Monash University
PhD student

Tim Dwyer
Monash University

Kim Marriott
Monash University

Jeremy Millar
The Alfred Hospital

Annette Haworth
The University of Sydney

Background and Purpose

As an alternative to the whole gland treatments, focal therapy aims to destroy the tumour cells while minimising damage to surrendering healthy tissues and structures. A biologically based model — tumour control probability (TCP) is used to relatively measure the quality of a focal plan. There is no general way of how biologically-based focal planning should be done. Using inverse planning techniques to create focal plans with appropriately applied objectives and constraints is promising. But this technique is not widely used in seed brachytherapy at the moment. Introducing interaction into the inverse planning technique to provide clinicians with greater controls over the optimisation process is proposed.


Achieving theoretically high rates of tumour control while maintaining low dose of radiation to both the urethra and rectum is possible with an inverse planning technique using a focal LDR brachytherapy approach [1]. In this study, we focus on using interactive inverse planning technique to answer the following questions:

(1).What should a clinically sound focal plan look like?

(2).What kind of user interactions and visualisations are required to facilitate clinicians in creating and evaluating biologically-based focal plans for prostate cancer?


An interactive web interface has been developed. it can produce focal treatment plans using different optimisation search strategies. It also provides users with interactive controls over the optimisation process, such as pausing the optimisation and adjust needle positions, locking existing needles and re-optimise. Produced treatment plans can be compared in real time to facilitate selecting the preferred treatment plan. Currently, a two-stage semi-conducted interview with the clinical community is undergoing. Future developments will provide greater control and improved display tools according to the feedback from the conducted interviews.


The optimal approach to focal brachytherapy planning is yet to be established. Even though focal treatment plans can be produced using inverse planning in a short period of time, using interactive inverse planning to produce better and more personalised focal treatment plans is the next step. However discussions and experiments are required to clarify how to help clinicians to better understand how to produce focal plans and also how to use interactive inverse planning effectively to support users in using experience and knowledge for focal plan creation and evaluation.


[1].Haworth, Annette, et al. "A radiobiology-based inverse treatment planning method for optimisation of permanent l-125 prostate implants in focal brachytherapy." Physics in medicine and biology 61.1 (2015): 430.

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