Imaging dose in radiation therapy has traditionally been ignored due to its low magnitude and frequency in comparison to therapeutic dose used to treat patients. The advent of modern, volumetric, imaging modalities, often as an integral part of linear accelerators, has facilitated the implementation of image-guided radiation therapy (IGRT), which is often accomplished by daily imaging of patients. Daily imaging results in additional dose delivered to patient that warrants new attention be given to imaging dose. This review summarizes the imaging dose delivered to patients as the result of cone beam computed tomography (CBCT) imaging performed in radiation therapy using current methods and equipment. This review also summarizes methods to calculate the imaging dose, including the use of Monte Carlo (MC) and treatment planning systems (TPS). Peripheral dose from CBCT imaging, dose reduction methods, the use of effective dose in describing imaging dose, and the measurement of CT dose index (CTDI) in CBCT systems are also reviewed.

Goblirsch, M., Mathews, W., Lynch, C., Alaei, P., Gerbi, B. J., Mantyh, P. W. and Clohisy, D. R. Radiation Treatment Decreases Bone Cancer Pain, Osteolysis and Tumor Size. Radiat. Res. 161, 228–234 (2004).Radiotherapy is the cornerstone of palliative treatment for primary bone cancer in animals and metastatic bone cancer in humans. However, the mechanism(s) responsible for pain relief after irradiation is unknown. To identify the mechanism through which radiation treatment decreases bone cancer pain, the effect of radiation on mice with painful bone cancer was studied. Analysis of the effects of a 20-Gy treatment on localized sites of painful bone cancers was performed through assessments of animal behavior, radiographs and histological analysis. The findings indicated that radiation treatment reduced bone pain and supported reduced cancer burden and reduced osteolysis as mechanisms through which radiation reduces bone cancer pain.

GammaTile cesium-131 (131Cs) permanent brain implant has received Food and Drug Administration (FDA) clearance as a promising treatment for certain brain tumors. Our center was the first institution in the United States after FDA clearance to offer the clinical use of GammaTile brachytherapy outside of a clinical trial. The purpose of this work is to aid the medical physicist and radiation oncologist in implementing this collagen carrier tile brachytherapy (CTBT) program in their practice. A total of 23 patients have been treated with GammaTile to date at our center. Treatment planning system (TPS) commissioning was performed by configuring the parameters for the 131Cs (IsoRay Model CS-1, Rev2) source, and doses were validated with the consensus data from the American Association of Physicists in Medicine TG-43U1S2. Implant procedures, dosimetry, postimplant planning, and target delineations were established based on our clinical experience. Radiation safety aspects were evaluated based on exposure rate measurements of implanted patients, as well as body and ring badge measurements. An estimated timeframe of the GammaTile clinical responsibilities for the medical physicist, radiation oncologist, and neurosurgeon is presented. TPS doses were validated with published dose to water for 131Cs. Clinical aspects, including estimation of the number of tiles, treatment planning, dosimetry, and radiation safety considerations, are presented. The implementation of the GammaTile program requires collaboration from multiple specialties, including medical physics, radiation oncology, and neurosurgery. This manuscript provides a roadmap for the implementation of this therapy.