Volume effects in the irradiated canine spinal cord: do they exist when the probability of injury is low?

Powers, Barbara E.; Thames, Howard D.; Gillette, S.M.; Smith, Cyndi D.; Beck, E; Gillette, Edward L.

doi:10.1016/s0167-8140(97)00213-2

Cited by 45 publications

(23 citation statements)

References 33 publications

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“…Thus, parotid glands lose function at a rate of approximately 5% per Gy. This coefficient yields a "threshold dose" (for 25% function, on average) of 25.8 Gy (in 35 fractions), which is consistent with Michigan's data (28 Gy, determined at 1-year follow-up), but lower than Roesnik et al's value (35)(36)(37)(38)(39). Figure 11 is clearly consistent with the 26 Gy threshold value: if both glands receive more than about 25-30 Gy, salivary flow is poor, whereas if both glands receive less (or even one gland receives significantly less), salivary flow is significantly higher.…”

Section: Xerostomia Due To Head and Neck Cancer Treatmentsupporting

confidence: 86%

See 1 more Smart Citation

Image-Based Modeling of Normal Tissue Complication Probability for Radiation Therapy

Deasy

Naqa

2008

Cancer Treatment and Research

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Radiation therapy dose distributions to eradicate tumor cells are typically constrained in extent or intensity to minimize the risk of injury to nearby critical normal tissues. With the widespread use of 3D image-based treatment planning systems, the question naturally arises how patient-specific anatomy and treatment differences affect outcome. It has long been known, that for many organs, variations in the fractional volume irradiated to high doses greatly alters the dose to achieve a given complication level (the "isoeffective dose") [1]. Smaller irradiated fractional volumes often lead to a much lower risk of complication; this is often referred to as the "volume-effect" in the literature, but would be more correctly referred to as the "dose-volume" effect. Normal tissue complication probability (NTCP) modeling is simply the ongoing effort to understand the risk of normal tissue injury as a function of the 3D dose distribution. Recently, there has been a steady accumulation of NTCP studies [2], and this is expected to continue or even accelerate in the future. NTCP models are particularly needed when the "volume-effect" becomes important (i.e., injury depends on the detailed dose distribution), such as for skin, lung, or liver. In this chapter we will review the basic principles of NTCP modeling, as well as publications related to selected endpoints (xerostomia, radiation pneumonitis, late rectal toxicity), and several issues related to the use of NTCP models, especially relating to their safe use. Other recent reviews which further discuss data on endpoints of interest in treatment planning include Deasy and Fowler [3], Moiseenko et al. [4], and the slightly older but still invaluable Seminars in Radiation Oncology issue, edited by Randy Ten Haken, devoted to dose-volume effects in normal tissues [2]. A useful review of models and model principles are the chapters by Jackson and Yorke [5], and Yorke [6]. Many technical issues in modeling dose-volume outcomes were also discussed by Deasy et al. [7].This chapter describes standard NTCP models as well as our own approach, which is more data-driven and image-based [8]. This contrasts with the more common approach of assuming the validity of a specific model and then attempting to fit the model parameters to a given data set. The term "image-based" indicates

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Section: Xerostomia Due To Head and Neck Cancer Treatmentsupporting

confidence: 86%

“…Powers et al observed that, in 4 cm irradiated sections of Beagle dog spinal cords, pathological lesions often did not result in observable symptoms [36]. In comparison, lesions resulting from longer field irradiation (20 cm), at the same dose level, were typically larger and symptomatic.…”

Section: The Concepts Of "Serial" and "Parallel" Tissue Dose-responsementioning

confidence: 99%

Image-Based Modeling of Normal Tissue Complication Probability for Radiation Therapy

Deasy

Naqa

2008

Cancer Treatment and Research

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“…3 of Powers et al (13) is practically independent of n, and the 95% confidence limits for t are wide (0, 38). This raises the question of what role is played by t in threshold-type cluster models, a role about which the data give little information, as shown by the wide confidence interval.…”

Section: Role Of Threshold In Cluster Modelsmentioning

confidence: 94%

“…To illustrate how cluster models might be fitted to data, we fitted a fixed-threshold 1D cluster model to the data of Powers et al (13) in which 4-cm and 20-cm segments of canine spinal cord were irradiated with a range of doses (see their Fig. 3).…”

Section: Analysis Of Experimental Data: Volume Effect In Irradiated Smentioning

confidence: 99%

Cluster models of dose–volume effects

Zhang

Tucker

Liu

et al. 2004

International Journal of Radiation Oncology*Biology*Physics

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“…However, dose-volume studies showed decreased radiation sensitivity of small irradiated volumes in rat spinal cord. Several dosevolume studies in rats (1)(2)(3), pigs (4), dogs (5), and monkeys (6) have been performed. The rat studies showed a steep increase in ED 50 if field lengths smaller than 8 mm were irradiated.…”

Section: Introductionmentioning

confidence: 99%