International Journal of

Radiation Oncology biology

physics

www.redjournal.org

COMMENTS We Need Better Figures! In Regard to Lee To the Editor: I read with interest Dr Lee’s letter (1) calling for more consistent labeling of survival curves and Dr Zietman’s response that the International Journal of Radiation Oncology, Biology, Physics (the Red Journal) will be undertaking a review of standards for submission of figures. One area that I hope the editorial team will consider for standardization is the display of dose distributions and dose-volume histograms. There are potential biases in terms of interpretation of such figures, depending on, for example, dose levels selected and critical organ and target contours included (Fig. 1). In addition, especially when planning systems are compared, aesthetic issues like colors selected, dose washes versus contour lines, and overall “attractiveness” of the display could play a factor in terms of biasing interpretations in comparing different plans. Even the display mode of simple “1D” statistics has been shown to influence medical decision making (2).

In my opinion, it would be a progressive step if, as part of the production processes, authors of accepted articles were required to submit source data (ie, dose-volume matrices, Digital Imaging and Communications in Medicine radiation therapy structure data) that could then be processed through a standardized radiation therapy platform like CERR [Computational Environment for Radiotherapy Research] (3). This would allow generation of figures with a standardized set of dose displays settings (ie, consistent set of dose levels, colors, uniform appearance using contours or dose washes). This, coupled with a requirement for standards of organ-at-risk inclusion and target volume labeling would help eliminate or at least minimize potential biases due to variations in the display of visual dose information. The dose information could also be stored online as supplementary information and would be akin to submitting genomic data for basic science articles and allow for independent exploration/analysis of the data. The Red Journal’s commitment to improving the quality of figures is welcome, and consideration of standardizing dose distribution and dose-volume histogram illustrations as important components of our discipline’s scholarly work could be a helpful component of this initiative.

Fig. 1. An example of intraetreatment planning system display variations within a treatment planning system. Variation in opacity of dose wash display and the isodose levels selected for display creates perception that the distribution on the left is more conformal. Int J Radiation Oncol Biol Phys, Vol. 88, No. 5, pp. 1212e1214, 2014 0022-3476/$ - see front matter Ó 2014 Elsevier Inc. All rights reserved.

Comments 1213

Volume 88  Number 5  2014 Glenn Bauman, MD, FRCPC Department of Oncology London Regional Cancer Program/London Health Sciences Centre and Western University London, Ontario, Canada http://dx.doi.org/10.1016/j.ijrobp.2014.01.003

References 1. Lee WR. We need better figures!. Int J Radiat Oncol Biol Phys 2014;88:236. 2. Marshall T, Mohammed MA, Rouse A. A randomized controlled trial of league tables and control charts as aids to health service decisionmaking. Int J Qual Health Care 2004;16:309-315. 3. Deasy et al. A Computational Environment for Radiotherapy Research. Available at http://www.cerr.info/about.php. Accessed February 1, 2014.

In Reply to Bauman The editorial board of the Red Journal is very grateful to Dr Bauman for his wise suggestions to Dr Lee’s comments (1, 2). At present, we are not resourced to gather data and generate curves, dose-volume histograms, and other illustrations in a standardized fashion as some other journals can, but we agree that this should be prioritized as a goal. Although we may not be able to achieve this in a single step, we will begin to discuss creative ways to make this happen. Anthony L. Zietman, MD Editor-in-Chief Department of Radiation Oncology Massachusetts General Hospital Boston, Massachusetts http://dx.doi.org/10.1016/j.ijrobp.2014.01.004

References 1. Bauman G. In regard to Lee. Int J Radiat Oncol Biol Phys 2014;88: 1212-1213. 2. Lee WR. We need better figures!. Int J Radiat OncolBiolPhys 2014;88: 236.

departments or with the use of different radiation therapy equipment. In their report, in nearly all cases in which the cumulative delivered mean parotid dose decreased compared with the planned dose, the other parotid gland in the same patient showed an increase compared with the planned dose. We also studied the actual dose to the parotid glands in intensity modulated radiation therapy. With helical tomotherapy, patients with nasopharyngeal carcinoma were scanned by megavoltage computed tomography (MVCT) before each treatment in our department. Variations of the mean dose of 2 parotids in the same patient were positively correlated (PZ.05, rZ0.553). The difference between actual and planned dose was positively correlated with the difference of parotid volume (PZ.024, rZ0.442), and this was more obvious during the course of treatment (rZ 0.95) (2). Hence, the change in the parotid volume may be the main reason leading to dose changes. We gathered weekly MVCT images before treatment. The median change of the absolute parotid volume was 7.53 cc, and the median change of the relative volume was 27.7% in the last treatment. The change of parotid volume was larger in our study than in that in the report of Hunter et al. The dose difference measured in phantom between kilovoltage CT and MVCT planning was less than 2% in our department. However, to reduce interference, we evaluated the difference between the cumulative parotid dose based on the first treatment and the total cumulative delivered dose. At the same time, we partially eliminated setup errors that might be difficult to eliminate. We found that the median dose of Dmean difference was 0.66 Gy, suggesting that dose difference was not obvious in most patients, but there were still 30.7% (8/26) patients whose parotid Dmean difference was higher than 4 Gy. Therefore, these patients were more suitable for adaptive radiation therapy (ART). Fixation technique and image guidance technology can eliminate most of the setup errors. Although translational setup corrections can not completely eliminate rotational setup errors, the impact of these errors still needs to be evaluated. In terms of the difference between our data and the report by Hunter et al, differences in treatment equipment and quality assurance may be the main reasons.

Parotid glands dose-effect relationships based on their actually delivered doses: Implications for adaptive replanning in radiation therapy of head-and-neck cancer

Gang Ren, MD Lin Ma, MD, PhD Shouping Xu, PhD Department of Radiation Oncology Chinese PLA General Hospital Beijing, China

In Regard to Hunter et al To the Editor: We read the study by Hunter and colleagues (1) with great interest. They thought that the residual setup error was still large enough to cause the dosimetric deviation after translational setup corrections by cone beam computed tomographic image guided radiation therapy. However, they did not give details of the rotation error in their article. In fact, the deviation may be different in other

http://dx.doi.org/10.1016/j.ijrobp.2014.01.025

References 1. Hunter KU, Fernandes LL, Vineberg KA, et al. Parotid glands dose-effect relationships based on their actually delivered doses: Implications for adaptive replanning in radiation therapy of

We need better figures! In regard to Lee.

We need better figures! In regard to Lee. - PDF Download Free
587KB Sizes 1 Downloads 3 Views