Open AccessLargely reduced OAR doses, and planning and delivery times for challenging robotic SBRT cases, obtained with a novel optimizer
Author(s) -
Giżyńska Marta K.,
Rossi Linda,
Toom Wilhelm,
Milder Maaike T. W.,
Vries Kim C.,
Nuyttens Joost,
Heijmen Ben J. M.
Publication year - 2021
Publication title -
journal of applied clinical medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.83
H-Index - 48
ISSN - 1526-9914
DOI - 10.1002/acm2.13172
Subject(s) - prostate , rectum , medicine , cyberknife , lung , radiation treatment planning , esophagus , prostatic urethra , urethra , urology , nuclear medicine , radiation therapy , radiology , surgery , radiosurgery , cancer
Recently, VOLO™ was introduced as a new optimizer for CyberKnife ® planning. In this study, we investigated possibilities to improve treatment plans for MLC‐based prostate SBRT with enhanced peripheral zone dose while sparing the urethra, and central lung tumors, compared to existing Sequential Optimization (SO). The primary focus was on reducing OAR doses. For 25 prostate and 25 lung patients treated with SO plans, replanning with VOLO™ was performed with the same planning constraints. For equal PTV coverage, almost all OAR plan parameters were improved with VOLO™. For prostate patients, mean rectum and bladder doses were reduced by 34.2% ( P < 0.001) and 23.5% ( P < 0.001), with reductions in D 0.03cc of 3.9%, 11.0% and 3.1% for rectum, mucosa and bladder (all P ≤ 0.01). Urethra D 5% and D 10% were 3.8% and 3.0% lower ( P ≤ 0.002). For lung patients, esophagus, main bronchus, trachea, and spinal cord D 0.03cc was reduced by 18.9%, 11.1%, 16.1%, and 13.2%, respectively (all P ≤ 0.01). Apart from the dosimetric advantages of VOLO™ planning, average reductions in MU, numbers of beams and nodes for prostate/lung were 48.7/32.8%, 26.5/7.9% and 13.4/7.9%, respectively ( P ≤ 0.003). VOLO™ also resulted in reduced delivery times with mean/max reductions of: 27/43% (prostate) and 15/41% (lung), P < 0.001. Planning times reduced from 6 h to 1.1 h and from 3 h to 1.7 h for prostate and lung, respectively. The new VOLO™ planning was highly superior to SO planning in terms of dosimetric plan quality, and planning and delivery times.