Verification of the dose distribution for 192Ir mould treatments using radiochromic film and LiF:Mg,Cu,P TLDs.
Radioactive moulds are an effective way of treating skin lesions. The aim of the study was to verify the dose distribution in a low dose rate 192Ir hand mould treatment using radiochromic film and LiF:Mg,Cu,P TLDs. Measurements were compared with two computerised treatment planning systems--Theraplan VO5B and ADAC Pinnacle3 V4.0b. Radiochromic film measured doses that were typically 25-30% lower than the TLD and planning computer doses (which agreed within +/- 5%). However, radiochromic film provided a two-dimensional map, which is particularly useful for dose distributions that are difficult to predict. This was demonstrated in the effects of adding thumb shielding to the hand mould. TLD results provided only point dose verification. Dose rates to the inner surface of the thumb were reduced from 15-20 cGy/hr to 2-4 cGy/hr by using 7.5 mm lead shielding. This is consistent with three half value layer reductions. For unshielded treatments, TLD results agreed with the treatment planning computers all within +/- 13%, including an uncertainty of +/- 10% on the source strength certificate for the activity. Due to the detector's sensitivity, miniaturisation would be the next approach for further more accurate verification with LiF:Mg,Cu,P TLDs.
Newcastle Mater Misercordiae Hospital, Waratah, Australia.
L
L
Duggan
M
M
Butson
S
S
Howlett
J
J
Denham
T
T
Kron
D001918:Brachytherapy / Q000379:methods*; D006225:Hand; D006801:Humans; D007496:Iridium Radioisotopes / Q000627:therapeutic use*; D011880:Radiotherapy Planning, Computer-Assisted; D012878:Skin Neoplasms / Q000532:radiotherapy; D013819:Thermoluminescent Dosimetry; D014962:X-Ray Film
D007496:Iridium Radioisotopes