Details

Autor(en) / Beteiligte

• Pogson, Elise M.
• Aruguman, Sankar
• Hansen, Christian R.
• Currie, Michael
• Oborn, Bradley M.
• Blake, Samuel J.
• Juresic, Josip
• Ochoa, Cesar
• Yakobi, Jim
• Haman, Alicia
• Trtovac, Admir
• Carolan, Martin
• Holloway, Lois
• Thwaites, David I.

Titel

Multi-institutional comparison of simulated treatment delivery errors in ssIMRT, manually planned VMAT and autoplan-VMAT plans for nasopharyngeal radiotherapy

Ist Teil von

• Physica medica, 2017-10, Vol.42, p.55-66

Ort / Verlag

Italy: Elsevier Ltd

Erscheinungsjahr

2017

Quelle

MEDLINE

Beschreibungen/Notizen

• [Display omitted] •Clinically significant error magnitudes were found for 3 institutions/techniques.•Collimator, gantry, MLC shift and MLC field size error impact was quantified.•Large dose variations from simulated errors increased with higher plan complexity.•Ap-VMAT resulted in greater complexity and dose variation than mp-VMAT plans.•Various error metric response trends were consistent over institutions/techniques. To quantify the impact of simulated errors for nasopharynx radiotherapy across multiple institutions and planning techniques (auto-plan generated Volumetric Modulated Arc Therapy (ap-VMAT), manually planned VMAT (mp-VMAT) and manually planned step and shoot Intensity Modulated Radiation Therapy (mp-ssIMRT)). Ten patients were retrospectively planned with VMAT according to three institution’s protocols. Within one institution two further treatment plans were generated using differing treatment planning techniques. This resulted in mp-ssIMRT, mp-VMAT, and ap-VMAT plans. Introduced treatment errors included Multi Leaf Collimator (MLC) shifts, MLC field size (MLCfs), gantry and collimator errors. A change of more than 5% in most selected dose metrics was considered to have potential clinical impact. The original patient plan total Monitor Units (MUs) were correlated to the total number of dose metrics exceeded. The impact of different errors was consistent, with ap-VMAT plans (two institutions) showing larger dose deviations than mp-VMAT created plans (one institution). Across all institutions’ VMAT plans the significant errors included; ±5° for the collimator angle, ±5mm for the MLC shift and +1, ±2 and ±5mm for the MLC field size. The total number of dose metrics exceeding tolerance was positively correlated to the VMAT total plan MUs (r=0.51, p<0.001), across all institutions and techniques. Differences in VMAT robustness to simulated errors across institutions occurred due to planning method differences. Whilst ap-VMAT was most sensitive to MLC errors, it also produced the best quality treatment plans. Mp-ssIMRT was most robust to errors. Higher VMAT treatment plan complexity led to less robust plans.