Aim

The conventional approach to radiotherapy planning is to prescribe a homogeneous dose to a target. However, for a tumor with a spatial variation in radiosensitivity, a uniform dose distribution is not optimal for maximizing the tumor control probability. Irradiating the most radioresistant regions to a higher dose will improve the overall probability of controlling the tumor (captured in the dose-response relationship). It is hypothesized that multi-parametric imaging and automated image understanding can provide a surrogate for the radioresistant regions, and this will be exploited in DR THERAPAT to come to an individualized dose prescription.

Approach

Biological models will be used to optimize tumor control probability (TCP) and minimize normal tissue complication probability (NTCP). The biological modeling will be based on functional imaging as validated with histology. The overall aim is to establish a digital dose representation for each patient which can be used to tailor optimized and individualized radiation therapy, addressing both prostate and cervical cancer.
For the normal tissue modeling, the objective is to explore how MRI can contribute to quantification and better understanding of normal tissue function of the rectum and bladder, the two most important organs at risk in irradiation of both prostate and cervical cancer. Focusing on a series of prostate cancer patients, we will investigate i) the changes in biomechanical properties of the rectum and bladder during treatment, also as function of accumulated doses and volumes, ii) the pattern of motion of the rectum and bladder, and their relations, and iii) the variation in pattern of organ motion in patients according to the observed biomechanical properties.

Expected outcome

DR THERAPAT will utilize tumor tissue classifications derived from multi-parametric imaging and automated image understanding to tailor non-homogenous dose distribution specific to the patient. Specific tumor response models will be developed for prostate and cervix cancer patients.
DR THERAPAT will integrate a comprehensive biomechanical characterization based on functional imaging with MRI for rectum and bladder to capture nonuniformity of organ function and allow better normal tissue response modeling, for prostate as well as cervix cancer patients.