Influence of Treatment Technique on Dose-Volume Histogram and Normal Tissue Complication Probability for Small Bowel and Bladder A Prospective Study Using a 3-D Planning System and a Radiobiological Model in Patients Receiving Postoperative Pelvic Irradiation

Purpose. To develop normal tissue complication probability (NTCP) model with least absolute shrinkage and selection operator (LASSO) to analyze dose-volume effects that influence the incidence of acute diarrhea among gynecological patients with/without prior abdominal surgery.Methods and Materials. Ninety-five patients receiving gynecologic radiotherapy (RT) were enrolled. The endpoint was defined as the grade 2+acute diarrhea toxicity during treatment. We obtained the range of small-bowel volume in V4 Gy to V40 Gy of dose.Results. The number of patients experiencing grade 2+acute diarrhea toxicity was 23/61 (38%) in the group without abdominal surgery (group 0) and 17/34 (50%) patients with abdominal surgery (group 1). The most significant predictor was found for the logistic NTCP model with V16 Gy as the cutoff dose for group 0 and V40 Gy for group 1. Logistic regression NTCP model parameters were TV10≈ 290 cc for V16 Gy and TV10≈ 75 cc for V40 Gy, respectively.Conclusion. To keep the incidence of grade 2+acute small-bowel toxicity below 10%, we suggest that small-bowel volume above the prescription dose (V16 Gy) should be held to <290 cc for patients without abdominal surgery, and the prescription dose (V40 Gy) should be maintained <75 cc for patients with abdominal surgery.

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2067 Novel brachytherapy treatment planning system utilizing dose rate dependent average cell survival, CT-simulator, and dose-volume histogram

International Journal of Radiation Oncology*Biology*Physics ◽

10.1016/0360-3016(95)97969-8 ◽

1995 ◽

Vol 32 ◽

pp. 295

Author(s):

Rulon Mayer ◽

Wilson Fong ◽

Tanya Frankel ◽

Scott Simons ◽

Larry Kleinberg ◽

...

Keyword(s):

Cell Survival ◽

Dose Rate ◽

Treatment Planning ◽

Planning System ◽

Treatment Planning System ◽

Dose Volume Histogram ◽

Average Cell ◽

Rate Dependent ◽

Dose Volume

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Normal tissue tolerance dose for cervical radiotherapy to the NTCP model using a method of least square fit

Bayero Journal of Pure and Applied Sciences ◽

10.4314/bajopas.v12i1.34s ◽

2020 ◽

Vol 12 (1) ◽

pp. 215-220

Author(s):

E. Onuh ◽

A.S. Ajuji ◽

N. Rabiu ◽

M.S. Anas ◽

M. Jada

Keyword(s):

Normal Tissue ◽

Normal Tissue Complication Probability ◽

Least Square ◽

Planning System ◽

Radiotherapy Planning ◽

Treatment Planning System ◽

Normal Tissue Tolerance ◽

Tolerance Dose ◽

Method Of Least Square ◽

Least Square Fit

The purpose of this study is to evaluate the impact of Normal Tissue Complication Probability (NTCP) models on radiation treatment plans. We estimated NTCP parameters for the organs at risk (OARs) for cervical cancer radiotherapy. We pooled individual patient data from fifty patients who were treated with External Beam Radiotherapy technique between March 2012 and November 2013 in a part of Northern Nigeria with the exclusion of patients who had other gynaecological malignancies. Three basic methods were followed during the radiotherapy planning of these patients which included the pre-planning stage, planning radiotherapy treatment stage and treatment delivery. Various tests were carried out on these patients which helped to confirm the diagnosis after which they were treated using the linear accelerator, computed tomography simulator and the treatment planning system. We calculated the normal tissue tolerance doses for partial volumes of the organs using the values of the above –said parameters for published data on normal tissue tolerance doses. This article shows a graphical representation of the computed NTCP for left femur, right femur and skin presented and a fairly good correspondence is found between the curves for head of femurs and skin. Keywords: Normal Tissue Tolerance Dose, Normal Tissue Complication Probability, Method of Least Square Fit, Cervical Radiotherapy

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