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Comparison of CT ‐based volumetric dosimetry with traditional prescription points in the treatment of cervical cancer with PDR brachytherapy
Author(s) -
Lowrey Nicola,
Nilsson Sanna,
Moutrie Zoe,
Chan Philip,
Cheuk Robyn
Publication year - 2015
Publication title -
journal of medical imaging and radiation oncology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.31
H-Index - 43
eISSN - 1754-9485
pISSN - 1754-9477
DOI - 10.1111/1754-9485.12341
Subject(s) - medicine , brachytherapy , radiation treatment planning , dosimetry , cervical cancer , nuclear medicine , rectum , dose volume histogram , medical physics , medical prescription , radiology , cancer , radiation therapy , surgery , pharmacology
The traditional use of two‐dimensional geometric prescription points in intracavitary brachytherapy planning for locally advanced cervical cancer is increasingly being replaced by three‐dimensional (3 D ) planning. This study aimed to directly compare the two planning methods to validate that CT planning provides superior dosimetry for both tumour and organs at risk ( OAR s) in our department. Methods The CT planning data of 10 patients with locally advanced cervical cancer was audited. For each CT dataset, two new brachytherapy plans were created, comparing the dosimetry of conventional A merican B rachytherapy S ociety points and 3 D ‐optimised volumes created for the high‐risk clinical target volume ( HR CTV ) and OAR s. Total biologically equivalent doses for these structures were calculated using the modified EQD 2 formula and comparative dose‐volume histogram ( DVH ) analysis performed. Results DVH analysis revealed that for the 3 D ‐optimised plans, the prescription aim of D 90 ≥ 100% was achieved for the HR CTV in all 10 patients. However, when prescribing to point A , only 50% of the plans achieved the minimum required dose to the HR CTV . Rectal and bladder dose constraints were met for all 3 D ‐optimised plans but exceeded in two and one of the conventional plans, respectively. Conclusions This study confirms that the regionally relevant practice of CT ‐based 3 D ‐optimised planning results in improved tumour dose coverage compared with traditional points‐based planning methods and also improves dose to the rectum and bladder.