Potential increase in biological effectiveness from field timing optimization for stereotactic body radiation therapy

Schmitt, Jonathan; Warren, Graham; Wang, Iris Z.

doi:10.1118/1.4709605

Cited by 4 publications

(3 citation statements)

References 27 publications

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“…It is therefore widely accepted that one approach to improve the efficacy of cancer therapy is the development of rational combinations of anticancer agents that may exhibit synergistic interactions. The introduction of several biologic agents represents an important advance in the management of NSCLC and some of them have shown to have a synergistic effect when given in combination with radiotherapy and chemotherapy in preclinical and clinical models (13)(14)(15). In the present review we discuss the rationale and the feasibility of these combinations and demonstrate the early results available from clinical trials using the BCBS units.…”

Section: Resultsmentioning

confidence: 95%

Outcome Study of Cobalt Based Stereotactic Body Radiation Therapy for Patients with Inoperable Stage III Non-small Cell Lung Cancer

Wang

Lan

Kang

et al. 2014

Technol Cancer Res Treat

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Aim of this paper is to retrospectively evaluate the efficacy and toxicity of specialized Body Cobalt based system (BCBS) treatment in the senior patients group (.65 years) with Stage III non-small cell lung carcinoma (NSCLC). A total of 49 patients (41 males and 8 females) with Stage III NSCLC according to UICC TNM classification (6(th) edition) were treated using OUR-QGD™ BCBS which was designed and manufactured in China. Post treatment evaluation with follow-up information was collected from April 2001 to December 2006 in our department. Median age of enrolled patients was 71 years old (65-85). Among those patients, 36 patients were pathologically identified with squamous cell carcinoma, and the other 13 patients were confirmed as adenocarcinoma. All patients were immobilized by vacuum based immobilization mold and then performed slow CT scan without any respiration gating devices. The daily radiation prescription dose was defined at 50% isodose line covering primary lesions and metastatic lymph nodes with doses from 2.5 to 6 Gy in 5 fractions per week according to the tumor stage and internally approved treatment protocols by the Institutional Review Board (IRB). Median daily dose and total delivery dose of 50% isodose line were 4 Gy and 41 Gy, respectively. In this study group, total of 3 patients received neoadjuvant cisplatin-based chemotherapy. Tumor response evaluated 12 weeks after radiation has demonstrated 13 complete responses (26.5%), 21 partial responses (42.9%). The overall survival (OS) rate of 1-year, 2-year and 3-year was 63.3%, 40.8% and 20.4%, respectively. The median and mean survival time was 22 and 24 months. All 49 patients tolerated the treatment well and have completed the planned therapy regiment. Body Cobalt based system treatment of those over 65 years old patients with Stage III NSCLC had reasonable and superior curative effect as well as local control, and at the same time without severe radiation side effects.

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Section: Resultsmentioning

confidence: 95%

Outcome Study of Cobalt Based Stereotactic Body Radiation Therapy for Patients with Inoperable Stage III Non-small Cell Lung Cancer

Wang

Lan

Kang

et al. 2014

Technol Cancer Res Treat

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“…Repair half-times of up to 154 min have been found by Amdur et al (1994) for the normal cell line AG1522 and 31 min with HTB-35 uterine-cervical cancer cell line. Schmitt et al (2012) quote a repair half time for normal lung tissue as long as 4 h and used repair halftimes for the lung cancer cell line NCI-H460 of 15 and 90 min. Since we included both normal and cancer cell lines in our study, our repair constant of 5.9 min is likely to be an underestimate of the repair half-time.…”

Section: Discussionmentioning

confidence: 99%

Imaging dose affects in vitro survival following subsequent therapeutic irradiation

Rogers

Suchowerska

Ralston

et al. 2015

Biomed. Phys. Eng. Express

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The aim of this study is to determine whether the additional dose from imaging procedures such as four-dimensional computed tomography (4DCT) and cone beam computed tomography (CBCT) affect cell survival when followed by therapeutic radiation. A clonogenic assay was used for one human normal (human umbilical vein endothelial cell) and two cancer (NCI-H460 and MM576) cell lines. Each cell line was exposed to a kilovoltage 4DCT or CBCT imaging dose prior to therapeutic doses of 0, 2 and 4 Gy. The time interval between imaging and therapy was 8 h (4DCT) and 6 min (CBCT). To increase the statistical power of the analysis, the results were combined and the effects of the imaging dose tested for significance. The survival fraction was compared with the predictions of the Lea-Catcheside linear-quadratic (LQ) model with repair. The observations show that a CBCT dose (0.6 cGy) with no therapeutic dose caused an increase in survival for NCI-H460, however this effect was marginally significant. The pooled data showed that a 4DCT dose (14 cGy) caused a significant decrease in survival (p=0.0017) when followed by a 2 Gy therapeutic dose. This effect was larger than the theoretical prediction of the LQ model. Our results suggest two opposing low dose radiation effects: an increase in survival (hormesis) imparted by the smallest imaging doses and a decrease in survival (hypersensitivity) imparted by the larger imaging doses. The LQ model was a poor predictor of survival for small doses. The prime novelty of this work is the finding that 4DCT imaging can affect cell survival after a subsequent therapeutic dose. This study identifies the potential to increase the therapeutic ratio by using the imaging dose as a priming low dose partial fraction. Nomenclature CBCT cone beam computed tomography 4DCT four-dimensional computed tomography IGRT image-guided radiotherapy kV kilovoltage MV megavoltage LQ linear-quadratic model

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“…Taken from the literature, repair half-times of 16, 90 and 130 min were used for DU-145, H460 and AGO-1552b cells, respectively. 21,27,28 The calculated values were incorporated into the linear quadratic model to calculate the corresponding surviving fractions. The instant effect was also calculated using the formula: surviving fraction5e…”

Section: Theoretical Datamentioning

confidence: 99%

Investigation into the radiobiological consequences of pre-treatment verification imaging with megavoltage X-rays in radiotherapy

Hyland

McMahon²,

Butterworth³

et al. 2014

BJR

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Potential increase in biological effectiveness from field timing optimization for stereotactic body radiation therapy

Abstract: Rearranging field timing for a SBRT treatment so that maximal dose is deposited in the central fields of treatment may optimize cell kill and potentially affect overall treatment outcome.

Cited by 4 publications

References 27 publications

Outcome Study of Cobalt Based Stereotactic Body Radiation Therapy for Patients with Inoperable Stage III Non-small Cell Lung Cancer

Outcome Study of Cobalt Based Stereotactic Body Radiation Therapy for Patients with Inoperable Stage III Non-small Cell Lung Cancer

Imaging dose affects in vitro survival following subsequent therapeutic irradiation

Investigation into the radiobiological consequences of pre-treatment verification imaging with megavoltage X-rays in radiotherapy

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