Intensity-modulated radiation therapy: not a dry eye in the house.
Inverse planned intensity-modulated radiation therapy (IMRT) has been applied to patients in a conformal fashion in order to avoid the lacrimal gland. In the present study, we report a patient in which a potential planned dose of 63 Gy to the lacrimal gland for a conventional plan was reduced to 12 Gy to the lacrimal gland for the IMRT plan. Dose objective inverse planning was provided using a Pinnacle treatment planning computer and treatment was delivered using a Varian dynamic multileaf collimator (MLC) on a Varian linear accelerator. Because multiple MLC segments are used to deliver the modulated treatment, conventional dose checks by manual calculation are not practical. To aid in an alternative dosimetric verification process, the Pinnacle planning computer has two unique dose tools, which provide axial and beams eye view doses on user-specified check phantoms. The combined field axial dose tool matched our ion chamber dose checks within +/- 2.4% at the isocentre. The individual beams eye view dose tool matched film dose maps within +/- 3% in the umbra.
Metcalfe
Peter
P
Illawarra Cancer Care Centre, Wollongong University, New South Wales, Australia. metcalfep@iahs.nsw.gov.au
Chapman
Alison
A
Arnold
Anthony
A
Arnold
Belinda
B
Tangboonduangjit
Puangpeng
P
Capp
Anne
A
Fox
Chris
C
D000368:Aged; D002294:Carcinoma, Squamous Cell / Q000532:radiotherapy* / Q000556:secondary; D005138:Eyebrows; D005153:Facial Neoplasms / Q000532:radiotherapy*; D006801:Humans; D007765:Lacrimal Apparatus / Q000293:injuries / Q000528:radiation effects; D008297:Male; D011832:Radiation Injuries / Q000517:prevention & control; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods; D020266:Radiotherapy, Conformal / Q000379:methods; D012160:Retina / Q000293:injuries / Q000528:radiation effects; D012878:Skin Neoplasms / Q000532:radiotherapy*