Field-in-field technique for upper abdominal malignancies in clinical radiotherapy.
BACKGROUND
In upper abdominal malignancies (UAM), due to the presence of multiple inhomogeneous tissues, a wedge-based conformal treatment planning results in high-dose regions inside the target volume.


OBJECTIVE
This study was designed to explore the feasibility of using a field-in-field (FIF) technique in different UAM and its efficacy in reducing the high-dose regions.


METHODS
Twelve patients of UAM (which included malignancies of the gastroesophageal junction, stomach, gall bladder, and pancreas) were selected for this study. Computed tomography (CT) scans were performed and three-dimensional conformal wedge plans were generated for all the cases. The same plan was copied with the wedges removed and a FIF plan was generated. The two plans were compared for mean, maximum, and median doses; dose received by 2% (D2) and 98% (D98) of the target volume; volume receiving> 107% (V > 107%) and < 95% (V Statistical Analysis: Statistical analysis was performed with SPSS, version 10.0.


RESULTS
For all the cases, the FIF technique was better than wedge-based planning in terms of maximum dose, D2, V > 107%, and CI; there was a statistically significant reduction in monitor units. With regard to doses to critical structures, there was marginal dose reduction for the kidneys and spinal cord with FIF as compared to wedge-based planning.


CONCLUSIONS
The FIF technique can be employed for UAM in place of wedge-based conformal treatment plans.
Prabhakar
R
R
Department of Radiation Oncology, Institute Rotary Cancer Hospital, All India Institute of Medical Sciences, New Delhi - 110 029, India. prabhakar_smr@hotmail.com
Haresh
K P
KP
Kumar
M
M
Sharma
D N
DN
Julka
P K
PK
Rath
G K
GK
D000008:Abdominal Neoplasms / Q000532:radiotherapy*; D004307:Dose-Response Relationship, Radiation; D006801:Humans; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000295:instrumentation / Q000379:methods*; D020266:Radiotherapy, Conformal; D014057:Tomography, X-Ray Computed