ISSN: 1449-1907International Journal of Medical Sciences
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Int J Med Sci 2008; 5(1):41-49. doi:10.7150/ijms.5.41 This issue Cite
Research Paper
Qualitative Dosimetric and Radiobiological Evaluation of High – Dose – Rate Interstitial brachytherapy Implants
1. Department of Radiation Oncology, University of Pittsburgh Cancer Institute, Pittsburgh, PA, USA.
2. Department of Radiation Oncology, Case Western Reserve University, Cleveland, OH, USA
3. Department of Radiation Oncology, MD Oswal Memorial Cancer treatment and Research Center, Ludhiana (Pb), India.
Abstract
Radiation quality indices (QI), tumor control probability (TCP), and normal tissue complication probability(NTCP) were evaluated for ideal single and double plane HDR interstitial implants. In the analysis, geometrically–optimized at volume (GOV) treatment plans were generated for different values of inter–source–spacing (ISS) within the catheter, inter–catheter–spacing (ICS), and inter–plane–spacing (IPS) for single - and double - plane implants. The dose volume histograms (DVH) were generated for each plan, and the coverage volumes of 100%, 150%, and 200% were obtained to calculate QIs, TCP, and NTCP. Formulae for biologically effective equivalent uniform dose (BEEUD), for tumor and normal tissues, were derived to calculate TCP and NTCP. Optimal values of QIs, except external volume index (EI), and TCP were obtained at ISS = 1.0 cm, and ICS = 1.0 cm, for single–plane implants, and ISS = 1.0 cm, ICS = 1.0 cm, and IPS = 0.75 to 1.25 cm, for double – plane implants. From this study, it is assessed that ISS = 1.0 cm, ICS = 1.0 cm, for single - plane implant and IPS between 0.75 cm to 1.25 cm provide better dose conformity and uniformity.
Keywords: HDR interstitial implants, quality indices, inter-source-spacing, inter-catheter-spacing, geometrical – optimization at volume, biologically effective equivalent uniform dose.
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