Radiation Physics

PV QA 3 - Poster Viewing Q&A 3

TU_14_3190 - Dosimetric Evaluation of Automated Single-isocenteric vs. Conventional Multi- isocenteric SRS Technique Using Dynamic Conformal Arcs for the Treatment of Multiple Brain Metastasis

Tuesday, October 23
1:00 PM - 2:30 PM
Location: Innovation Hub, Exhibit Hall 3

Dosimetric Evaluation of Automated Single-isocenteric vs. Conventional Multi- isocenteric SRS Technique Using Dynamic Conformal Arcs for the Treatment of Multiple Brain Metastasis
R. K. Badkul1, H. Jiang1, H. Saleh2, A. M. Chen1, and F. Wang1; 1Department of Radiation Oncology, University of Kansas School of Medicine, Kansas City, KS, 2Department of Radiation Oncology, University of Kansas Medical Center, Kansas City, KS

Purpose/Objective(s): Multi-isocenter dynamic conformal arc (MIDCA) SRS technique is commonly utilized to treat brain metastasis. Conventionally, individual isocenters are used to treat each lesion separately, which is time consuming and uncomfortable for the patients. An automated single isocenter dynamic conformal arc (SIDCA) technique to treat all lesions simultaneously could save machine time and help patient to tolerate the shorter treatment time. Our objective of this study is to analyze and compare the quality of treatment plans generated using single-isocenter vs multi-isocenter techniques employing non-coplanar dynamic conformal arcs .

Materials/Methods: Five multiple brain metastasis patients were selected for this study, who were treated with MIDCA on a treatment planning system. Number of brain lesions in each patient ranged from 3 to 10 and there were total 27 targets in all 5 patients. Prescribed doses ranged from 15 Gy to 20Gy depending on tumor volume and location. All patient’s contours were transferred to single isocenter automated multimets element software. Three to four non-coplanar arcs were used for each lesion in MIDCA plans whereas 5 non-coplanar arcs were used for each patient to treat all lesions in SIDCA plans. For dosimetric plan quality evaluation, conformity index (CI), volume of 12 Gy (V12) and volume of 5Gy ( V5) were collected for all the plans and compared.

Results: Average CI for SIDCA was 1.45 (SD 0.8) versus 1.63 (SD 0.2) for MIDCA. Average V12 for SIDCA 24.3cc (SD 23.3cc) versus 29.8 cc (SD 29.1cc) for MIDCA technique. As number of targets increases V5 and V12 dramatically increased for SIDCA technique, for 10 lesions plans V12 values were 65.7cc and 50.5cc for SIDCA and MIDCA respectively. Similarly, V5 values were 373cc and 272cc for SIDCA and MIDCA respectively. As expected Monitor units were significantly lower for SIDCA as compared to MIDCA hence shorter treatment delivery time.

Conclusion: Single isocenter plans done using automated multiments element software were better in conformity index however they were inferior in lower dose volumes such as 12 and 5 Gy. This difference was observed larger when number of brain lesions increased. Single isocenter technique is very convenient and time saving for treating multiple brain mets SRS, however, it could compromise lower dose conformity and potentially could deliver higher volumes of lower doses to normal brain tissue.

Author Disclosure: R.K. Badkul: None. H. Jiang: None. A.M. Chen: None. F. Wang: None.

Send Email for Rajeev Badkul


Assets

TU_14_3190 - Dosimetric Evaluation of Automated Single-isocenteric vs. Conventional Multi- isocenteric SRS Technique Using Dynamic Conformal Arcs for the Treatment of Multiple Brain Metastasis



Attendees who have favorited this

Please enter your access key

The asset you are trying to access is locked. Please enter your access key to unlock.

Send Email for Dosimetric Evaluation of Automated Single-isocenteric vs. Conventional Multi- isocenteric SRS Technique Using Dynamic Conformal Arcs for the Treatment of Multiple Brain Metastasis