Image-guided radiation therapy: techniques and strategies

Enhanced Radiation Therapy with Multilayer Microdisks Containing Radiosensitizing Gold Nanoparticles

“…A variety of X-ray radiation techniques have been used to minimize dose on normal cells or maximize dose on cancer cells. ,, The dose can be fractionated over time to allow normal cells to recover, while cancer cells that are relatively radioresistive in the first treatment move into a relatively radiosensitive phase of cell cycle in the next treatment; the dose can be fractionated over space to intersect at tumors from several directions to spare normal cells along the beam path . Image-guided radiation therapy and intensity-modulated radiation therapy can be used to maximize X-ray doses on tumors and conform the tumor’s 3D shape with multiple beamlets of different intensity, respectively. , Alternative methods can be used to improve discrimination between tumor and normal tissues. , Radioprotective drugs have been used as free radical scavengers to protect normal cells from damage. , Radiosensitizers such as oxygen, oxygen carrying blood substitutes, and radiosensitive drugs have been used to enhance the effects of given X-ray doses . In particular, due to their large mass energy absorption coefficients, nanoparticles of heavy elements such as gold and platinum have been studied with the intention to enhance X-ray contrasts between normal and cancer cells. ,,, Although single gold nanoparticles can be delivered to cells for radiation therapy, free radicals generated around cells in some cases may not be sufficient to damage DNA and the uptake of nanoparticles by cells usually is influenced by the surface chemistry of nanoparticles or cell type. , On the other hand, if hundreds of thousands of nanoparticles could be placed in the vicinity of the cells, a large amount of free radicals will be available for DNA damage, and the total X-ray dose can be reduced to receive the same effect …”

“…15 Image-guided radiation therapy and intensity-modulated radiation therapy can be used to maximize X-ray doses on tumors and conform the tumor's 3D shape with multiple beamlets of different intensity, respectively. 16,17 Alternative methods can be used to improve discrimination between tumor and normal tissues. 18,19 Radioprotective drugs have been used as free radical scavengers to protect normal cells from damage.…”

Commissioning and Quality Assurance of an Integrated System for Patient Positioning and Setup Verification in Particle Therapy

“…Because IGRT improves precision (14,(17)(18)(19)(20)(21), dose hypofractionation becomes more feasible, leading to a reduction of the number of treatment sessions. Particle therapy, and especially carbon ion therapy, exhibits a consistent trend toward hypofractionation (9,22).…”

“…Without excluding the use of conventional patient immobilization devices such as vacuum bags, custom molds, rigid stereotactic head frames, rectal balloons etc., a modern center for particle therapy is usually equipped with integrated systems for high precision patient positioning and setup verification. Because IGRT improves precision (14,(17)(18)(19)(20)(21), dose hypofractionation becomes more feasible, leading to a reduction of the number of treatment sessions. Particle therapy, and especially carbon ion therapy, exhibits a consistent trend toward hypofractionation (9,22).…”