Background
Medical decisions made by oncology clinicians have serious implications, even when made collaboratively with the patient. Clinicians often use the Eastern Clinical Oncology Group (ECOG) performance status (PS) scores to help them make treatment-related decisions.
Methods
The current study explores the variability of the ECOG score when applied to 12 predetermined specially designed clinical case vignettes presented to a group of oncology clinicians (
n
= 72). The quantitative analysis included evaluation of variability of ECOG PS scores and exploration of rater and patient-related factors which may influence the final ECOG rating. In-depth interviews were conducted with oncology clinicians to ascertain factors that they felt were important while making treatment-related decisions. Basic and global themes were generated following qualitative data analysis.
Results
Quantitative results showed that there was poor agreement in ECOG rating between raters. Overall concordance with the gold standard rating ranged between 19.4% and 56.9% for the vignettes. Moreover, patients deemed to have socially desirable qualities (
p
< 0.004) were rated to have better PS and women patients (
p
< 0.004) to have worse PS. Clinicians having international work experience had increased concordance with ECOG PS rating. Qualitative results showed that ‘perceived socio-economic background of the patient’, ‘age of the patient’, ‘patient’s and family’s preferences’ and ‘past treatment response’ were the major themes highlighted by respondents that influenced the treatment-related decisions made by clinicians.
Conclusion
There is considerable variability in ECOG PS determined by clinicians. Decision-making in oncology is complex, multifactorial and is influenced by rater and patient-related factors.
Kilovoltage cone-beam CT (kV CBCT) can be acquired during the delivery of volumetric modulated arc therapy (VMAT), in order to obtain an image of the patient during treatment. However, the quality of such CBCTs is degraded by megavoltage (MV) scatter from the treatment beam onto the imaging panel. The objective of this paper is to introduce a novel MV scatter correction method for simultaneous CBCT during VMAT, and to investigate its effectiveness when compared to other techniques. The correction requires the acquisition of a separate set of images taken during VMAT delivery, while the kV beam is off. These images--which contain only the MV scatter contribution on the imaging panel--are then used to correct the corresponding kV/MV projections. To test this method, CBCTs were taken of an image quality phantom during VMAT delivery and measurements of contrast to noise ratio were made. Additionally, the correction was applied to the datasets of three VMAT prostate patients, who also received simultaneous CBCTs. The clinical image quality was assessed using a validated scoring system, comparing standard CBCTs to the uncorrected simultaneous CBCTs and a variety of correction methods. Results show that the correction is able to recover some of the low and high-contrast signal to noise ratio lost due to MV scatter. From the patient study, the corrected CBCT scored significantly higher than the uncorrected images in terms of the ability to identify the boundary between the prostate and surrounding soft tissue. In summary, a simple MV scatter correction method has been developed and, using both phantom and patient data, is shown to improve the image quality of simultaneous CBCTs taken during VMAT delivery.
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