Radiation Dose Escalation in a Lung Tumor using FlowMotion
Dustin Osborne, PhD and Yong Bradley, MD, University of Tennessee, Knoxville, TN, USA | 2013-12-01
A 72-year-old female presented with headaches and respiratory symptoms. MRI and X-ray abnormalities were suggestive of lung cancer. The patient was referred for a Fludeoxyglucose F 18 (18F FDG)* PET/CT scan for staging. A wholebody PET•CT scan was performed using FlowMotion™** with respiratory gated acquisition for the thorax and was reconstructed with HD•Chest to eliminate respiratory motion.
1. HD•Chest image integrated into the whole-body acquisition with FlowMotion Technology shows a large lung tumor in the right lower lobe with necrotic center.
A whole-body PET•CT scan acquired using FlowMotion technology, which enables PET acquisition using continuous table motion, demonstrated a large 6.4 x 4.5 cm necrotic, right-lower-lobe primary mass with an SUV max of 27 with multiple mediastinal lymph node involvement. The image showed only a small necrotic region
with a volume of approximately 3 cc. Comparison of phase-matched respiratory gating to standard non-gated acquisition indicated that the dimensions of the lung mass were more accurately measured with integrated HD•Chest.
The mass measured 5.2 x 4.2 cm on HD•Chest with an SUVmax of 30 and multiple lymph involvement. HD•Chest imaging indicated a necrotic core volume of 6.5 cc (a more than two times increase in visualized necrotic core volume).PET•CT supported confirmation of large primary lung carcinoma with lymph involvement, and the patient was referred for radiation therapy (RT).
*Siemens' PETNET Solutions is a manufacturer of fludeoxyglucose F 18 injection (18F FDG). Indication and important safety information as approved by the US Food and Drug Administration can be found at the bottom of the page for 18F FDG, adult dose 5-10 mCi, administered by intravenous injection.
Radiation Therapy Plan
A typical RT plan includes only 100% of dose given to the tumor volume. For the large primary mass, the initial indicated volume appeared to be small onconventional whole-body PET/CT. This would have allowed only a standard conformal radiation therapy planning protocol. Because of FlowMotion and its ability to integrate HD•Chest (phase-matched gating) into one, single-routine, whole-body acquisition, the resulting primary lesion was shown to have a much larger necrotic mass, which could benefit from a customized dose painting strategy with dose to the hypoxic region with the highest SUVmax levels being increasedto approximately 130%.
Follow-up PET•CT indicated lesion changes consistent with positive therapeutic treatment response. The tumor size was decreased to 4.1 x 3.5 cm with an SUVmax of only 4.7 compared to an original SUVmax of 30. This study clearly demonstrates the added value of HD•Chest-based motion management in defining target volumes for RT in lung tumors, especially related to dose escalation strategies. FlowMotion enables precise definition of the range of gated acquisition and makes
routine use of HD•Chest possible, which may have an impact on dose escalation approaches for lung tumors, as well as tumors with significant respiratory motion components like liver tumors, pancreatic tumors, etc.
Scanner: FlowMotion Technology
Scan dose: 10 mCi (370MBq) 18F FDG
Scan delay: 90 minutes post injection
FlowMotion 4 zone protocol with variable table speed with HD•Chest for thorax
* Fludeoxyglucose F 18 Injection
INDICATIONS AND USAGE
Fludeoxyglucose F 18 injection (18F FDG) is indicated for positron emission tomography (PET) imaging in the following setting:
Oncology: For assessment of abnormal glucose metabolism to assist in the evaluation of malignancy in patients with known or suspected abnormalities found by other testing modalities, or in patients with an existing diagnosis of cancer.
IMPORTANT SAFETY INFORMATION
Radiation-emitting products, including fludeoxyglucose F 18 injection, may increase the risk for cancer, especially in pediatric patients. Use the smallest dose necessary for imaging and ensure safe handling to protect the patient and health care worker.
Blood Glucose Abnormalities
In the oncology and neurology setting, suboptimal imaging may occur in patients with inadequately regulated blood glucose levels. In these patients, consider medical therapy and laboratory testing to assure at least two days of normoglycemia prior to fludeoxyglucose F18 injection administration.
Hypersensitivity reactions with pruritus, edema and rash have been reported; have emergency resuscitation equipment and personnel immediately available.
Fludeoxyglucose F 18 Injection is manufactured by Siemens' PETNET Solutions, 810 Innovation Drive, Knoxville, TN 39732