The Team

Our team works together to provide you with quality medical and personal care

The Grand Lake Regional Cancer Center’s qualified staff includes Radiation Oncologists, Medical Physicists, Dosimetrists, a Radiation Oncology Nurse, and Radiation Therapists. Together with our office staff, these clinicians provide the knowledge and the personal care to provide a quality service to our patients. Our staff functions as a team, with each member contributing to the care of our patients.

Our Physicans

Sandra J. Herrington, PH.D, M.D.


During Dr. Herrington’s 20 year career in Radiation Oncology, she still shares her passion of delivering compassionate care to her patients, which is the reason she was initially drawn to the specialty of cancer care.  Dr.  Herrington joined the Grand Lake Regional Cancer Center and the Allison Radiation Oncology Center at St. Rita’s Medical Center in 2008, is currently Medical Director at both sites, and Chair of the St. Rita’s Cancer Committee 2015 to 2016. Dr. Herrington has extensive experience treating many cancers, and is specifically interested in utilizing medications and treatment techniques that minimize side effects while maintaining effectiveness of treatment.

Dr. Herrington was born in Michigan and has lived most of her adult life in Ohio.  She is a veteran of the US Air Force, and was previously a Captain at Wright Patterson Air Force Base, in the Radiation Oncology Department.  Dr. Herrington earned her Medical Doctorate and a Doctor of Philosophy from the University of Kansas and completed her residency at University Hospitals of Cleveland.

Married to Dan, she has two adult children, Eric and Becky.  In her spare time, Dr. Herrington enjoys the outdoors, listening to wild turkeys and ducks, watching birds, and gardening. She loves to beautify her surroundings, including her pond front home in Shawnee.

Our Staff

Dan Goecke, B.S., CMD

dan-goeckeDan has lived in Spencerville for 35 years. He graduated from Spencerville High School and studied at the University of Cincinnati. He has worked at Grand Lake Regional Cancer Center since 2005 as a Dosimetrist, doing computer-based treatment planning.

Dan is married to Sara, and together they have five children: four girls and one boy. In addition to being a Dosimetrist, Dan is a part-time farmer on his family farm.

Heidi Thees, Secretary

heidi-theesHeidi lives in Celina. She graduated from Celina High School and attended Wright State University, where she majored in medical office. She has worked at Grand Lake Regional Cancer Center since it opened in 2004.

Heidi is married to Tim, and together they own a small business within the Celina community. The couple has two children, Derek and Sara.

Heidi enjoys spending time with her family and friends, camping, working out, and has an extreme passion for working with the special needs community. Of her job at Grand Lake, she says, “I have the honor of working with a very caring and compassionate staff. Together, we treat patients ‘as a person and not a number!’”

Mary Jo Dues, RN, Radiation Oncology Nurse

mary-jo-duesMary Jo lives on a farm in St. Henry. She graduated from Lima Technical College as a Registered Nurse. Mary Jo has experience in emergency, family practice and hospice in addition to oncology. She has worked at Grand Lake Regional Cancer Center since 2006.

Mary Jo has been married to her husband Mark since 1989. Together they’ve had the joy of raising four children. Mary Jo’s hobbies include gardening, camping, biking, hiking, and spending time with her family and friends.

Kellie Pearson, RT(R)(T), Radiation Therapist

kellie-pearsonKellie lives in Celina, and graduated from Rhodes State College with an Associate Degree in Applied Science Radiography and from Washburn University with a degree in Radiation Therapy. She has worked at Grand Lake since 2004.

Kellie has been married to her husband Jason since 2003. They have three kids, Gavin, Bria, and Alexa. Kellie loves to attend her kids sporting events, and enjoys staying fit and healthy herself. She does CrossFit to stay in shape. Additionally, she loves to spend time with her friends and family.

Mandy Fleck, RT(R)(T), Radiation Therapist

mandy-fleckMandy lives in the Marion Local School District. She graduated from Sinclair Community College with an Associate Degree in Applied Science for Radiography and from University of Cincinnati with a degree in Radiation Therapy. Mandy has worked at Grand Lake since 2004.

Mandy has been married to husband Lester since 1997. They have four children, Collin, Sarah, Logan, and Sophia. Her hobbies include spending time with family and friends. She also loves the outdoors and cheering her kids on at their sporting events.

Jill Otte, RT(T), Radiation Therapist

jill-otteJill grew up in Fort Recovery and lives in Minster. She graduated in 2008 from Ball State University with an Associate Degree in Radiation Therapy and has worked at Grand Lake since 2009.

Jill has been married to her husband Douglas since 2010. Together they have three children, Aleah, Adalyn, and Dylan. Jill enjoys gardening, taking walks with family, and doing crafts. She also loves to decorate for the holidays. Of Grand Lake, she says, “We have a great staff and I really enjoy working with them.”

Karen Homan (RD, LD) Registered Dietician

Karen Homan (RD, LD) Registered DieticianKaren worked at GLRCC from 2005-2008 and rejoined our team in 2017. She obtained her Bachelor of Science in Health and Sports Studies from Miami University in Oxford, Ohio, in 2000. She completed a dietetic internship at Ball Memorial Hospital in Muncie, Indiana in 2001.

She lives in Chicasaw, Ohio, with her husband Bart and their five children: Brandt, Clara, Eva, Garret and Sierra. When she is not working, Karen enjoys being outdoors and staying physically active, cooking and trying new foods, playing with her children and spending time with friends and family.

Terms you need to know

Radiation Oncologist

A physician who has received specialty training in cancer treatment with radiation. The Radiation Oncologist decides the most effective treatment for the individual patient, and creates a custom treatment plan for each patient.

Medical Physicist and Dosimetrist

Staff that assist the Radiation Oncologist to calculate the appropriate radiation dose according to the doctor’s prescription. The physicist monitor the equipment’s accuracy and that the proper amount of radiation is being produced during treatments. The Dosimetrist is responsible for helping to plan the radiation treatment with the Radiation Oncologist, utilizing complex computer programs.

Radiation Oncology Nurse

The Radiation Oncology Nurse is specifically trained in the needs of cancer patients during their treatment. The nurse works closely with the Radiation Oncologist and is an excellent source of information for the patient and family.

Radiation Therapist

Radiation Therapists are licensed and trained to simulate (set-up) and deliver radiation treatments as prescribed by the Radiation Oncologist. The Radiation Therapists are responsible for making sure the patient is precisely lined up for treatment, giving the daily treatments, and monitoring daily and total doses