Al-Qaisieh Bashar, Brearley Elizabeth, St Clair Shaun, Flynn Anthony
Medical Physics Department, Cookridge Hospital, Leeds, UK.
Int J Radiat Oncol Biol Phys. 2006 May 1;65(1):304-7. doi: 10.1016/j.ijrobp.2005.12.030.
Prediction of the number of iodine seeds (I-125) required for prostate implantation is an important tool to reduce the number of unused seeds for brachytherapy. This study was designed to investigate the relationship between the number of seeds implanted vs. prostate volume. This can produce a tool to accurately estimate the number of seeds required for a given target volume. In addition, total cost of treatment, personal radiation risks during storage and handling, and errors in accounting for seeds can be reduced.
Data from two groups of patients who had I-125 seed prostate implants (Oncura/Amersham RAPIDStrand model 6711 I-125) have been separately analyzed: (A) The relationship between prostate volume vs. number of seeds implanted was based on 401 patients treated between 1999 and 2002 who were implanted with seeds of air kerma strength (AKS) of 0.459 microGy h(-1) @ 1 m per seed. (B) The relationship between prostate volume vs. total seed AKS was analyzed. This was based on 628 patients treated between 1999 and 2002 who were implanted with a range of seed strengths from 0.381 to 0.521 U. Both patient groups were subdivided into integer prostate volume bins. For each bin, the mean and 95% confidence intervals (CI) for the implanted number of seeds or total AKS implanted were calculated. The upper 95% CI was used to investigate the relationship between the number of seeds implanted and total AKS implanted vs. prostate volume.
The new method of predicting the number of seeds shows valid and accurate results. The required number of seeds can be predicted, which helps to reduce the number of leftover seeds to 3% of the total number of seeds ordered.
The number of I-125 seeds or the total activity that is required to deliver the prescribed dose for the target volume can be predicted. This could reduce the overall treatment cost by accurate seed ordering before implantation.
预测前列腺植入所需碘籽源（I - 125）的数量是减少近距离放射治疗中未使用籽源数量的重要手段。本研究旨在调查植入籽源数量与前列腺体积之间的关系。这可以产生一种工具，用于准确估计给定靶体积所需的籽源数量。此外，还可降低治疗总成本、储存和处理过程中的个人辐射风险以及籽源计数误差。
对两组接受I - 125籽源前列腺植入（Oncura/Amersham RAPIDStrand 6711型I - 125）的患者数据进行了单独分析：（A）前列腺体积与植入籽源数量之间的关系基于1999年至2002年期间接受治疗的401例患者，这些患者植入的籽源空气比释动能强度（AKS）为每颗籽源在1米处0.459微戈瑞·小时⁻¹。（B）分析了前列腺体积与籽源总AKS之间的关系。这基于1999年至2002年期间接受治疗的628例患者，这些患者植入的籽源强度范围为0.381至0.521单位。两组患者均被细分为整数前列腺体积区间。对于每个区间，计算植入籽源数量或植入总AKS的平均值和95%置信区间（CI）。使用95%置信区间上限来研究植入籽源数量和植入总AKS与前列腺体积之间的关系。
预测籽源数量的新方法显示出有效且准确的结果。可以预测所需的籽源数量，这有助于将剩余籽源数量减少至订购籽源总数的3%。
可以预测为靶体积提供规定剂量所需的I - 125籽源数量或总活度。这可以通过植入前准确订购籽源来降低总体治疗成本。
