Open AccessEPID ‐based in vivo dosimetry using Dosimetry Check™: Overview and clinical experience in a 5‐yr study including breast, lung, prostate, and head and neck cancer patients
Author(s) -
Nailon William H.,
Welsh Daniel,
McDonald Kim,
Burns Donna,
Forsyth Julie,
Cooke Gillian,
Cutanda Francisco,
Carruthers Linda J.,
McLaren Duncan B.,
Puxeu Vaqué Josep,
Kehoe Terence,
Andiappa Sankar
Publication year - 2019
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/acm2.12441
Subject(s) - dosimetry , medicine , prostate , nuclear medicine , radiation therapy , prostate cancer , breast cancer , radiation treatment planning , imaging phantom , cancer , radiology
Background Independent verification of the dose delivered by complex radiotherapy can be performed by electronic portal imaging device ( EPID ) dosimetry. This paper presents 5‐yr EPID in vivo dosimetry ( IVD ) data obtained using the Dosimetry Check ( DC ) software on a large cohort including breast, lung, prostate, and head and neck (H&N) cancer patients. Material and Methods The difference between in vivo dose measurements obtained by DC and point doses calculated by the Eclipse treatment planning system was obtained on 3795 radiotherapy patients treated with volumetric modulated arc therapy ( VMAT ) ( n = 842) and three‐dimensional conformal radiotherapy (3 DCRT ) ( n = 2953) at 6, 10, and 15 MV. In cases where the dose difference exceeded ±10% further inspection and additional phantom measurements were performed. Results The mean and standard deviation ( μ ± σ ) of the percentage difference in dose obtained by DC and calculated by Eclipse in VMAT was: 0.19 ± 3.89 % in brain, 1.54 ± 4.87 % in H&N, and 1.23 ± 4.61 % in prostate cancer. In 3 DCRT , this was 1.79 ± 3.51 % in brain, − 2.95 ± 5.67 % in breast, − 1.43 ± 4.38 % in bladder, 1.66 ± 4.77 % in H&N, 2.60 ± 5.35% in lung and − 3.62 ± 4.00 % in prostate cancer. A total of 153 plans exceeded the ±10% alert criteria, which included: 88 breast plans accounting for 7.9% of all breast treatments; 28 H&N plans accounting for 4.4% of all H&N treatments; and 12 prostate plans accounting for 3.5% of all prostate treatments. All deviations were found to be as a result of patient‐related anatomical deviations and not from procedural errors. Conclusions This preliminary data shows that EPID ‐based IVD with DC may not only be useful in detecting errors but has the potential to be used to establish site‐specific dose action levels. The approach is straightforward and has been implemented as a radiographer‐led service with no disruption to the patient and no impact on treatment time.