Applications of Accelerators and Detectors to Cancer Treatment

Abstract:

Background

To establish a common database on particle therapy for the evaluation of clinical studies integrating a large variety of voluminous datasets, different documentation styles, and various information systems, especially in the field of radiation oncology.

Methods

We developed a web-based documentation system for transnational and multicenter clinical studies in particle therapy. 560 patients have been treated from November 2009 to September 2011. Protons, carbon ions or a combination of both, as well as a combination with photons were applied. To date, 12 studies have been initiated and more are in preparation.

Results

It is possible to immediately access all patient information and exchange, store, process, and visualize text data, any DICOM images and multimedia data. Accessing the system and submitting clinical data is possible for internal and external users. Integrated into the hospital environment, data is imported both manually and automatically. Security and privacy protection as well as data validation and verification are ensured. Studies can be designed to fit individual needs.

Conclusions

The described database provides a basis for documentation of large patient groups with specific and specialized questions to be answered. Having recently begun electronic documentation, it has become apparent that the benefits lie in the user-friendly and timely workflow for documentation. The ultimate goal is a simplification of research work, better study analyses quality and eventually, the improvement of treatment concepts by evaluating the effectiveness of particle therapy.

Abstract:

Background

Treatment standard for patients with rectal cancer depends on the initial staging and includes surgical resection, radiotherapy as well as chemotherapy. For stage II and III tumors, radiochemotherapy should be performed in addition to surgery, preferentially as preoperative radiochemotherapy or as short-course hypofractionated radiation. Advances in surgical approaches, especially the establishment of the total mesorectal excision (TME) in combination with sophisticated radiation and chemotherapy have reduced local recurrence rates to only few percent. However, due to the high incidence of rectal cancer, still a high absolute number of patients present with recurrent rectal carcinomas, and effective treatment is therefore needed.Carbon ions offer physical and biological advantages. Due to their inverted dose profile and the high local dose deposition within the Bragg peak precise dose application and sparing of normal tissue is possible. Moreover, in comparison to photons, carbon ions offer an increase relative biological effectiveness (RBE), which can be calculated between 2 and 5 depending on the cell line as well as the endpoint analyzed.Japanese data on the treatment of patients with recurrent rectal cancer previously not treated with radiation therapy have shown local control rates of carbon ion treatment superior to those of surgery. Therefore, this treatment concept should also be evaluated for recurrences after radiotherapy, when dose application using conventional photons is limited. Moreover, these patients are likely to benefit from the enhanced biological efficacy of carbon ions.

Methods and design

In the current Phase I/II-PANDORA-01-Study the recommended dose of carbon ion radiotherapy for recurrent rectal cancer will be determined in the Phase I part, and feasibilty and progression-free survival will be assessed in the Phase II part of the study.Within the Phase I part, increasing doses from 12 × 3 Gy E to 18 × 3 Gy E will be applied.The primary endpoint in the Phase I part is toxicity, the primary endpoint in the Phase II part is progression-free survival.

Discussion

With conventional photon irradiation treatment of recurrent rectal cancer is limited, and the clinical effect is only moderate. With carbon ions, an improved outcome can be expected due to the physical and biological characteristics of the carbon ion beam. However, the optimal dose applicable in this clincial situation as re-irradiation still has to be determined. This, as well as efficacy, is to be evaluated in the present Phase I/II trial.

Trial registration

NCT01528683.

Abstract:

Purpose

Microdosimetric quantities can be used to estimate the biological effectiveness of radiation fields. This study evaluates the capability of the general-purpose Monte Carlo code FLUKA to simulate microscopic patterns of energy depositions for mixed radiation fields which are created by carbon ions at therapeutic energies in phantoms.

Materials and methods

Measured lineal energy spectra and linear energy transfer (LET) spectra produced by carbon ions of about 300 MeV/n at different depths in phantoms representing human tissue were chosen from published literature and were compared with results from simulations of the measurement set-ups with FLUKA.

Results

Simulations of the dose-weighted lineal energy spectra yd(y) and dose-weighted LET spectra describe the main features of the respective measured spectra. All simulated frequency mean and dose mean lineal energy values are, respectively, within 21% and 11% of the measured ones. A slight underestimation of fragment fluences is notable. It is shown that the simultaneous detection of several charged fragments in the TEPC ('V effect') has considerable impact on the measured lineal energy spectra of fragments.

Conclusions

Agreement between measurements and FLUKA results is encouraging and shows that FLUKA can predict microdosimetric spectra of mixed radiation fields created by therapeutic carbon ions in phantoms reasonably well.

Abstract:

For both cancer therapy with protons and ions (hadron therapy) and space radiation environments, the spatial energy deposition patterns of the radiation fields are of importance for quantifying the resulting radiation damage in biological structures. Tissue-equivalent proportional counters (TEPC) are the principal instruments for measuring imparted energy on a microscopic scale and for characterizing energy deposition patterns of radiation. Moreover, the distribution of imparted energy can serve as a complementary quantity to particle fluences of the primary beam and secondary fragments for characterizing a radiation field on a physical basis for radiobiological models. In this work, the Monte Carlo particle transport code FLUKA is used for simulating energy depositions in TEPC by ion beams. The capability of FLUKA in predicting imparted energy and derived quantities, such as lineal energy, for microscopic volumes is evaluated by comparing it with a large set of TEPC measurements for different ion beams with atomic numbers ranging from 1 to 26 and energies from 80 up to 1000 MeV/n. The influence of different physics configurations in the simulation is also discussed. It is demonstrated that FLUKA can simulate energy deposition patterns of ions in TEPC cavities accurately and that it provides an adequate description of the main features of the spectra.