Commissioning of a 3D image‐based treatment planning system for high‐dose‐rate brachytherapy of cervical cancer

Abstract

The objective of this work is to present commissioning procedures to clinically implement a three‐dimensional (3D), image‐based, treatment‐planning system (TPS) for high‐dose‐rate (HDR) brachytherapy (BT) for gynecological (GYN) cancer. The physical dimensions of the GYN applicators and their values in the virtual applicator library were varied by 0.4 mm of their nominal values. Reconstruction uncertainties of the titanium tandem and ovoids (T&O) were less than 0.4 mm on CT phantom studies and on average between 0.8‐1.0 mm on MRI when compared with X‐rays. In‐house software, HDRCalculator, was developed to check HDR plan parameters such as independently verifying active tandem or cylinder probe length and ovoid or cylinder size, source calibration and treatment date, and differences between average Point A dose and prescription dose. Dose‐volume histograms were validated using another independent TPS. Comprehensive procedures to commission volume optimization algorithms and process in 3D image‐based planning were presented. For the difference between line and volume optimizations, the average absolute differences as a percentage were 1.4% for total reference air KERMA (TRAK) and 1.1% for Point A dose. Volume optimization consistency tests between versions resulted in average absolute differences in 0.2% for TRAK and 0.9 s (0.2%) for total treatment time. The data revealed that the optimizer should run for at least 1 min in order to avoid more than 0.6% dwell time changes. For clinical GYN T&O cases, three different volume optimization techniques (graphical optimization, pure inverse planning, and hybrid inverse optimization) were investigated by comparing them against a conventional Point A technique. End‐to‐end testing was performed using a T&O phantom to ensure no errors or inconsistencies occurred from imaging through to planning and delivery. The proposed commissioning procedures provide a clinically safe implementation technique for 3D image‐based TPS for HDR BT for GYN cancer.PACS number(s): 87.55.D‐

Does the apex optimization line matter for single‐channel vaginal cylinder brachytherapy planning?

“…Clinicians must validate the dimensions of the 3D‐modeled applicator library before clinical use, especially when a new version of an applicator is released without a corresponding update to the applicator library. As an example of the type of errors found on 3D‐modeled applicator libraries, Kim et al . found that the right ovoids of a titanium Fletcher‐Suit‐Delclos‐style tandem‐and‐ovoids set incorrectly matched with the left ovoids in the provided 3D‐modeled applicator library.…”

Dosimetric analysis of rib interference of the CTV during interstitial brachytherapy of lung tumors

“…Although several treatment options exist for the treatment of lung tumors with radiation, interstitial brachytherapy offers some advantage when considering tumor motion. Some radiologists [ 11 , 12 ] have pursued interstitial brachytherapy for managing tumor motion due to respiration during treatment [ 13 , 14 ], and with the help of 3D treatment planning software, it has become simple and practical to deliver highly conformal dose distributions to the target with brachytherapy [ 15 ].…”

Review of strategies for MRI based reconstruction of endocavitary and interstitial applicators in brachytherapy of cervical cancer

“…The susceptibility artifacts induced by titanium applicators make the reconstruction process difficult when it is based on MRI exclusively, especially at the tip end of the applicator or needles. 35,37,46,62,68 Susceptibility artifacts are position and sequence dependent, and may lead to low reconstruction accuracy, which can be improved by means of an additional CT scan. 69 Kim et al 37 evaluate the artifacts and distortions produced by tandem and ring and tandem and ovoids in 3 T MRI, finding the T1W sequence favorable in terms of size of the artifacts present in the images.…”