Universal Survival Curve and Single Fraction Equivalent Dose: Useful Tools in Understanding Potency of Ablative Radiotherapy

Park, Clint; Papież, Lech; Zhang, Shichuan; Story, Michael D.; Timmerman, Robert

doi:10.1016/j.ijrobp.2007.10.059

Cited by 581 publications

(417 citation statements)

References 23 publications

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“…13,14 A new radiobiological model called universal survival curve (USC) to compare different fractionations of both conventionally fractionated radiotherapy and SBRT was published in 2008. 15 This model was constructed to provide a superior approximation of the experimentally measured survival curve data in the high-dose range by hybridizing the LQ model survival curve for the low-dose range (the shoulder) and the multitarget model asymptote for high-dose range. According to the USC model, D T is the transition dose from LQ model to the multitarget model.…”

Section: Tumor Radiosensitivitymentioning

confidence: 99%

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Radiobiology of stereotactic body radiation therapy (SBRT)

Garau

2017

Reports of Practical Oncology & Radiotherapy

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a b s t r a c tRecent advances in the technology of radiotherapy have enabled the development of new therapeutic modalities that deliver radiation with very high accuracy, reduced margins and high dose conformation, allowing the reduction of healthy tissue irradiated and therefore minimizing the risk of toxicity. The next step was to increase the total tumor dose using conventional fractionation (which remains the best way to relatively radioprotect healthy tissues when large volumes are treated) or to use new fractionation schemes with greater biological effectiveness. Based on the experience gained in radiosurgery, the latter way was chosen for small and well-defined tumors in the body. Stereotactic body radiotherapy delivers high doses of radiation to small and well-defined targets in an extreme hypofractionated (and accelerated) scheme with a very high biological effectiveness obtaining very good initial clinical results in terms of local tumor control and acceptable rate of late complications.In fact, we realize a posteriori that it was not feasible to administer such biologically equivalent dose in a conventional fractionation because the treatment could last several months.So far, these new therapeutic modalities have been developed due to technologic advances in image guidance and treatment delivery but without a solid biological basis. It is the role of traditional radiobiology (and molecular radiobiology) to explain the effects of high doses of ionizing radiation on tumor and normal tissues. Only through a better understanding of how high doses of ionizing radiation act, clinicians will know exactly what we do, allowing us in the future to refine our treatments. This article attempts to describe through simple and understandable concepts the known aspects of the biological action of high doses of radiation on tumor and normal tissues, but it is clear that we need much more basic research to better understand the biology of high doses of radiation.

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Section: Tumor Radiosensitivitymentioning

confidence: 99%

“…The model fits very well with a cell survival curve of H460 NSCLC obtained by clonogenic assay. 15 The main weakness of the model is its dependence on five radiobiological parameters: ˛, ˇ, D 0 , D q and D T . Two examples of calculations are shown below.…”

Section: Tumor Radiosensitivitymentioning

confidence: 99%

Radiobiology of stereotactic body radiation therapy (SBRT)

Garau

2017

Reports of Practical Oncology & Radiotherapy

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“…There are significant uncertainties in the results, particularly as the linear quadratic model may require modification for large dose‐per‐fraction, as is the case in SBRT. ( 19 ) Further, in the absence of 4D dose calculation, the GTV and PTV in this study are different between CyberKnife and 3D CRT due to patient respiratory motion. In an effort to address the different dosemetric characteristics of linac‐based SBRT and that of CyberKnife for lung tumor treatment, we present a matched comparison of treatment plans for both modalities.…”

Section: Introductionmentioning

confidence: 74%

“…( 27 ) Therefore, single point metrics such as

{normalV}_{20}

, which is the percentage volume receiving the dose of 20 Gy or higher, may be used as a single factor to estimate lung complication for conventional lung treatment. However, lung toxicity from a dose of 20 Gy given in few fractions is not predicted by conventional models or metrics ( 19 ) and thus, it is unlikely that

{normalV}_{20}

can adequately represent the possibilities of lung complication of SBRT treatment. Lung toxicity following SBRT treatment is a subject of much discussion and interest.…”

Section: Resultsmentioning

confidence: 99%

A dosimetric comparison of stereotactic body radiation therapy techniques for lung cancer: robotic versus conventional linac‐based systems

Ding

Chang

Haslam

et al. 2010

J Applied Clin Med Phys

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The aim of this study is to compare the dosimetric characteristics of robotic and conventional linac‐based SBRT techniques for lung cancer, and to provide planning guidance for each modality. Eight patients who received linac‐based SBRT were retrospectively included in this study. A dose of 60 Gy given in three fractions was prescribed to each target. The Synchrony Respiratory Tracking System and a 4D dose calculation methodology were used for CyberKnife and linac‐based SBRT, respectively, to minimize respiratory impact on dose calculation. Identical image and contour sets were used for both modalities. While both modalities can provide satisfactory target dose coverage, the dose to GTV was more heterogeneous for CyberKnife than for linac planning/delivery in all cases. The dose to 1000 cc lung was well below institutional constraints for both modalities. In the high dose region, the lung dose depended on tumor size, and was similar between both modalities. In the low dose region, however, the quality of CyberKnife plans was dependent on tumor location. With anteriorly‐located tumors, the CyberKnife may deliver less dose to normal lung than linac techniques. Conversely, for posteriorly‐located tumors, CyberKnife delivery may result in higher doses to normal lung. In all cases studied, more monitor units were required for CyberKnife delivery for given prescription. Both conventional linacs and CyberKnife provide acceptable target dose coverage while sparing normal tissues. The results of this study provide a general guideline for patient and treatment modality selection based on dosimetric, tumor and normal tissue sparing considerations.PACS numbers: 87.53.Ly, 87.55.dk.

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“…Irradiation was delivered in 3 fractions over three consecutive days to total dose of 33 Gy in 11-Gy fractions to the 80% isodose line that encompassed the target volume. For comparison of single and multiple dose regimens, the radiation dose was converted to a biological equivalent dose (BED) [27] and a single fraction equivalent dose (SFED) [28] according to the formulas below, assuming an α/β ratio of 8.6 for tumor control, and where D is total dose, d is dose per fraction, and D q is 1.8:…”

Section: Radiation Techniquementioning

confidence: 99%