Dosimetric comparison of high dose rate brachytherapy and intensity-modulated radiation therapy for cervical carcinoma

Abstract

Intracavitary brachytherapy is an integral part of radiotherapy for locally advanced gynecologic malignancies. A dosimetric intercomparison of high dose rate intracavitary brachytherapy (HDR_BT) and intensity-modulated radiotherapy in cervical carcinoma has been made in the present study. CT scan images of 10 patients treated with HDR_BT were used for this study. A sliding-window IMRT (IMRT_SW) and step-and-shoot IMRT plans were generated using 6-MV X-rays. The cumulative dose volume histograms of target, bladder, rectum and normal tissue were analyzed for both techniques and dose distributions were compared. It was seen that the pear-shaped dose distribution characteristic of intracavitary brachytherapy with sharp dose fall-off outside the target could be achieved with IMRT. The integral dose to planning target volume was significantly higher with HDR_BT in comparison with IMRT. Significant differences between the two techniques were seen for doses to 1 cc and 2 cc of rectum, while the differences in 1 cc and 2 cc doses to bladder were not significant. The integral doses to the nontarget critical and normal structures were smaller with HDR_BT and with IMRT. It is concluded that IMRT can be the choice of treatment in case of non-availability of HDR brachytherapy facilities or when noninvasive treatments are preferred

Evaluation of MLC leaf positioning accuracy for static and dynamic IMRT treatments using DAVID in vivo dosimetric system*

“…For the both patient groups, sMLC_IL5 showed higher heterogeneity in PTV dose distribution than the others. These results are supported by the study performed by Shwetha et al (14) in which the performances of dynamic and static MLC‐based IMRT and high‐dose‐rate brachytherapy were compared for cervical carcinoma. They found that the IMRT plans based on sMLC_IL5 had the lowest HI performance with the average HI of $1.29\pm 0.13$ while the other IMRT plans based on dMLC, sMLC_IL10 and sMLC_IL20 had the average HI in the band of 1.19‐1.21.…”

Equivalent physical dose (EPD) for improved precision in voxelized dosimetry

“…Significant deviations may be most common in treatment techniques with steep dose gradients such as stereotactic body radiation therapy (SBRT), where dose decreases nearly isotropically in and around the target, 14 or high dose rate (HDR) brachytherapy, where absorbed dose in some voxels near the source can exceed the prescription dose by 200%. 15,16 Overall, such as when taking the mean dose across a structure, some of these errors may cancel out and this may account for the acceptance of the existing models to date, particularly in parallel organs, where the volume effect plays a greater role. 17 However, in serial organs such as the spinal cord, the accuracy of dosimetry at the voxel level is critical.…”

IMRT and brachytherapy comparison in gynaecological cancer treatment: thinking over dosimetry and radiobiology

“…Important to note, when comparing OARs doses, the value of D 2cm 3 was always lower for ICBRT respect to IMRT. Several investigators [45,46] compared dosimetric parameters of the entire external OARs volumes with those of only the OARs wall volumes both for urinary bladder and rectum. When the volume of 2 cm 3 is considered, the D 2cm 3 values computed for the external contours are almost identical to the D 2cm 3 values for the organ wall.…”