Dosimetric comparison of helical tomotherapy treatment and step-and-shoot intensity-modulated radiotherapy of retroperitoneal sarcoma.
OBJECTIVE
To compare step-and-shoot intensity-modulated radiation therapy (SAS-IMRT) and helical tomotherapy (Tomo) dosimetry plans for patients who have received adjuvant radiation therapy for retroperitoneal sarcomas (RSTS).


METHODS
A retrospective review was performed for seven patients who received either SAS-IMRT or Tomo as adjuvant radiation therapy for RSTS. In each case, a treatment plan of the other modality was generated so that SAS-IMRT and Tomo could be compared.


RESULTS
The average percentage of clinical target volume (CTV) that received less than the prescription dose was 1.4% for Tomo compared to 3.8% for SAS-IMRT. Both SAS-IMRT and Tomo plans provided comparable and significant reductions in volume of small bowel receiving greater than 45 Gy compared to simple opposing standard radiation fields. For the ipsilateral kidney, Tomo significantly reduced the volume of kidney that received at least 15 Gy (average 22% for Tomo vs. 56% for SAS-IMRT).


CONCLUSIONS
Both SAS-IMRT and Tomo can encompass the large CTV often required for patients with RSTS, although Tomo provides superior dose uniformity. Both SAS-IMRT and Tomo can minimize the volume of small bowel receiving greater than 45 Gy. Tomo was superior to SAS-IMRT in minimizing the volume of ipsilateral kidney irradiated to greater than 15 Gy when the CTV is adjacent to a kidney. Dose escalation and target margin expansion may thus become realistic possibilities.
Pezner
Richard D
RD
Division of Radiation Oncology, City of Hope Medical Center, Duarte, CA 91010, USA. RPezner@coh.org
Liu
An
A
Han
Chunhui
C
Chen
Yi-Jen
YJ
Schultheiss
Timothy E
TE
Wong
Jeffrey Y C
JY
D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D007421:Intestine, Small / Q000000981:diagnostic imaging / Q000528:radiation effects; D007668:Kidney / Q000000981:diagnostic imaging / Q000528:radiation effects; D008297:Male; D008875:Middle Aged; D011879:Radiotherapy Dosage; D018714:Radiotherapy, Adjuvant; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods*; D012186:Retroperitoneal Neoplasms / Q000532:radiotherapy*; D012189:Retrospective Studies; D012509:Sarcoma / Q000532:radiotherapy*; D036542:Tomography, Spiral Computed / Q000379:methods*