UCL  IRIS
Institutional Research Information Service
UCL Logo
Please report any queries concerning the funding data grouped in the sections named "Externally Awarded" or "Internally Disbursed" (shown on the profile page) to your Research Finance Administrator. Your can find your Research Finance Administrator at https://www.ucl.ac.uk/finance/research/rs-contacts.php by entering your department
Please report any queries concerning the student data shown on the profile page to:

Email: portico-services@ucl.ac.uk

Help Desk: http://www.ucl.ac.uk/ras/portico/helpdesk
Publication Detail
Assessment of the impact of CT calibration procedures for proton therapy planning on paediatric treatments.
  • Publication Type:
    Journal article
  • Publication Sub Type:
    Article
  • Authors:
    Bär E, Collins-Fekete C-A, Rompokos V, Zhang Y, Gaze MN, Warry A, Poynter A, Royle G
  • Publisher:
    American Association of Physicists in Medicine
  • Publication date:
    26/06/2021
  • Journal:
    Medical Physics
  • Status:
    Published
  • Country:
    United States
  • Print ISSN:
    0094-2405
  • Language:
    eng
  • Keywords:
    dual-energy CT, imaging for protons, paediatric cancer, paediatric treatment planning
Abstract
PURPOSE: Relative stopping powers (RSP) for proton therapy are estimated using single-energy CT (SECT), calibrated with standardised tissues of the adult male. It is assumed that those tissues are representative of tissues of all age and sex. Female, male and paediatric tissues differ from one another in density and composition. In this study, we use tabulated paediatric tissues and computational phantoms to investigate the impact of this assumption on paediatric proton therapy. The potential of dual-energy CT (DECT) to improve the accuracy of these calculations is explored. METHODS: We study 51 human body tissues, categorised into male/female for the age groups newborn, 1-, 5-, 10-, 15-year old and adult, with given compositions and densities. CT numbers are simulated and RSPs are estimated using SECT and DECT methods. Estimated tissue RSPs from each method are compared to theoretical RSP. The dose and range errors of each approach is evaluated on 3 computational phantoms (Ewing's sarcoma, salivary sarcoma, glioma) derived from paediatric proton therapy patients. RESULTS: With SECT, soft tissues have mean estimation errors and standard deviation up to (1.96 ± 4.18)% observed in newborns, compared to (0.20 ± 1.15)% in adult males. Mean estimation errors for bones are up to (-3.35 ± 4.76)% in paediatrics as opposed to (0.10 ± 0.66)% in adult males. With DECT, mean errors reduce to (0.17 ± 0.13)% and (0.23 ± 0.22)% in newborns (soft tissues/bones). With SECT, dose errors in a Ewing's sarcoma phantom are exceeding 5 Gy (10% of prescribed dose) at the distal end of the treatment field, with volumes of dose errors >5 Gy of Vdiff> 5 = 4630.7mm3 . Similar observations are made in the head and neck phantoms, with overdoses to healthy tissue exceeding 2 Gy (4%). A systematic Bragg peak shift resulting in either over- or underdosage of healthy tissues and target volumes depending on the crossed tissues RSP prediction errors is observed. Water equivalent range errors of single beams are between -1.53mm and 5.50mm (min, max) (Ewing's sarcoma phantom), -0.78mm and 3.62mm (salivary sarcoma phantom), and -0.43mm and 1.41mm (glioma phantom). DECT can reduce dose errors to <1 Gy and range errors to <1 mm. CONCLUSION: SECT estimates RSPs for paediatric tissues with systematic shifts. DECT improves the accuracy of RSPs and dose distributions in paediatric tissues compared to the SECT calibration curve based on adult males tissues.
Publication data is maintained in RPS. Visit https://rps.ucl.ac.uk
 More search options
UCL Researchers
Author
Dept of Med Phys & Biomedical Eng
Author
Dept of Med Phys & Biomedical Eng
University College London - Gower Street - London - WC1E 6BT Tel:+44 (0)20 7679 2000

© UCL 1999–2011

Search by