Ali I, Algan O, Thompson S, Sindhwani P, Ahmad S
Assistant Professor, Medical Physics, Department of Radiation Oncology, University of Oklahoma Health Sciences Center, Oklahoma City, U.S.A. Tel: 405-271-8290, Fax: 405-271-9240, E-mail:
Gulf J Oncolog. 2013 Jan;1(13):6-14.
To investigate enlargement of prostate volume by edema during brachytherapy seed implantation and develop a nomogram model to calculate air-kerma strength (AKS) required for implantation of the enlarged transient prostatic volume.
The prostate volume was measured prior and after seed implantation using trans-rectal ultrasound imaging in the operating room to obtain volume enlargement. A nomogram model was developed that calculates AKS required for implantation of the enlarged transient prostate volume with optimal dose coverage.
The measured prostate enlargement in this study was up to 60% of the initial volume. The effective prostatic volume enlargement was calculated for three isotopes: 125I, 103Pd and 131Cs. The effective volume enlargement for 125I implants was relatively small (< 10%) because of its long half-life. For 103Pd and 131Cs with short half-lives, additional AKS up to 20% and 30%, respectively, might be required to provide appropriate dose coverage of possible enlarged prostatic volumes.
Prostate volume enlargement should be considered to obtain optimal dose coverage particularly for short half-life isotopes such as 131Cs and 103Pd. The nomogram model developed in this work provides the AKS required for implants with a wide range of prostatic volume enlargements (5-100%) for three isotopes.
prostate brachytherapy; nomogram; air-kerma strength; edema; volume enlargement.
研究近距离放射治疗粒子植入过程中前列腺因水肿导致的体积增大情况，并建立一个列线图模型，以计算植入增大的瞬时前列腺体积所需的空气比释动能强度（AKS）。
在手术室中使用经直肠超声成像测量粒子植入前后的前列腺体积，以获得体积增大情况。建立了一个列线图模型，该模型可计算植入增大的瞬时前列腺体积并实现最佳剂量覆盖所需的AKS。
本研究中测量到的前列腺增大可达初始体积的60%。计算了三种同位素（125I、103Pd和131Cs）的有效前列腺体积增大情况。由于125I半衰期长，其植入后的有效体积增大相对较小（<10%）。对于半衰期短的103Pd和131Cs，可能分别需要高达20%和30%的额外AKS，以确保对可能增大的前列腺体积提供适当的剂量覆盖。
为获得最佳剂量覆盖，应考虑前列腺体积增大的情况，特别是对于半衰期短的同位素，如131Cs和103Pd。本研究建立的列线图模型提供了三种同位素在广泛的前列腺体积增大范围（5 - 100%）下植入所需的AKS。
前列腺近距离放射治疗；列线图；空气比释动能强度；水肿；体积增大
