• Dynamic contrast-enhanced MRI for prostate cancer localization.

      Jackson, Andrew; Reinsberg, S A; Sohaib, S A; Charles-Edwards, E M; Jhavar, S; Christmas, T J; Thompson, A C; Bailey, M J; Corbishley, C M; Fisher, C; et al. (2009-02)
      Radiotherapy dose escalation improves tumour control in prostate cancer but with increased toxicity. Boosting focal tumour only may allow dose escalation with acceptable toxicity. Intensity-modulated radiotherapy can deliver this, but visualization of the tumour remains limiting. CT or conventional MRI techniques are poor at localizing tumour, but dynamic contrast-enhanced MRI (DCE-MRI) may be superior. 18 patients with prostate cancer had T(2) weighted (T2W) and DCE-MRI prior to prostatectomy. The prostate was sectioned meticulously so as to achieve accurate correlation between imaging and pathology. The accuracy of DCE-MRI for cancer detection was calculated by a pixel-by-pixel correlation of quantitative DCE-MRI parameter maps and pathology. In addition, a radiologist interpreted the DCE-MRI and T2W images. The location of tumour on imaging was compared with histology, and the accuracy of DCE-MRI and T2W images was then compared. Pixel-by-pixel comparison of quantitative parameter maps showed a significant difference between the benign peripheral zone and tumour for the parameters K(trans), v(e) and k(ep). Calculation of areas under the receiver operating characteristic curve showed that the pharmacokinetic parameters were only "fair" discriminators between cancer and benign gland. Interpretation of DCE-MRI and T2W images by a radiologist showed DCE-MRI to be more sensitive than T2W images for tumour localization (50% vs 21%; p = 0.006) and similarly specific (85% vs 81%; p = 0.593). The superior sensitivity of DCE-MRI compared with T2W images, together with its high specificity, is arguably sufficient for its use in guiding radiotherapy boosts in prostate cancer.
    • Radical chemoradiotherapy for adenocarcinoma of the distal oesophagus and oesophagogastric junction: what planning margins should we use?

      Whitfield, Gillian A; Jackson, Andrew; Moore, Christopher J; Price, Patricia M; Academic Department of Radiation Oncology, University of Manchester, Manchester, UK. gillian.whitfield@manchester.ac.uk (2008-12)
      Distal oesophageal and Type I-II oesophagogastric junctional adenocarcinomas have a poor prognosis. In radical chemoradiotherapy, consensus is lacking on radiotherapy margins. Here, we review the effect of common imaging modalities on the extent of the gross tumour volume (GTV) and the evidence for margins. To do this, papers were identified from PubMed, and geometric uncertainties were combined using the British Institute of Radiology formula. CT and endoscopic ultrasound were best for GTV delineation, but the role of positron emission tomography is uncertain. Evidence suggests 3 cm proximal and 5 cm distal GTV-CTV (clinical target volume) margins (along the mucosa) for advanced tumours, but is lacking for early tumours and radial margins. Nodal spread, present in most pT2 tumours, is strongly prognostic and is initially to regional nodes (not wholly covered by typical radiotherapy). Calculated CTV-PTV (planning target volume) margins for three-dimensional conformal radiotherapy using literature estimates of tumour motion and set-up errors with bony online set-up correction, ignoring delineation errors, are 2.2 cm superiorly (sup) and inferiorly (inf) and 1.2-1.3 cm radially (1.3 cm sup-inf; 0.8 cm radially if the tumour's mid-position is known). As these margins may risk excessive toxicity, we propose treating microscopic disease for potentially curable tumours (cT2N0, some cT3N0), but gross disease only for advanced tumours. Recommended GTV-CTV margins are a maximum of 3 cm proximally and 5 cm distally up to cT2N0; 3 cm proximally and 5 cm distally for cT3N0 if anticipated toxicity allows; and 0 cm for cT4 and most node-positive tumours. The CTV-PTV margins above must be added to this for all stages. Methods of including elective nodal areas close to the GTV should be researched, e.g. nodal maps and intensity-modulated radiotherapy.
    • Rectal motion can reduce CTV coverage and increase rectal dose during prostate radiotherapy: A daily cone-beam CT study.

      Sripadam, Raj; Stratford, Julia; Henry, Ann M; Jackson, Andrew; Moore, Christopher J; Price, Patricia M; Clatterbridge Centre for Oncology, Bebington, Wirral, UK. (2009-03)
      BACKGROUND AND PURPOSE: Daily on-treatment verification cone-beam CT (CBCT) was used to study the effect of rectal motion on clinical target volume (CTV) coverage during prostate radiotherapy. MATERIAL AND METHODS: CBCT scans were acquired from 15 patients immediately after daily treatment. From these images, the rectum was contoured allowing the analysis of rectal volume cross-sectional area (CSA) and the determination of rectal dose. Rectal wall motion was quantified as a surrogate measure of prostate displacement and CTV coverage was subjectively assessed. RESULTS: Rectal volume decreased over the treatment course in 13 patients (P<0.001). Rectal wall regions corresponding to the prostate base displayed the greatest motion; larger displacements were seen in patients with larger rectal planning volumes. CTV coverage was inadequate, at the prostate base only, in 38% of the fractions delivered to 4/7 patients with a large rectum at planning (>100 cm(3)). In patients with small rectum at planning (<50 cm(3)) up to 25% more rectal volume than predicted was included in the high-dose region. CONCLUSIONS: Rectal motion during treatment in prostate cancer patients has implications for CTV coverage and rectal dose. Measures to ensure consistency in daily rectal volume or image-guided strategies should be considered.