Assessment Of Organ Motion Research Articles

Narrative review of the utility of magnetic resonance imaging in radiotherapy for cervical cancer.

In radiotherapy (RT) for locally advanced cervical cancer, high soft tissue contrast on magnetic resonance imaging (MRI) can ensure accurate delineation of target volumes (TVs) and optimal dose distribution to the RT target and organs at risk (OAR). MRI-guided adaptive RT (MRIgART) is a novel technology that revises RT plans according to anatomical changes occurring throughout the treatment to improve target coverage and minimise OAR toxicity. This review aims to assess the evidence and gaps of MRI use in RT planning and MRIgART in the treatment of cervical cancer, as well as challenges in its clinical implementation. Ovid Medline and PubMed were searched using keywords for MRI in RT for cervical cancer. After applying the inclusion and exclusion criteria, the initial search was deduced to 32 studies. A total of 37 final studies were reviewed, including eight additional articles from references. In the primary studies, TVs and organ motion were assessed before, during, and after treatment. MRI was used to investigate dose distribution and therapeutic response to the treatment in association with its outcome. Lastly, rationales for MRIgART were evaluated. It was concluded that MRI enables accurate target delineation, assessment of organ motion and interfraction changes, and monitoring of treatment response through dynamic parameters. Enhanced target coverage and reduced OAR irradiation through MRIgART can improve local control and the overall outcome, although its rationales against the logistical challenges need to be evaluated on further research.

Assessment of Organ Motion in Postoperative Endometrial and Cervical Cancer Patients Treated With Intensity-Modulated Radiation Therapy

Intensity-modulated radiation therapy (IMRT) may be useful to reduce toxicity in gynecologic cancer patients requiring postoperative pelvic irradiation. This study was undertaken to quantify vaginal wall organ motion during the course of postoperative pelvic irradiation using pelvic IMRT. Twenty-two consecutive patients treated with postoperative pelvic IMRT on helical tomotherapy had fiducial markers placed at the vaginal apex prior to simulation then daily megavoltage computed tomography (CT) scans for positioning. The daily positions of the fiducials were registered and measured in reference to the initial CT scan to quantify the degree of vaginal wall organ motion during the entire course of therapy. The total motion of the fiducials center of mass (COM) was a median of 5.8 mm (range, 0.6-20.2 mm), and 95% of all COM positions fell within 15.7 mm of their original position. Directional margins of 3.1 mm along the right-left axis, 9.5 mm along the superoinferior axis, and of 12.1 mm along the anteroposterior axis encompassed the vaginal fiducials in 95% of treatments. Mean organ deformation for all patients was 3.9 mm, (range, 0-27.5 mm; standard deviation, 3.1 mm), with significant distortions of greater than 10 mm in 17% of secondary image sets. These data suggest a planning target volume margin of 16 mm will account for maximal organ motion in the majority of gynecologic patients undergoing postoperative pelvic IMRT, and it may be possible to incorporate directional motion into the planning target volume margin.

Assessment of Organ Motion in Intact Cervix Cancer Patients Treated with Intensity Modulated Radiation Therapy

Assessment of Organ Motion in Intact Cervix Cancer Patients Treated with Intensity Modulated Radiation Therapy

Poster — Thur Eve — 26: Cinical Implimentation of kV CBCT for Gynecological IMRT

The aim of this work was to implement CBCT imaging for assessment of CTV coverage for IMRT treatment of gynecological malignancies. A cone beam CT imaging protocol was developed to assist with assessment of organ motion and dose volume analysis. Accurate assessment of CBCT dosimetry using Monte Carlo simulations was performed to allow selection of a CBCT imaging protocol that was deemed to not elevate the risk of second malignancy as well as providing the opportunity to incorporate CBCT doses into the treatment plan. Assessment of CTV coverage was performed by contouring structures on multiple CBCT images for each patient. Dose volume calculations were performed on the CBCT data sets for the CTV segmented into vessel and vaginal regions, bladder and rectum. Measurements of bladder and rectal volumes, intra‐organ distance and marker seed positions are reported. Data was collected for patients treated between fall 2009 and spring 2010 using a seven field sliding window IMRT technique. It is concluded that routine CBCT imaging provides a safe and effective method of assessing the impact of organ motion for patients under going gynae IMRT. The posterior‐superior margin of the vaginal CTV may be impacted by bladder and rectal filling which should be accounted either through appropriate patient preparation protocols or by PTV margin adjustment. The feasibility of using fiducial markers for daily assessment of CTV coverage is the subject of ongoing investigation.

Assessment of Organ Motion in Postoperative Endometrial and Cervical Cancer Patients Treated with Intensity Modulated Radiation Therapy

Assessment of Organ Motion in Postoperative Endometrial and Cervical Cancer Patients Treated with Intensity Modulated Radiation Therapy

Assessment of organ motion using gated radiotherapy tools

Assessment of organ motion using gated radiotherapy tools