Methods of verifying the output of the treatment planning system used for high dose rate (HDR) prostate brachytherapy

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• 作者：Aaron Huckle ; ^{ah@medphysics.leeds.ac.uk} ; Bashar Al-Qaisieh ; Peter Bownes
• 关键词：AKS ; air kerma strength ; COIN ; conformal index ; EBRT ; external beam radiotherapy ; HDR ; high dose rate ; HWL ; height ; width and length measurements ; NTCP ; normal tissue complication probability ; PVE ; prostate volume estimate ; PTV ; planning target volume ; PT
• 刊名：Radiotherapy and Oncology
• 出版年：2012
• 期刊代码：231_01678140
• 类别：med
• 出版时间：May, 2012
• 卷：103
• 期：2
• 页码：261-265
• 文件大小：370 K

摘要

Objectives

To investigate the relationships between the planning target volume (PTV) and the total reference air kerma (TRAK) required to irradiate the prostate using the Nucletron microSelection ¹⁹²Ir radioactive stepping source afterloader for the treatment of prostate cancer.

Methods

Using 54 patient plans, the relationship between the treatment planning system (TPS) TRAK (TRAK_TPS) and the estimate and planimetry prostate volumes was investigated. Linear regression analysis was used to predict the TRAK (TRAK_pred) using the prostate gland height, width and length (HWL) measurements. The TRAK was corrected using a conformal index (COIN) of the plan to improve the accuracy of the model. A further 54 patient plans were then used to evaluate the outcome of the linear regression lines.

Results

A formula was proposed (HxWxLx蟺/5.19) to estimate the prostate volume, which showed a mean deviation from the planimetry volume of 0.0139 卤 3.339 cm³, where 69%was within 卤10%of planimetry, and 96%within 卤20%. Scatter graphs of TRAK_TPS for 54 plans, showed a positive linear correlation, r = 0.98, using the planimetry volume, and r = 0.95 for the estimated volume. The further 54 treatment plans used for evaluation showed the TRAK_pred was accurately predicted to 卤10%for 100%of plans using the planimetry volume and 81%using the prostate volume estimate.

Conclusions

The verification method proposed was found to be accurate and independent of TPS parameters, with suitable acceptance margins of 卤10%.