Combination applicator for simultaneous heat and radiation

We present the development of operator and patient friendly conformal applicators that can deliver moderate temperature hyperthermia simultaneously with radiation in superficial tissue overlying contoured anatomy. This applicator combines the uniform heating capabilities of large area conformal microwave array (CMA) flexible printed circuit board applicators with a patient interface (coupling bolus) that facilitates positioning of brachytherapy sources at a fixed distance (e.g. 1.5 cm) from the skin. A customized inverse treatment planning program (IPSA) was used to optimize spacing of a parallel array of source catheters and separation distance from skin, and to characterize the effects of bolus thickness and conformal array curvature on radiation dose uniformity. Performance of a 15 cmx15 cm combination applicator was evaluated in flat and contoured homogenous muscle tissue models. Results demonstrate effective heating and radiation distributions to 1-1.5 cm depth and out to the periphery of the array. This applicator should prove useful for treatment of diffuse chestwall disease located over contoured anatomy that is difficult to treat with external beam radiation. By applying heat and radiation simultaneously for maximum synergism of modalities, this device should expand the number of patients that can benefit from effective thermoradiotherapy for superficial disease.

The use of megavoltage cone-beam CT to complement CT for target definition in pelvic radiotherapy in the presence of hip replacement

In Europe and the USA combined, over half a million people had a hip joint replaced in 2005, contributing to the increasing number of radiotherapy patients with metallic hip prostheses. The treatment plan for external beam radiation therapy is based on the delineation of the anatomy in the planning CT scan. When implanted objects of high atomic number (Z) material are present, however, severe image artefacts are generated in conventional CT, strongly hindering the ability to delineate some organs. This is particularly the case for the planning of prostate patients with hip prostheses. This short communication presents the use of a new imaging modality, megavoltage cone-beam CT, to complement the regular CT for target definition of prostate cancer treatment of patients with hip replacements.

Dose-guided radiation therapy with megavoltage cone-beam CT

Recent advances in fractionated external beam radiation therapy have increased our ability to deliver radiation doses that conform more tightly to the tumour volume. The steeper dose gradients delivered in these treatments make it increasingly important to set precisely the positions of the patient and the internal organs. For this reason, considerable research now focuses on methods using three-dimensional images of the patient on the treatment table to adapt either the patient position or the treatment plan, to account for variable organ locations. In this article, we briefly review the different adaptive methods being explored and discuss a proposed dose-guided radiation therapy strategy that adapts the treatment for future fractions to compensate for dosimetric errors from past fractions. The main component of this strategy is a procedure to reconstruct the dose delivered to the patient based on treatment-time portal images and pre-treatment megavoltage cone-beam computed tomography (MV CBCT) images of the patient. We describe the work to date performed to develop our dose reconstruction procedure, including the implementation of a MV CBCT system for clinical use, experiments performed to calibrate MV CBCT for electron density and to use the calibrated MV CBCT for dose calculations, and the dosimetric calibration of the portal imager. We also present an example of a reconstructed patient dose using a preliminary reconstruction program and discuss the technical challenges that remain to full implementation of dose reconstruction and dose-guided therapy.

Mégavoltage cone-beam CT : récents développements et applications cliniques pour la radiothérapie conformationnelle avec modulation d'intensité

The Megavoltage cone-beam (MV CBCT) system consists of a new a-Si flat panel adapted for MV imaging and an integrated workflow application allowing the automatic acquisition of projection images, cone-beam CT image reconstruction, CT to CBCT image registration and couch position adjustment. This provides a 3D patient anatomy volume in the actual treatment position, relative to the treatment isocenter, moments before the dose delivery, that can be tightly aligned to the planning CT, allowing verification and correction of the patient position, detection of anatomical changes and dose calculation. In this paper, we present the main advantages and performance of this MV CBCT system and summarize the different clinical applications. Examples of the image-guided treatment process from the acquisition of the MV CBCT scan to the correction of the couch position and dose delivery will be presented for spinal and lung lesions and for head and neck, and prostate cancers.

Pegylated liposomal doxorubicin (PLD) with cyclophosphamide (C) as 1st-line chemotherapy for metastatic breast cancer (MBC) patients previously treated with adjuvant anthracyclines

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Background: Anthracyclines (A) are key elements in adjuvant and metastatic chemotherapy regimens for breast cancer. Pre-exposure limits the utilization of A in advanced disease due to cumulative cardiotoxicity. PLD (Caelyx/Doxil) has equivalent activity to conventional doxorubicin in MBC. However PLD has reduced toxicity, including significantly less cardiotoxicity. Combinations of A+C are the backbone of many adjuvant therapies, thus C represents a logical drug to combine with PLD. Methods: MBC patients with measurable disease who completed anthracycline containing adjuvant therapy > 12 months ago were entered in a multi-center single arm phase II trial. They received PLD 35mg/m2 + cyclophosphamide 600 mg/m2 every 3 weeks. This study was powered to demonstrate an objective response rate > 25%. Results: Seventy three patients were enrolled. Prior adjuvant therapy included: AC (37%), CEF/FEC (28%), AC-T (15%), AT (7%), EC (7%). The median cumulative dose of prior A were 240mg/m2 and 580mg/m2 for doxorubicin or epirubicin, respectively. Median time since adjuvant chemotherapy was 4.4 years (1–14). Patients received a median of 6 cycles (2–10) of PLD + C. Major toxicities were; grade 3/4 neutropenia (7.5%), asymptomatic > 10% declines in LVEF (9%) (reversible upon discontinuation of PLD), grade 3/4 hand foot syndrome (6%). Other toxicities were uncommon and usually did not require discontinuation. The objective response rate (ORR) was 38% (4% CR and 34% PR), with an additional 32% having stable disease > 6 months for a clinical benefit of 70% (CB). ORR was similar for patients who had received adjuvant taxanes. Kaplan-Meyer estimated median time to progression was 31.5 weeks (23% progression free). Conclusions: The combination of PLD + C every 3 weeks in patients who have completed adjuvant anthracycline chemotherapy after more than one year prior is well tolerated and has a clinical benefit rate of 70%. This finding is similar to other commonly employed chemotherapeutic regimens for MBC and suggests that re-treatment with a non-cardiotoxic anthracycline following previous anthracycline therapy may be a reasonable therapeutic option for some patients.

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