• An analysis of breast motion using high-frequency, dense surface points captured by an optical sensor during radiotherapy treatment delivery.

      Price, Gareth J; Sharrock, Phillip J; Marchant, Thomas E; Parkhurst, J M; Burton, D; Jain, Pooja; Price, Patricia M; Moore, Christopher J; North Western Medical Physics, The Christie NHS Foundation Trust, Manchester, UK. Gareth.Price@physics.cr.man.ac.uk (2009-11-07)
      Patient motion is an important factor affecting the quality of external beam radiotherapy in breast patients. We analyse the motion of a dense set of surface points on breast patients throughout their treatment schedule to assess the magnitude and stability of motion, in particular, with respect to breast volume. We use an optical sensor to measure the surface motion of 13 breast cancer patients. Patients were divided into two cohorts dependent upon breast volume. Measurements were made during radiotherapy treatment beam delivery for an average of 12 fractions per patient (total 158 datasets). The motion of each surface point is parameterized in terms of its period, amplitude and relative phase. Inter-comparison of the motion parameters across treatment schedules and between patients is made through the creation of corresponding regions on the breast surfaces. The motion period is spatially uniform and is similar in both patient groups (mean 4 s), with the small volume cohort exhibiting greater inter-fraction period variability. The mean motion amplitude is also similar in both groups with a range between 2 mm and 4 mm and an inter-fraction variability generally less than 1 mm. There is a phase lag of up to 0.4 s across the breast, led by the sternum. Breast patient motion is reasonably stable between and during treatment fractions, with the large volume cohort exhibiting greater repeatability than the small volume one.
    • Assessment of bladder motion for clinical radiotherapy practice using cine-magnetic resonance imaging.

      McBain, Catherine A; Khoo, Vincent S; Buckley, David L; Sykes, Jonathan S; Green, Melanie M; Cowan, Richard A; Hutchinson, Charles E; Moore, Christopher J; Price, Patricia M; Academic Department of Radiation Oncology, The University of Manchester, Christie Hospital NHS Foundation Trust, Wilmslow Road, Manchester, United Kingdom. (2009-11-01)
      PURPOSE: Organ motion is recognized as the principal source of inaccuracy in bladder radiotherapy (RT), but there is currently little information on intrafraction bladder motion. METHODS AND MATERIALS: We used cine-magnetic resonance imaging (cine-MRI) to study bladder motion relevant to intrafraction RT delivery. On two occasions, a 28 minute cine-MRI sequence was acquired from 10 bladder cancer patients and 5 control participants immediately after bladder emptying, after abstinence from drinking for the preceding hour. From the resulting cine sequences, bladder motion was subjectively assessed. To quantify bladder motion, the bladder was contoured in imaging volume sets at 0, 14, and 28 min to measure changes to bladder volumes, wall displacements, and center of gravity (COG) over time. RESULTS: The dominant source of bladder motion during imaging was bladder filling (up to 101% volume increase); rectal and small bowel movements were transient, with minimal impact. Bladder volume changes were similar for all participants. However for bladder cancer patients, wall displacements were larger (up to 58 mm), less symmetrical, and more variable compared with nondiseased control bladders. CONCLUSIONS: Significant and individualized intrafraction bladder wall displacements may occur during bladder RT delivery. This important source of inaccuracy should be incorporated into treatment planning and verification.
    • Chemoradiotherapy for locally advanced pancreatic cancer: a radiotherapy dose escalation and organ motion study.

      Henry, Ann M; Ryder, W David J; Moore, Christopher J; Sherlock, David J; Geh, J I; Dunn, P; Price, Patricia M; Academic Department of Radiation Oncology, The University of Manchester, Department of Medical Statistics, Christie Hospital NHS Trust, Manchester, UK. (2008-09)
      AIMS: To determine the efficacy of radiation dose escalation and to examine organ motion during conformal radiotherapy for locally advanced pancreatic cancer. MATERIALS AND METHODS: Thirty-nine patients who were consecutively treated with chemoradiotherapy were studied. Fifteen patients, treated from 1993 to 1997, received 50 Gy in 20 fractions (group I). Twenty-four patients, treated from 1997 to 2003, received an escalated dose of 55 Gy in 25 fractions (group II). Intra-fraction pancreatic tumour motion was assessed in three patients using megavoltage movies during radiation delivery to track implanted radio-opaque markers. RESULTS: Improved survival rates were seen in latterly treated group II patients (P=0.083), who received escalated radiotherapy to smaller treatment volumes due to advances in verification. Worse toxicity effects (World Health Organization grade 3-4) were reported by some patients (<10%), but treatment compliance was similar in both groups, indicating equivalent tolerance. Substantial intra-fraction tumour displacement due to respiratory motion was observed: this was greatest in the superior/inferior (mean=6.6 mm) and anterior/posterior (mean=4.75 mm) directions. Lateral displacements were small (<2 mm). CONCLUSIONS: Dose escalation is feasible in pancreatic cancer, particularly when combined with a reduction in irradiated volume, and enhanced efficacy is indicated. Large, globally applied margins to compensate for pancreatic tumour motion during radiotherapy may be inappropriate. Strategies to reduce respiratory motion, and/or the application of image-guided techniques that incorporate individual patients' respiratory motion into radiotherapy planning and delivery, will probably improve pancreatic radiotherapy.
    • Early clinical evaluation of a novel three-dimensional structure delineation software tool (SCULPTER) for radiotherapy treatment planning.

      McBain, Catherine A; Moore, Christopher J; Green, Matthew M L; Price, Gareth J; Sykes, Jonathan R; Amer, Aminah; Khoo, Vincent S; Price, Patricia M; Academic Department of Radiation Oncology, The University of Manchester, Manchester, UK. (2008-08)
      Modern radiotherapy treatment planning (RTP) necessitates increased delineation of target volumes and organs at risk. Conventional manual delineation is a laborious, time-consuming and subjective process. It is prone to inconsistency and variability, but has the potential to be improved using automated segmentation algorithms. We carried out a pilot clinical evaluation of SCULPTER (Structure Creation Using Limited Point Topology Evidence in Radiotherapy) - a novel prototype software tool designed to improve structure delineation for RTP. Anonymized MR and CT image datasets from patients who underwent radiotherapy for bladder or prostate cancer were studied. An experienced radiation oncologist used manual and SCULPTER-assisted methods to create clinically acceptable organ delineations. SCULPTER was also tested by four other RTP professionals. Resulting contours were compared by qualitative inspection and quantitatively by using the volumes of the structures delineated and the time taken for completion. The SCULPTER tool was easy to apply to both MR and CT images and diverse anatomical sites. SCULPTER delineations closely reproduced manual contours with no significant volume differences detected, but SCULPTER delineations were significantly quicker (p<0.05) in most cases. In conclusion, clinical application of SCULPTER resulted in rapid and simple organ delineations with equivalent accuracy to manual methods, demonstrating proof-of-principle of the SCULPTER system and supporting its potential utility in RTP.
    • Inter-fraction motion and dosimetric consequences during breast intensity-modulated radiotherapy (IMRT).

      Jain, Pooja; Marchant, Thomas E; Green, Melanie M; Watkins, Gillian R; Davies, Julie; McCarthy, Claire; Loncaster, Juliette A; Stewart, Alan L; Magee, Brian; Moore, Christopher J; et al. (2009-01)
      BACKGROUND AND PURPOSE: Intensity-modulated radiotherapy (IMRT) can improve dose homogeneity within the breast planned target volume (PTV), but may be more susceptible to patient/organ motion than standard tangential radiotherapy (RT). We used daily cone-beam CT (CBCT) imaging to assess inter-fraction motion during breast IMRT and its subsequent impact on IMRT and standard RT dose homogeneity. MATERIALS AND METHODS: Ten breast cancer patients selected for IMRT were studied. CBCT images were acquired immediately after daily treatment. Automatic image co-registration was used to determine patient positioning variations. Daily PTV contours were used to calculate PTV variations and daily delivered IMRT and theoretically planned tangential RT dose. RESULTS: Group systematic (and random) setup errors detected by CBCT were 5.7 (3.9)mm laterally, 2.8 (3.5)mm vertically and 2.3 (3.2)mm longitudinally. Rotations >2 degrees in any axis occurred on 53/106 (50%) occasions. Daily PTV volume varied up to 23%. IMRT dose homogeneity was superior at planning and throughout the treatment compared with standard RT (1.8% vs. 15.8% PTV received >105% planned mean dose), despite increased motion sensitivity. CONCLUSIONS: CBCT revealed inadequacies of current patient positioning and verification procedures during breast RT and confirmed improved dose homogeneity using IMRT for the patients studied.
    • Monitoring dosimetric impact of weight loss with kilovoltage (kV) cone beam CT (CBCT) during parotid-sparing IMRT and concurrent chemotherapy.

      Ho, Kean F; Marchant, Thomas E; Moore, Christopher J; Webster, Gareth J; Rowbottom, Carl G; Pennington, Hazel; Lee, Lip W; Yap, Beng K; Sykes, Andrew J; Slevin, Nicholas J; et al. (2012-03-01)
      Parotid-sparing head-and-neck intensity-modulated radiotherapy (IMRT) can reduce long-term xerostomia. However, patients frequently experience weight loss and tumor shrinkage during treatment. We evaluate the use of kilovoltage (kV) cone beam computed tomography (CBCT) for dose monitoring and examine if the dosimetric impact of such changes on the parotid and critical neural structures warrants replanning during treatment.
    • 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.