ABSTRACT
The purpose of this study was to evaluate feasibility of Vertical Multileaf Collimator for determination of irradiation size using Vertical Multileaf Collimator and lead block to determine 4 different irradiation shape in case of Co-60 gamma-ray and 6 MV X-ray. We chose ion chamber, glass dosimeter and EBT chromic film to compare with Vertical Multileaf Collimator results and lead block results. In case of Co-60 gamma-ray and 6 MV X-ray, the central axis point dose normalized at reference field of lead block with ion chamber results for Vertical Multileaf Collimator were estimated higher than lead block about 5.1%, 4.2%. In case of Co-60 gamma-ray, the central axis point dose normalized at reference field of lead block with glass dosimeter results for Vertical Multileaf Collimator were estimated higher than lead block about 2.2%, 7.8%, 7.2%, 4.0% for reference, circle, triangle, cross field, respectively. In case of 6 MV X-ray, the central axis point dose normalized at reference field of lead block with glass dosimeter results for Vertical Multileaf Collimator were estimated higher than lead block about 6.7%, 6.2%, 3.8%, 6.2% for reference, circle, triangle, cross field, respectively. The results of EBT chromic film, Vertical Multileaf Collimator of penumbra size for all irradiation shape was smaller than lead block of those size that 2.0~3.5 mm for Co-60 gamma-ray, 0.5~1.0 mm for 6 MV X-ray. The results from this study, radiation treatment volume that results in shielding block can be minimized. In addition, during radiation treatment for 2, 3-dimensional radiation therapy using a Vertical Multileaf Collimator of this survey can be used to determine variety of irradiation fields.
Subject(s)
Axis, Cervical Vertebra , Feasibility Studies , GlassABSTRACT
Objective To apply simulator image workstation to making and verification of integrated blocks.Methods The outline of blocks drawn by doctors at simulator image workstation were transferred to the auto-cutting machine.The blocks were fabricated and were verified by the simulator.Then the qualified ones were verified by the linear accelerator.Results Of 1 371 blocks selected to verify by the simulator,1 107 (80.7%) blocks were qualified;Of 1 371 blocks qualified by the simulator,1 345(98.1%) blocks were qualified by the linear accelerator.Conclusion Simulator image workstation can improve efficiency and reduce the error in making blocks.
ABSTRACT
Objective To investigate and carry out the function of the lead block validating instrument in the radiotherapy. Methods Based on clinical practice and the principle comparative steady STD and SAD of linear accelerator, the function of lead block validating instrument was developed in reason. Results The working quality and efficiency are greatly improved. Conclusion Not only the criterion extent of founded lead block and the proof of every kinds spume blocks in three-dimensional conformal radiotherapy and integer block radiotherapy and electron radiotherapy, but also the shadow tray centers and center reticle can be validated by the lead block validating instrument.
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Objective To apply lead block technology to the interdiction of X-ray destroy from linear accelerator to normal tissues and sensitive organs so as to treat large fields and irregular malignant lymphoma.Methods The steps were as follows:(1)immobilizing patients;(2)simulator photographing;(3)sketching targets;(4)tailoring lead block;(5)validating lead block.Results Problems of large fields and more targets were solved in radiotherapy for malignant lymphoma patients.Conclusion Based on clinical practice,new methods was found for realizing large irregular radiation fields.
ABSTRACT
Objective To detect whether the make of the low melting-point lead block coincides with the request of routine radiation treatment and check the quality control of this method.Methods To take a photograph of correcting sheet in modelling machine,low melting-point block of lead was fabricated after operator marking off the outline.Exposure perimete and blocked range were checked out and compared with correcting sheet after low melting-point block of lead was fixed.Results The methods with low melting-point block of lead acted as a blind in routine radiation treatment is convenience and accurate.Conclusion Low melting-point lead block acted as a blind is an effective method,which not only meets the requirement of designed proposal but also promotes the accuracy of radiation treatment.