• 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.
    • 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.
    • 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.
    • 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.