Dose rate influence on deep dose deposition using a 6 MV x-ray beam from a linear accelerator

Abstract

Linear accelerators used in radiation therapy treatments usually provide the capability of irradiating with different dose rates. The medical physicist may choose arbitrary the dose rate to use, although the relative biological effectiveness (RBE) varies with this physical parameter. In this work the measurements of absorbed dose of the x-ray beams from a Varian 6 MV linear accelerator CLINAC 600C/D were made in a water phantom, using an appropriate dosimetry system, consisting of an electrometer and a waterproof ionization chamber. The code of practice for dosimetry used in this work is the IAEA (International Atomic Energy Agency) TRS-398, since water relates closely to the biological effects of radiation. The measurements were made in three depths, with three different field sizes and six different dose rates. The data were treated and the graphs show the obtained results. Different dose rates changes the deep dose deposition at the same depth and this must be considered in the planning.

X-rays sensing properties of MEH-PPV, Alq3 and additive components: A new organic dosimeter as a candidate for minimizing the risk of accidents of patients undergoing radiation oncology

“…In the present study, Varian Clinac 600C LINAC computer-controlled equipment with a conventional X-rays source was used. This machine generates a 6 MV X-rays beam with rectangular symmetric fields [18] and delivers the exact prescribed dose to the patient in the lowest number of monitor units. The irradiation of samples was performed in a water phantom according to IAEA TRS 398 dosimetry protocols [19] at a source-surface distance of 100 cm with a (30 cm × 30 cm) field in order to simulate the standard conditions of cancer treatment.…”

X-ray dose detector based on color changing of light-emitting polymer–metal complex hybrid material

“…In the present study, Varian Clinac 600C LINAC computer-controlled equipment with a conventional X-ray source was used. This machine generates a 6 MV X-ray beam with rectangular symmetric fields [11] and delivers the exact prescribed dose to the patient in the lowest number of monitoring units. The irradiation of samples was performed in a water phantom according to IAEA TRS 398 dosimetry protocols [16] at a source-surface distance of 100 cm with a (30 × 30) cm 2 field in order to maintain the chief conditions of cancer treatment.…”

“…When these mistakes occur, they can be fatal; it is critical to prevent such errors in this extremely important field. Previous work by the American Association of Physicists in Medicine and the American Society of Radiation Oncology supports the view that "error reporting systems should be developed in radiation therapy" to "protect the safety of each and every patient" [8][9][10][11]. From this point of view, an easy-to-use, easy-to-read and low-cost dosimeter, that is also more accessible to people in places with limited resources, may ensure that every treatment will be as safe as possible.…”

Design of a multi-channel photonic crystal dielectric laser accelerator

“…The linear accelerators used for medical therapy usually operate on a dose rate around 1 Gy•min −1 [40]. If we assume a typical phantom mass of 1 kilogram and a typical electron beam final energy of 6 MeV, the required average beam current is 2.8 nA.…”