[Dosimetry with phantom for total body irradiation(TBI)].

ABSTRACT

Total body irradiation(TBI) is being used as a method of preparation for bone marrow transplantation(BMT). In TBI, the dose calculation is based on dosimetry using a phantom. We measured the basic dose with a phantom using a 10 MV X-rays. We confirmed the accuracy of the dose calculation performed in our facilities and investigated a method of more accurate dosimetry. We measured the variation in dose according to the size of the phantom and the depth using a tough water phantom, and examined the difference in TMR according to SCD, field size, and size of the phantom. Consequently, the dose has been changed regardless of the size of the phantom at larger than 80 x 30 x 30 cm(3), and it is about 1% larger than 30 x 30 x 30 cm(3). Also TMR has changed according to various conditions, including the size of the phantom, field size, and SCD. Therefore, it was found that dosimetry using the 30 x 30 x 30 cm(3) phantom leads to underestimation in dose calculation, and there is no difference in dose between the field size of 151.5 x 160 cm(2) and 151.5 x 80 cm(2). It is also necessary to consider the effect of the vertical size of the phantom.