment planning CT scanner with full 4D and respiratory gating technology.

Each of our three clinics provides the full repertoire of modern radiation oncology treatment. These include: stereotactic radiotherapy (SRT/SBRT); intensely modulated radiation therapy (IMRT); high dose rate (HDR) brachytherapy, and of course state-of-the-art image guided radiation therapy (IGRT) and respiratory gating.

The TrueBeam linear accelerator at our Arizona Radiation Oncology Specialist’s, East Valley clinic, has particular skill in delivering stereotactic treatments to small cancers in delicate locations within the body. The TrueBeam unit is also coupled with the very successful Calypso System for prostate cancer, providing unprecedented accuracy in the treatment of prostate cancer.

Breast Brachytherapy Teaching and Training

Arizona Breast Cancer Specialists is proud to host the American Brachytherapy Society’s Brachytherapy Fellowship program, sponsored by Nucletron. This fellowship program is intended for physicians currently enrolled in a radiation oncology residents program at an accredited institution. The fellowship consists of one dedicated week at a facility where the visiting physician will undergo an intense immersion in clinical brachytherapy treatment. With six Radiation Oncologists, three PhD physicists, and an entire team dedicated to teaching advanced brachytherapy techniques, we are ideally suited for this educational experience. With new facilities and a full spectrum of applicators, devices, equipment, afterloaders, and methods, residents can expand their horizons by adding the oldest and most conformal means of RT delivery to their armamentarium.

Arizona Breast Cancer Specialists performs and/or treats an average of 16 HDR fractions each day. Many of these cases are considered quite challenging, such as interstitial brachy APBI adjacent to a breast augmentation implant. Residents should come prepared to be immersed in brachytherapy procedures, treatments, dosimetry, as well as lectures covering the rationale, background, and physics/clinical fundamentals of advanced brachytherapy.

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