Publications by authors named "Catherine Philippson"

5 Publications

  • Page 1 of 1

Unintended dose to the lower axilla in adjuvant radiotherapy for breast cancer: Differences between tangential beam and VMAT.

Radiother Oncol 2021 11 11;164:282-288. Epub 2021 Oct 11.

Department of Radiation Oncology, Breast Working Group, Institut Jules Bordet, Université libre de Bruxelles, Brussels, Belgium. Electronic address:

Background And Purpose: To evaluate dosimetric differences in unintended dose to the lower axilla between 3D-standard (3DCRT), tangential beam forward intensity modulated radiotherapy (F-IMRT) and volumetric modulated arc therapy (VMAT). The objective is to evaluate whether results of clinical trials, such as the ACOSOG-Z011 trial, that evaluated omission of axillary clearance can be extrapolated towards more conformal techniques like VMAT.

Materials And Methods: Twenty-five consecutive patients treated with whole breast radiotherapy alone (WBRT) using a F-IMRT technique were identified. Three additional plans were created for every patient: one plan using a single 270° arc (VMAT 1x270°), another using two small ≤90° opposing arcs (VMAT 2x < 90°) and thirdly a 3DCRT plan without F-IMRT. Axillary levels I-II were contoured after the treatment plans were made.

Results: The volume of the axilla level I that was covered by the 50% isodose (V50%) was significantly higher for VMAT 2x < 90° (71.3 cm, 84% of structure volume, p < 0.001) and VMAT 1x270° (68.8 cm, 81%, p < 0.01) compared to 3DCRT (60.3 cm, 71%) and F-IMRT (60.8 cm, 72%). The V50% to the axilla level II, however, was low for all techniques: 12.3 cm (12%); 8.9 cm (9%); 4.3 cm (4%); 4.4 cm (4%) for VMAT 2x < 90°, VMAT 1x270°, 3DCRT, F-IMRT, respectively. For the higher doses (V90% and above), no clinically relevant differences were seen between the different modalities.

Conclusion: WBRT treatments with VMAT do not lead to a significant reduction of the unintended axillary dose in comparison with a tangential beam setup. Hence, concerning tumor control, VMAT can be applied to clinical situations similar to the Z0011 trial. The intermediate axillary dose is higher with VMAT, but the clinical consequence of this difference on toxicity is unknown.
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November 2021

3D Monte Carlo dosimetry of intraoperative electron radiation therapy (IOERT).

Phys Med 2019 Jan 15;57:207-214. Epub 2019 Jan 15.

Nuclear Metrology, Ecole Polytechnique, Université Libre de Bruxelles, Bruxelles, Belgium; Radiothérapy Department, Institut Jules Bordet, Bruxelles, Belgium.

Purpose: This paper studies the feasibility of using Monte Carlo (MC) for treatment planning of intraoperative electron radiation therapy (IOERT) procedure to get 3D dose by using patient's CT images.

Methods: The IOERT treatment planning was performed using the following successive steps: I) The Mobetron 1000® machine was modelled with the EGSnrc MC codes. II) The MC model was validated with measurements of percentage depth doses and profiles for three energies (12, 9, 6) MeV. III) CT images were imported as DICOM files. IV) Contouring of the planning target volume (PTV) and the organs at risk was done by the radiation oncologist. V) The medical physicist with the radiation oncologist, had chosen the same parameters of IOERT procedures like energy, applicator (type, size) and using or not bolus. VI) Finally, dose calculation and analysis of 3D maps was carried out.

Results: The tuning process of the MC model provides good results, as the maximum value of the root mean square deviation (RMSD) was less than 3% between the MC simulated PDDs and the measured PDDs. The contouring and dose analysis review were easy to conduct for the classical treatment planning system. The radiation oncologist had many tools for dose analysis such as DVH and color wash for all the slides. Summation of the 3D dose of IOERT with other radiotherapy plans is possible and helpful for total dose estimation. Archiving and documentation is as good as treatment planning system (TPS).

Conclusions: The method displayed in this paper provides a step forward for IOERT Dosimetry and allows to obtain accurate dosimetry of treated volumes.
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January 2019

Shielding disk position in intra-operative electron radiotherapy (IOERT): A Monte Carlo study.

Phys Med 2018 Jul 15;51:1-6. Epub 2018 Jun 15.

Radiotherapy Department, Institute Jules Bordet, Belgium. Electronic address:

Purpose: In IOERT breast treatments, a shielding disk is frequently used to protect the underlying healthy structures. The disk is usually composed of two materials, a low-Z material intended to be oriented towards the beam and a high-Z material. As tissues are repositioned around the shield before treatment, the disk is no longer visible and its correct alignment with respect to the beam is guaranteed. This paper studies the dosimetric characteristics of four possible clinical positioning scenarios of the shielding disk. A new alignment method for the shielding disk in the beam is introduced. Finally, it suggests a new design for the shielding disk.

Methods: As the first step, the IOERT machine "Mobetron 1000" was modeled by using Monte Carlo simulation, tuning the MC model until an excellent match with the measured PDDs and profiles was achieved. Four possible shielding disk positioning scenarios were considered, determining the dosimetric impact. Furthermore, in our center, to prevent beam misalignment, we have developed a shielding disk equipped with guiding rods. Having ascertained a correct alignment between the disk and the beam, we can propose a new internal design of the shielding disk that can improve the dose distribution with a better coverage of the treated area.

Results: All MC simulations were performed with a 12 MeV beam, the maximum energy of Mobetron 1000 and a 5.5 cm diameter flat tip applicator, this applicator being the most clinically used. The simulations were compared with measurements performed in a water phantom and showed good results within 2.2% of root mean square difference (RMSD). The misplacement positions of the shielding disk have dosimetric impacts in the treatment volume and a small translation could have a significant influence on healthy tissues. The D-scenario is the worst which could happens when the shielding disk is flipped upside down, giving up to 144% dose instead of 90% at the surface of the Pb/Al shielding disk. A new shielding design used, together with our alignment tool, is able to give a more homogeneous dose in the target area.

Conclusions: The accuracy of shielding disk position can still be problematic in IOERT dosimetry. Any method that can ascertain the good alignment between the shielding disk and the beam is beneficial for the dose distribution and is a prerequisite for an optimized shield internal design that could improve the coverage of the treated area and the protection of healthy tissues.
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July 2018

Special focus on cardiac toxicity of different sequences of adjuvant doxorubicin/docetaxel/CMF regimens combined with radiotherapy in breast cancer patients.

Radiother Oncol 2009 Jan 14;90(1):116-21. Epub 2008 Nov 14.

Radiotherapy Department, Institut Jules Bordet, Bruxelles, Belgium.

Background And Purpose: Cardiac toxicity associated with anthracyclines and taxanes and/or radiotherapy (RT) can be life-threatening and can adversely affect quality of life. The aim was to evaluate treatment-related cardiac toxicity in breast cancer patients treated with doxorubicin/docetaxel/CMF sequential or combined regimens and RT.

Methods And Materials: From 1996 to 1998, 64 patients with stages II-III breast cancer were included in a pilot study that investigated the efficacy/feasibility of sequential and combined doxorubicin/docetaxel/CMF regimens. No patients had any cardiovascular history or ECG abnormalities. The same RT technique was performed in all patients. LVEF measurements were obtained at baseline, during, at the end of chemotherapy, at the end of radiotherapy and subsequently during the follow-up. A cardiac event was defined as a myocardial infraction or clinical evidence of congestive heart failure.

Results: Median age was 48 years (range 29-65 years). The median follow-up was 6 years. Significant drop in the post-treatment LVEF occurred in 21 patients (median decrease of 10%). Notwithstanding, all patients have preserved normal cardiac function and regained their initial LVEF value during follow-up. No cardiac events were reported.

Conclusion: Sequential and combined doxorubicin/docetaxel/CMF regimens plus conventional RT in selected non high-risk cardiac patients are relatively safe without cardiac toxicity at mid-term follow-up.
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January 2009

HSP110, caspase-3 and -9 expression in physiological apoptosis and apoptosis induced by in vivo embryonic exposition to all-trans retinoic acid or irradiation during early mouse eye development.

J Anat 2007 May;210(5):532-41

Department of Anatomy and Embryology, Université Libre de Bruxelles, Faculty of Medicine, Brussels, Belgium.

Apoptosis is an essential physiological process in embryonic development. In the developing eye of vertebrates, three periods of developmental apoptosis can be distinguished: early, intermediate and later. Within the apoptosis pathway, caspases play a crucial role. It has also been shown that HSP110 may have a potential role in apoptosis. The aim of this research was to study the expression of HSP110, caspase-3 and -9 in physiological, retinoic- or irradiation-induced apoptosis during early eye development. Seven pregnant C57Bl/6J mice received 80 mg kg(-1) of all-trans retinoic acid mixed with sesame oil. Seven pregnant NMRI mice received 2 Gy irradiation at the same gestational day. Control mice of both strains (seven mice of each) were not submitted to any treatment. Embryos were harvested at 3, 6, 12 and 24 h after exposition, fixed, dehydrated and embedded. Coronal sections (5 microm) were made. Slide staining occurred alternatively using anti-caspase-3, anti-caspase-9 and anti-HSP110 immunohistochemistry. HSP110 and caspase-3 expression presented similar topographic and chronological patterns, whereas expression of HSP110 was more precocious in retinoic acid-treated embryos. After retinoic exposure, caspase-3- and HSP110-positive cells were increased in the region of the optic vesicle. By contrast, after irradiation, caspase-3- and HSP110-positive cells were noticeably increased in the optic vesicle, peri-optical mesoderm but less in lens placode. HSP110 was expressed before caspase-3. By contrast, caspase-9 was expressed by a very small number of cells in the optic vesicle either under physiological or under teratogenic conditions. Thus, it seems that activation of caspase-9 is dispensable in early eye developmental apoptosis.
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May 2007