Open AccessOn correlations in IMRT planning aims
Author(s) -
Roy Arkajyoti,
Das Indra J.,
Nohadani Omid
Publication year - 2016
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 - 10.1120/jacmp.v17i6.6411
Subject(s) - interquartile range , correlation , medicine , mathematics , nuclear medicine , range (aeronautics) , statistics , materials science , geometry , composite material
The purpose was to study correlations amongst IMRT DVH evaluation points and how their relaxation impacts the overall plan. 100 head‐and‐neck cancer cases, using the Eclipse treatment planning system with the same protocol, are statistically analyzed for PTV, brainstem, and spinal cord. To measure variations amongst the plans, we use (i) interquartile range (IQR) of volume as a function of dose, (ii) interquartile range of dose as a function of volume, and (iii) dose falloff. To determine correlations for institutional and ICRU goals, conditional probabilities and medians are computed. We observe that most plans exceed the median PTV dose (averageD 50 = 104 % prescribed dose). Furthermore, satisfyingD 50reduced the probability of also satisfyingD 98, constituting a negative correlation of these goals. On the other hand, satisfyingD 50increased the probability of satisfyingD 2, suggesting a positive correlation. A positive correlation is also observed between the PTVV 105andV 110. Similarly, a positive correlation between the brainstemV 45andV 50is measured by an increase in the conditional median ofV 45, whenV 50is violated. Despite the imposed institutional and international recommendations, significant variations amongst DVH points can occur. Even though DVH aims are evaluated independently, sizable correlations amongst them are possible, indicating that some goals cannot be satisfied concurrently, calling for unbiased plan criteria. PACS number(s): 87.55.dk, 87.53.Bn, 87.55.Qr, 87.55.de.