TY - JOUR
T1 - Role of in vivo dosimetry with radiochromic films for dose verification during cutaneous radiation therapy
AU - Liu, Hong Wei
AU - Gräfe, James
AU - Khan, Rao
AU - Olivotto, Ivo
AU - Barajas, J. Eduardo Villarreal
N1 - Publisher Copyright:
© 2015 Liu et al.; licensee BioMed Central.
PY - 2015/1/10
Y1 - 2015/1/10
N2 - Purpose: To evaluate the role of in vivo dosimetry with radiochromic films for dose verification in cutaneous radiation therapy (RT). Methods: Five patients with 8 cutaneous or sub-cutaneous malignancies of the face, neck, trunk and extremity receiving RT were included. Orthovoltage, megavoltage photon therapies were applied based on anatomic location. The delivered dose for each target was measured with GAFCHROMIC EBT3TM film. The differences between the prescribed and measured doses in each target were analyzed based on the RT characteristics, target location and custom patient set up. The accuracy of EBT3TM film measurement was verified by measurements in a solid water phantom. Results: The mean measured dose was -3.2% (-9.6% to +2.3%, P=0.86) lower than prescribed over 23 measurements. A wide range of under dose was detected in orthovoltage therapy when a gap existed between skin and a closed-ended applicator surface. The magnitude of the under dosage was correlated with the degree of the gap (P=0.01). The phantom study confirmed the accuracy of GAFCHROMIC EBT3TM film measurement and found that the low measured dose in orthovoltage therapy was caused by the deviation from the inverse square law (ISL) of the beam output at extended source surface distance (SSD) for closed-ended applicators. Conclusions: A significantly low delivered dose for extended SSD orthovoltage therapy was demonstrated during cutaneous RT. The dose fall-off with distance is not completely compensated by the ISL standoff correction for orthovoltage therapy. GAFCHROMIC EBT3™ film is a useful and accurate tool for quality assurance of patients receiving a curative intended cutaneous RT.
AB - Purpose: To evaluate the role of in vivo dosimetry with radiochromic films for dose verification in cutaneous radiation therapy (RT). Methods: Five patients with 8 cutaneous or sub-cutaneous malignancies of the face, neck, trunk and extremity receiving RT were included. Orthovoltage, megavoltage photon therapies were applied based on anatomic location. The delivered dose for each target was measured with GAFCHROMIC EBT3TM film. The differences between the prescribed and measured doses in each target were analyzed based on the RT characteristics, target location and custom patient set up. The accuracy of EBT3TM film measurement was verified by measurements in a solid water phantom. Results: The mean measured dose was -3.2% (-9.6% to +2.3%, P=0.86) lower than prescribed over 23 measurements. A wide range of under dose was detected in orthovoltage therapy when a gap existed between skin and a closed-ended applicator surface. The magnitude of the under dosage was correlated with the degree of the gap (P=0.01). The phantom study confirmed the accuracy of GAFCHROMIC EBT3TM film measurement and found that the low measured dose in orthovoltage therapy was caused by the deviation from the inverse square law (ISL) of the beam output at extended source surface distance (SSD) for closed-ended applicators. Conclusions: A significantly low delivered dose for extended SSD orthovoltage therapy was demonstrated during cutaneous RT. The dose fall-off with distance is not completely compensated by the ISL standoff correction for orthovoltage therapy. GAFCHROMIC EBT3™ film is a useful and accurate tool for quality assurance of patients receiving a curative intended cutaneous RT.
KW - Extended source surface distance
KW - GAFCHROMIC EBT3™ film
KW - Inverse square law
KW - Orthovoltage
KW - Quality assurance
UR - http://www.scopus.com/inward/record.url?scp=84938880436&partnerID=8YFLogxK
U2 - 10.1186/s13014-014-0325-0
DO - 10.1186/s13014-014-0325-0
M3 - Article
C2 - 25582565
AN - SCOPUS:84938880436
VL - 10
JO - Radiation oncology (London, England)
JF - Radiation oncology (London, England)
SN - 1748-717X
IS - 1
M1 - 12
ER -