Brachytherapy
Volume 5, Issue 4 , Pages 223-229, October 2006

Comparative assessment of doses to tumor, rectum, and bladder as evaluated by orthogonal radiographs vs. computer enhanced computed tomography-based intracavitary brachytherapy in cervical cancer

  • Niloy Ranjan Datta

      Affiliations

    • Department of Radiotherapy, Regional Cancer Centre, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow, India
    • Corresponding Author InformationCorresponding author. Department of Radiotherapy, Regional Cancer Centre, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Rae Barelli Road, Lucknow - 226014, India. Tel.:/fax: +91-522-2668476.
    • ,
  • Anurita Srivastava

      Affiliations

    • Department of Radiotherapy, Regional Cancer Centre, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow, India
    • ,
  • Koilpillai Joseph Maria Das

      Affiliations

    • Department of Radiotherapy, Regional Cancer Centre, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow, India
    • ,
  • Archana Gupta

      Affiliations

    • Department of Radiodiagnosis & Imaging, Regional Cancer Centre, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow, India
    • ,
  • Neeraj Rastogi

      Affiliations

    • Department of Radiotherapy, Regional Cancer Centre, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow, India

Received 19 April 2006; received in revised form 28 August 2006; accepted 6 September 2006.

Abstract 

Purpose

To carry out a comparative assessment of intracavitary brachytherapy (ICBT) doses to tumor, bladder, and rectum based on orthogonal films and contrast enhanced computed tomography (CECT).

Methods and materials

Fifty-five ICBT procedures with CT/MRI compatible applicator and CECT scans were evaluated. Doses to Point A, International Commission on Radiation Units and Measurement (ICRU) reference points for maximum bladder (Bmax(ICRU)) and rectum (Rmax(ICRU)) localized from orthogonal films were compared with CECT delineated tumor, bladder (Bmax(CECT)), and rectum (Rmax(CECT)) doses, respectively. The 95th and 90th percentile bladder (B95(CECT) and B90(CECT)) and rectal (R95(CECT) and R90(CECT)) doses based on CECT were also estimated.

Results

Mean percentage tumor volume encompassed within the prescribed dose of 600cGy to Point A was 88.8%. Mean Bmax(ICRU), Bmax(CECT), Rmax(ICRU), and Rmax(CECT) were 631.3cGy, 1221.4cGy, 454.8cGy, and 526.9cGy, respectively. Paired mean differences were significant between Bmax(ICRU) and Bmax(CECT) or B95(CECT) (both p<0.001); Rmax(ICRU) and Rmax(CECT) (p=0.005) or R90(CECT) (p<0.001), whereas insignificant for Bmax(ICRU) and B90(CECT) (p=0.281), and Rmax(ICRU) and R95(CECT) (p=0.372).

Conclusions

Prescription based on Point A ICBT doses could lead to uncertainty and underdosage in tumor. ICRU 38 maximum bladder and rectal doses significantly underestimate the maximum doses to these organs and represent the 90th and 95th percentile of the maximum doses to these organs, respectively.

Keywords: Cervix cancer, Intracavitary brachytherapy, Radiation dosimetry, Image-based brachytherapy

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PII: S1538-4721(06)00250-9

doi:10.1016/j.brachy.2006.09.001

Brachytherapy
Volume 5, Issue 4 , Pages 223-229, October 2006

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