Cobalt 60 versus 15 MeV photons during total body irradiation: doses in the critical organs and complexicity of the procedure.
OBJECTIVE
The aim of this work was to compare the doses in critical organs, treatment duration, patient comfort and personnel workload during total body irradiation carried out alternatively with a Cobalt 60 and with 15 MeV photons at linear accelerator.


METHODS
Twenty consecutive patients irradiated with a Cobalt unit and twenty irradiated with 15 MeV photons in a linear accelerator were used for comparison of the dose delivered. Each irradiation was repeated eight times during four consecutive days up to a total dose of 12.6 Gy in the whole body (below 10 Gy in the lungs). Lateral fields were used in six fractions, and anterior-posterior fields in two fractions. An electron boost to the thorax wall was added. Doses were calculated and measured in-vivo in ten transverse sections.


RESULTS
For the patient taken as an example doses in the middle of the lungs were 10.7 Gy for Co-60 and 11.2 Gy for 15 MeV photons without compensators and 9.6 Gy, 9.6 Gy respectively when compensators were applied. Mean doses in the lungs in the group were 9.5 Gy for Co-60 and 9.7 Gy for X 15 MeV, respectively. Duration of the treatment was shorter with the use of the 15 MeV than that with Co-60 by about 20%. Repositioning of the patient during two fractions with the use of X 15 MeV could be eliminated and therefore the patient's comfort increased.
Malicki
J
J
Greatpoland Cancer Centre, Poznań, Poland. Malicki@wco.pl
Kosicka
G
G
Stryczyńska
G
G
Wachowiak
J
J
D003037:Cobalt Radioisotopes; D006801:Humans; D007165:Immunosuppression Therapy / Q000379:methods*; D008168:Lung / Q000528:radiation effects; D010315:Particle Accelerators; D017785:Photons; D011835:Radiation Protection / Q000379:methods; D011879:Radiotherapy Dosage; D014916:Whole-Body Irradiation / Q000379:methods*
D003037:Cobalt Radioisotopes