A pilot comparison study of setup verification between two-dimensional kilo-voltage (2DkV) matchand kilo-voltage cone-beam computed tomography (kV-CBCT) match for nasopharyngeal cancer patients.

Objective: Setup verification is the critical part to make sure of the accuracy for Intensity-modulated radiotherapy in nasopharyngeal cancer patients. This pilot study was designed to answer whether and how much the kV-CBCT in addition to 2DkV is more accurate than 2DkV alone in terms of verification parameters. Methods: Images acquisition: Offline images were displayed in the matched position between reference images. 2D and 3D matches: The bony matches were done by using the location of the tumor in the nasopharyngeal and upper neck regions. The distances displaced from the isocenter were recorded in x-y-z directions. Analysis: The distance of the isocenter shift in each direction (X, Y, Z) were presented as point estimations. The alignment between the two methods was assessed with Pearson’s and Spearman’s correlation. The 3 mm difference within 90% is considered as an acceptable range of non-inferiority of 2DkV, compared with CBCT. Results: 11 nasopharyngeal cancer patients were included into this study. The correlation between 2DkV and kV-CBCT were 0.46, 0.11 and 0.16 for Superior-inferior (SI), Anterior-posterior (AP) and Left-right (LR) directions, respectively. The central value for the kV-CBCT; SI, AP and LR directional shift were 0.07, 0.06 and 0.03 cm, respectively, whereas the central value for 2DkV; SI, AP and LR directional shift were 0.05, 0.07 and 0.04 cm. For the difference shift < 3 mm, the results > 90% were within acceptable value: 100% and 96.96% for SI and LR directions whereas the AP direction was 87.87%. Conclusion: Compared with kV-CBCT by using our criteria, 2DkV images are accurate enough for treatment verification in nasopharyngeal cancer patients.

Preliminary result of using intensity modulated radiation therapy (IMRT) as a primary treatment for prostate cancer at Siriraj Hospital in Thailand: toxicity and biochemical outcomes.

Objective: This study is a retrospective study of the outcome and the incidence of the toxicity of using intensity-modulated radiation therapy (IMRT) as the primary treatment for prostate cancer at Siriraj Hospital. Methods: Hospital records and radiotherapy medical records of prostate cancer patients treated with IMRT as the primary treatment between July 2004 and May 2009 at Siriraj Hospital were all reviewed. Seventy-five prostate cancer patients were included in the study. Patient’s biochemical failure was established at the time of prostatic specific antigen progression above the post-treatment nadir value +2 ng/ml according to the Phoenix definition. Acute and Late toxicity were assessed and scored according to the Radiotherapy Oncology Group grading system. Results: The median follow up time was 25 months (range 3 – 63 months). The two years overall survival (OS) and freedom from biochemical failure rate (FFBF) were 93.7 and 95.8%, respectively. Five patients (6.6%) developed prostatic specific antigen failure according to the Phoenix definition. The incidences of grade  2 of acute and late gastrointestinal toxicity were 12% and 2.7%, respectively. The incidences of grade  2 of acute and late genito-urinary toxicity were 61.3% and 41.3%, respectively. Conclusion: This preliminary result of using IMRT as the primary treatment for prostate cancer provides good outcomes. The FFBF and OS are comparable with other studies. The incidences of acute and late gastrointestinal toxicity are acceptable, but the incidences of acute and late genito-urinary toxicity are higher than other studies.