S14
Poster Presentations
Practical Radiation Oncology: April-June Supplement 2013
low malignancy and complete surgical resection is the primary curative strategy. Long-term follow up is advisable with high 5-year survival rate. The study demonstrated highest positive rate of progesterone receptor (PR), suggesting that progesterone might have played a role in the genesis of SPT.
129
Author Disclosure Block: X. Chengqian: None. X. Zhao: None.
130
See Oral Abstract Presentation #1
See Oral Abstract Presentation #2 125 CT Findings, Clinicopathologic Features, and Treatment Modalities of Anorectal Melanoma: A Report of 10 Cases X. Chengqian, X. Zhao, Cancer Institute and Hospital, Chinese Academy of Medical Sciences, Beijing, China Purpose/Objectives: To retrospectively evaluate CT findings and clinicopathologic features in patients with pathologically proved anorectal melanoma, and to discuss the diagnosis and treatment modalities of this entity. Materials/Methods: Clinicopathologic features, diagnosis, treatment modalities and survival of 10 patients (four men and six women; age range, 41–75 years; mean age, 61 years) with anorectal melanoma in CIAMS from 2006 to 2011, were analyzed. CT scans were evaluated by two radiologists for the involved site, size, morphology, infiltration, lymphadenopathy and metastasis. Results: The most common presentation was rectal bleeding (n = 8), followed by tenesmus (n = 5) and Dyschezia (n = 3). Distant metastasis was noted in 2 patients. The approximate mean length of the tumors was 3.1 cm (range, 1.9-7.7 cm) and the diameter was 2.5 cm (range,1-7 cm). All of the tumors appeared as polypoid or fungating intraluminal neoplasm. Perirectal infiltration could extended to the presacral space (n = 2). 3 patients had lymphadenopathy, involving the perirectal, presacral and iliac vessel lymph node stations. There was no evidence of obstruction in any patients. 6 underwent abdominoperineal resection, 2 underwent local excision, 1 underwent sigmoid colostomy and 1 underwent adjuvant immunotherapy and chemotherapy. Most of the tumors invaded the dentate line confirmed by postoperative pathology (n = 6). All 9 cases stained for HMB-45 and S-100. 8 stained for Melan A. 7 died with the median survival time of 24 months (range, 8–70 months). 1 is undergoing palliative therapy, approaching her end and 2 are under stable condition 21 months and 31 months after surgery. Conclusions: On CT scans, anorectal melanoma appeared as intraluminal fungating masses, expanding the lumen without causing obstruction, with perirectal infiltration and lymphadenopathy. The preoperative staging has an important role in influencing treatment decisions and abdominoperineal resection may be considered as the first choice for the anorectal melanoma patients without distant metastasis. Author Disclosure Block: X. Chengqian: None. X. Zhao: None.
IMAGE GUIDED THERAPEUTIC TECHNIQUES 126 See Oral Abstract Presentation #3
131 See Oral Abstract Presentation #5
132 Dosimetric Impact of Intrafraction Prostate Motion Using a New Contour Shifting Method M.K. Khan 2, S. Shin 1, A. Magnelli 1, P. Xia 1, 1Cleveland Clinic, Cleveland, OH, 2Emory University School of Medicine, Atlanta, GA Purpose/Objectives: To use a newly developed in-house organ contour shifting algorithm to evaluate optimal planning treatment (PTV) margins using daily real-time intra-fraction organ tracking for prostate cancer patients undergoing intensity modulated radiotherapy (IMRT). Materials/Methods: The dose matrices, planning CT images, and physician defined organ contours were exported from the treatment planning system into a new MATLAB algorithm. The new algorithm shifts the prostate organ contours according to real-time intra-fraction prostate tracking data (Calypso® Medical, Seattle, WA). The average prostate motion over each 30 second increment is used to shift the prostate contours within a static dose cloud to generate a composite dose volume histogram (cDVH) for an entire treatment plan (typically 38–39 fractions, each lasting about 10 minutes). The adequacy of the standard PTV margins (6 mm around the prostate and 4 mm posterior to the prostate) was compared against a smaller PTV margin (uniform 2 mm around the prostate). The dose to 90% (D90), 95% (D95), and 99% (D99) of the prostate were compared among the two different treatment margin schemes. Results: Ten patients underwent IMRT (7600–7800 cGy in 38–39 fractions). Most (8) were either intermediate or high risk with six of these patients receiving androgen deprivation therapy. Each patient underwent daily Calypso alignment and prostate tracking during IMRT. The average prostate motion in the Superior-Inferior, Anterior-Posterior, and RightLeft directions were: 0.69 ± 0.8 mm, 0.38 ± 0.8 mm, and 0.11 ± 0.6 mm, respectively. The average magnitude vector was 1.55 ± 0.7 mm. For 6/4 and 2-mm PTV margins, adequate treatment was achieved in 10 out of 10 patients. The percent differences between the 6/4 and 2-mm plans for D90, D95, and D99 were negligible - less than 1.5% in all cases. Conclusions: Our preliminary analysis is consistent with other reports that suggest that 2 mm PTV margins may be adequate with the use of intra-fraction real-time prostate tracking with little impact on the radiation doses delivered. Future work should address the biochemical outcome as well as the reduction in toxicity to surrounding normal organs when reduced PTV margins are employed. Author Disclosure Block: M.K. Khan: None. S. Shin: None. A. Magnelli: None. P. Xia: None.
127 See Oral Abstract Presentation #10 133
128 See Oral Abstract Presentation #6
Use of Implanted Gold Fiducial Markers With MV-CBCT Image Guided IMRT for Pancreatic Tumors M. Packard, A. Kirichenko, O. Gayou, B. Weiss, S. Thakkar, E.D. Werts, Allegheny General Hospital, Pittsburgh, PA
Poster Presentations
Practical Radiation Oncology: April-June Supplement 2013
low malignancy and complete surgical resection is the primary curative strategy. Long-term follow up is advisable with high 5-year survival rate. The study demonstrated highest positive rate of progesterone receptor (PR), suggesting that progesterone might have played a role in the genesis of SPT.
129
Author Disclosure Block: X. Chengqian: None. X. Zhao: None.
130
See Oral Abstract Presentation #1
See Oral Abstract Presentation #2 125 CT Findings, Clinicopathologic Features, and Treatment Modalities of Anorectal Melanoma: A Report of 10 Cases X. Chengqian, X. Zhao, Cancer Institute and Hospital, Chinese Academy of Medical Sciences, Beijing, China Purpose/Objectives: To retrospectively evaluate CT findings and clinicopathologic features in patients with pathologically proved anorectal melanoma, and to discuss the diagnosis and treatment modalities of this entity. Materials/Methods: Clinicopathologic features, diagnosis, treatment modalities and survival of 10 patients (four men and six women; age range, 41–75 years; mean age, 61 years) with anorectal melanoma in CIAMS from 2006 to 2011, were analyzed. CT scans were evaluated by two radiologists for the involved site, size, morphology, infiltration, lymphadenopathy and metastasis. Results: The most common presentation was rectal bleeding (n = 8), followed by tenesmus (n = 5) and Dyschezia (n = 3). Distant metastasis was noted in 2 patients. The approximate mean length of the tumors was 3.1 cm (range, 1.9-7.7 cm) and the diameter was 2.5 cm (range,1-7 cm). All of the tumors appeared as polypoid or fungating intraluminal neoplasm. Perirectal infiltration could extended to the presacral space (n = 2). 3 patients had lymphadenopathy, involving the perirectal, presacral and iliac vessel lymph node stations. There was no evidence of obstruction in any patients. 6 underwent abdominoperineal resection, 2 underwent local excision, 1 underwent sigmoid colostomy and 1 underwent adjuvant immunotherapy and chemotherapy. Most of the tumors invaded the dentate line confirmed by postoperative pathology (n = 6). All 9 cases stained for HMB-45 and S-100. 8 stained for Melan A. 7 died with the median survival time of 24 months (range, 8–70 months). 1 is undergoing palliative therapy, approaching her end and 2 are under stable condition 21 months and 31 months after surgery. Conclusions: On CT scans, anorectal melanoma appeared as intraluminal fungating masses, expanding the lumen without causing obstruction, with perirectal infiltration and lymphadenopathy. The preoperative staging has an important role in influencing treatment decisions and abdominoperineal resection may be considered as the first choice for the anorectal melanoma patients without distant metastasis. Author Disclosure Block: X. Chengqian: None. X. Zhao: None.
IMAGE GUIDED THERAPEUTIC TECHNIQUES 126 See Oral Abstract Presentation #3
131 See Oral Abstract Presentation #5
132 Dosimetric Impact of Intrafraction Prostate Motion Using a New Contour Shifting Method M.K. Khan 2, S. Shin 1, A. Magnelli 1, P. Xia 1, 1Cleveland Clinic, Cleveland, OH, 2Emory University School of Medicine, Atlanta, GA Purpose/Objectives: To use a newly developed in-house organ contour shifting algorithm to evaluate optimal planning treatment (PTV) margins using daily real-time intra-fraction organ tracking for prostate cancer patients undergoing intensity modulated radiotherapy (IMRT). Materials/Methods: The dose matrices, planning CT images, and physician defined organ contours were exported from the treatment planning system into a new MATLAB algorithm. The new algorithm shifts the prostate organ contours according to real-time intra-fraction prostate tracking data (Calypso® Medical, Seattle, WA). The average prostate motion over each 30 second increment is used to shift the prostate contours within a static dose cloud to generate a composite dose volume histogram (cDVH) for an entire treatment plan (typically 38–39 fractions, each lasting about 10 minutes). The adequacy of the standard PTV margins (6 mm around the prostate and 4 mm posterior to the prostate) was compared against a smaller PTV margin (uniform 2 mm around the prostate). The dose to 90% (D90), 95% (D95), and 99% (D99) of the prostate were compared among the two different treatment margin schemes. Results: Ten patients underwent IMRT (7600–7800 cGy in 38–39 fractions). Most (8) were either intermediate or high risk with six of these patients receiving androgen deprivation therapy. Each patient underwent daily Calypso alignment and prostate tracking during IMRT. The average prostate motion in the Superior-Inferior, Anterior-Posterior, and RightLeft directions were: 0.69 ± 0.8 mm, 0.38 ± 0.8 mm, and 0.11 ± 0.6 mm, respectively. The average magnitude vector was 1.55 ± 0.7 mm. For 6/4 and 2-mm PTV margins, adequate treatment was achieved in 10 out of 10 patients. The percent differences between the 6/4 and 2-mm plans for D90, D95, and D99 were negligible - less than 1.5% in all cases. Conclusions: Our preliminary analysis is consistent with other reports that suggest that 2 mm PTV margins may be adequate with the use of intra-fraction real-time prostate tracking with little impact on the radiation doses delivered. Future work should address the biochemical outcome as well as the reduction in toxicity to surrounding normal organs when reduced PTV margins are employed. Author Disclosure Block: M.K. Khan: None. S. Shin: None. A. Magnelli: None. P. Xia: None.
127 See Oral Abstract Presentation #10 133
128 See Oral Abstract Presentation #6
Use of Implanted Gold Fiducial Markers With MV-CBCT Image Guided IMRT for Pancreatic Tumors M. Packard, A. Kirichenko, O. Gayou, B. Weiss, S. Thakkar, E.D. Werts, Allegheny General Hospital, Pittsburgh, PA
