Purpose: To test the concept of Statistical Process Control (SPC) as a Quality
Assurance (QA) procedure for dose verifications in external beam radiation therapy in conventional and 3D Conformal
Radiotherapy (3D-CRT) treatment of cervical cancer. Materials and
Methods: A study of QA verification of
target doses of 198 cervical cancer patients undergoing External Beam Radiotherapy (EBRT) treatments at two different
cancer treatment centers in Kenya was
conducted. The target doses were determined from measured entrancedoses by the diode in vivo dosimetry. Process Behavior
Charts (PBC) developed by SPC were applied for setting Action
Thresholds (AT) on the target doses. The AT set was then
proposed as QA limits for acceptance or rejection of verified target doses overtime of the EBRT process. Result and Discussion:Target
doses for the 198 patients were calculated and SPC applied to test whether the action limits set by the
Process Behavior Charts could be applied as QA for verified doses in
EBRT. Results for the two sub-groups of n=3 and n=4 that were tested produced action thresholds which
are within clinical dose
specifications for both conventional AP/PA and 3D-CRT EBRT treatment
techniques for cervical cancer. Conclusion: Action thresholds set by SPC were within the clinical dose specification of ±5% uncertainty for both conventional
AP/PAand 3D-CRT EBRT treatment
techniques for cervical cancer. So the concept of SPC could be applied
in setting QA
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