Dose Fidelity and Conformality for High-Dose-Rate Surface Applicator Brachytherapy for Cutaneous...
1
mRem for the general public from continuous or frequent exposure, and 500 mRem from infrequent exposure. Conclusions: Our data show that there is a low level of exposure at the surface, and even lower 35 cm and 100 cm away at the time of implantation and 1 month after brachytherapy. With the NCRP guidelines in mind, we can state conclusively that exposure from permanent Cs-131 brachytherapy for the treatment of brain tumors is limited, and it maintains safe levels of exposure to family and medical personnel. PO54 Dose Fidelity and Conformality for High-Dose-Rate Surface Applicator Brachytherapy for Cutaneous Lymphoma Lesions of the Hands and Feet Phillip M. Devlin, MD, FACR, FASTRO, FFRRCSI (Hon), Sarah Louise St. James, PhD, Allison L. Goddard, MD, Desmond A. O’Farrell, Msc, Ivan Buzurovic, PhD, Scott A. Friesen, MS, Mandar S. Bhagwat, PhD, Thomas Seth Kupper, MD, Robert Alan Cormack, PhD. Brachytherapy, Harvard Medical School, Boston, MA. Purpose: The flexibility and conformality of radiation doses achieved with brachytherapy over highly curvaceous undulating clinical target superficial surfaces is not well documented. In this study we present results achieved Dose fidelity and conformality for High-dose-rate Surface Applicator Brachytherapy for cutaneous lymphoma lesions of the hands and feet using high-dose-rate surface applicator brachytherapy. Materials and Methods: Here is presented a cohort of 6 consecutive patients (8 lesions) with clinically and pathologically proven CTCL lesions of the hands and feet. As these sites of CTCL can be very clinically challenging for both cosmetic and functional endpoints, there is a strong and growing clinical need to have very expedient successful palliative solutions. Whereas it is usually sufficient to use electron fields for flat clinical superficial targets, the conformality of dose over highly curvaceous and undulating surfaces is suboptimal and can lead to clinical failures with attendant consequences. For a cohort of 6 consecutive patients (8 lesions) dose was recorded at the skin surface, 3 mm depth (100%) and the depth of the 50% isodose line across the applicator. Within the Clinical Target Area (CTA) the clinical target volume (CTV) is the volume within the CTA to 3mm in depth. Results: The planned maximum surface dose was less than 125% of the prescribed dose. The 3 mm depth dose was uniformly and conformally 100%. The depth of the 50% was typically within the first centimeters of tissue. Rapid improvement, clinical clearance and minimal to no cutaneous toxicity were observed for all of the lesions. No evidence of recurrence has been observed with after a mean followup of 15.8 months (10.3-23.3 months). Conclusions: This experience highlights the potential of high-dose-rate surface applicator brachytherapy to treat CTCL of the hands and feet. These results warrant further investigation in a multi-institutional environment. The reproduction of this technique relies on minimizing hotspots to the skin surface ( ! 125% prescribed dose) and ensuring uniform coverage of the of the CTV. PROSTATE POSTERS Wednesday - Friday PO55 Prostate Volume Before and After Neoadjuvant Cytoreductive Androgen Suppression and Potential Predictors of Cytoreductive Efficacy Krishan R. Jethwa, BS 1 , Keith M. Furutani, PhD 1 , Lance A. Mynderse, MD 2 , Torrence M. Wilson, MD 2 , Richard C. Choo, MD 1 , Bernard F. King, MD 3 , Eric J. Bergstralh, MS 4 , Brian J. Davis, MD, PhD 1 . 1 Radiation Oncology, Mayo Clinic, Rochester, MN; 2 Urology, Mayo Clinic, Rochester, MN; 3 Diagnostic Radiology, Mayo Clinic, Rochester, MN; 4 Biostatistics, Mayo Clinic, Rochester, MN. Purpose: Limited duration neoadjuvant cytoreductive hormonal therapy (NHT) is used prior to definitive radiotherapeutic management of prostate cancer to decrease target volume and/or decrease urinary symptoms. The purpose of this study is to examine the effect of NHT on prostate volume before permanent prostate brachytherapy (PPB), and determine predictive indictors of prostate volume reduction associated with NHT. Materials and Methods: Between June 1998 and April 2012, 1,110 patients underwent PPB at our institution and provided authorization to access their records for research purposes. A total of 207 patients underwent NHT. Of these, 189 (91.3%) patients underwent transrectal ultrasound (TRUS) before the start of NHT and prior to PPB and detailed measurements of prostate volume were obtained. Mean prostate volume and prostate specific antigen (PSA) were compared before and after NHT. In addition, comparisons were made between those treated with leuprolide or goserelin as well as comparisons between those receiving total androgen suppression (TAS) or luteinizing hormone releasing hormone agonist (LHRHa) alone. Subsequently, pre-treatment variables were analyzed as predictive indicators for prostate volume reduction following NHT. All analyses were performed using JMP version 10, and significance was defined as p ! 0.05. Results: The median duration of NHT was 4.9 months (range, 0.8-23.8 months). The mean prostate volume before NHT was 62.5 22.1 cc (range, 19.0-138.0 cc), and after NHT, it was 37.0 14.5 cc (range, 13.0- 98.0 cc). The mean prostate volume reduction was 23.4 cc (35.9%). There was no significant difference in mean absolute prostate volume reduction between those treated with leuprolide versus goserelin (p50.15), or between those treated with TAS versus LHRHa alone (p50.09). Median PSA before NHT was 6.5 ng/mL (range, 0.7-50.0 ng/mL), and after NHT it was 0.17 ng/mL (range, 0.1-4.4 ng/mL). This resulted in a mean percent PSA reduction of 93.7%. There was no significant difference in mean percent PSA reduction between those treated with leuprolide versus goserelin (p50.36), or between those treated with TAS versus LHRHa alone (p50.30). T-stage, Gleason score, and NCCN risk group were inversely correlated with absolute prostate volume reduction. Multivariate regression found that T-stage and Gleason score accounted for 12% of variance in absolute prostate volume reduction. T-stage was inversely correlated with percent prostate volume reduction, with regression showing T-stage accounting for 2.2% of the variance in percent prostate volume reduction. No correlations were found between prostate volume reduction and patient age or duration of NHT. Conclusion: Neoadjuvant cytoreductive hormonal therapy remains a useful tool in managing patients with enlarged prostates who are otherwise suitable candidates for permanent prostate brachytherapy. Prostate volume decreased by approximately one third after 4.9 months of NHT with a maximum reduction of 63% observed. T-stage and Gleason score may S110 Abstracts / Brachytherapy 13 (2014) S15eS126
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Transcript of Dose Fidelity and Conformality for High-Dose-Rate Surface Applicator Brachytherapy for Cutaneous...
S110 Abstracts / Brachytherapy 13 (2014) S15eS126
mRem for the general public from continuous or frequent exposure, and 500mRem from infrequent exposure.Conclusions: Our data show that there is a low level of exposure at thesurface, and even lower 35 cm and 100 cm away at the time ofimplantation and 1 month after brachytherapy. With the NCRP guidelinesin mind, we can state conclusively that exposure from permanent Cs-131brachytherapy for the treatment of brain tumors is limited, and itmaintains safe levels of exposure to family and medical personnel.
PO54
Dose Fidelity and Conformality for High-Dose-Rate Surface
Applicator Brachytherapy for Cutaneous Lymphoma Lesions of the
Hands and Feet
Phillip M. Devlin, MD, FACR, FASTRO, FFRRCSI (Hon), Sarah Louise St.
James, PhD, Allison L. Goddard, MD, Desmond A. O’Farrell, Msc, Ivan
Buzurovic, PhD, Scott A. Friesen, MS, Mandar S. Bhagwat, PhD, Thomas
Seth Kupper, MD, Robert Alan Cormack, PhD. Brachytherapy, Harvard
Medical School, Boston, MA.
Purpose: The flexibility and conformality of radiation doses achieved withbrachytherapy over highly curvaceous undulating clinical target superficialsurfaces is not well documented. In this study we present results achievedDose fidelity and conformality for High-dose-rate Surface ApplicatorBrachytherapy for cutaneous lymphoma lesions of the hands and feetusing high-dose-rate surface applicator brachytherapy.Materials and Methods: Here is presented a cohort of 6 consecutivepatients (8 lesions) with clinically and pathologically proven CTCLlesions of the hands and feet. As these sites of CTCL can be veryclinically challenging for both cosmetic and functional endpoints, thereis a strong and growing clinical need to have very expedientsuccessful palliative solutions. Whereas it is usually sufficient to useelectron fields for flat clinical superficial targets, the conformality ofdose over highly curvaceous and undulating surfaces is suboptimal andcan lead to clinical failures with attendant consequences. For a cohortof 6 consecutive patients (8 lesions) dose was recorded at the skinsurface, 3 mm depth (100%) and the depth of the 50% isodose lineacross the applicator. Within the Clinical Target Area (CTA) theclinical target volume (CTV) is the volume within the CTA to 3mm indepth.Results: The planned maximum surface dose was less than 125% of theprescribed dose. The 3 mm depth dose was uniformly and conformally100%. The depth of the 50% was typically within the first centimeters oftissue. Rapid improvement, clinical clearance and minimal to nocutaneous toxicity were observed for all of the lesions. No evidence of
recurrence has been observed with after a mean followup of 15.8 months(10.3-23.3 months).Conclusions: This experience highlights the potential of high-dose-ratesurface applicator brachytherapy to treat CTCL of the hands and feet.These results warrant further investigation in a multi-institutionalenvironment. The reproduction of this technique relies on minimizinghotspots to the skin surface (! 125% prescribed dose) and ensuringuniform coverage of the of the CTV.
PROSTATE POSTERS
Wednesday - Friday
PO55
Prostate Volume Before and After Neoadjuvant Cytoreductive
Androgen Suppression and Potential Predictors of Cytoreductive
Efficacy
Krishan R. Jethwa, BS1, Keith M. Furutani, PhD1, Lance A. Mynderse,
MD2, Torrence M. Wilson, MD2, Richard C. Choo, MD1, Bernard F. King,
MD3, Eric J. Bergstralh, MS4, Brian J. Davis, MD, PhD1. 1Radiation
Oncology, Mayo Clinic, Rochester, MN; 2Urology, Mayo Clinic, Rochester,
MN; 3Diagnostic Radiology, Mayo Clinic, Rochester, MN; 4Biostatistics,
Mayo Clinic, Rochester, MN.
Purpose: Limited duration neoadjuvant cytoreductive hormonal therapy(NHT) is used prior to definitive radiotherapeutic management of prostatecancer to decrease target volume and/or decrease urinary symptoms. Thepurpose of this study is to examine the effect of NHT on prostate volumebefore permanent prostate brachytherapy (PPB), and determine predictiveindictors of prostate volume reduction associated with NHT.Materials and Methods: Between June 1998 and April 2012, 1,110patients underwent PPB at our institution and provided authorization toaccess their records for research purposes. A total of 207 patientsunderwent NHT. Of these, 189 (91.3%) patients underwent transrectalultrasound (TRUS) before the start of NHT and prior to PPB and detailedmeasurements of prostate volume were obtained. Mean prostate volumeand prostate specific antigen (PSA) were compared before and after NHT.In addition, comparisons were made between those treated withleuprolide or goserelin as well as comparisons between those receivingtotal androgen suppression (TAS) or luteinizing hormone releasinghormone agonist (LHRHa) alone. Subsequently, pre-treatment variableswere analyzed as predictive indicators for prostate volume reductionfollowing NHT. All analyses were performed using JMP version 10, andsignificance was defined as p! 0.05.Results: The median duration of NHT was 4.9 months (range, 0.8-23.8months). The mean prostate volume before NHT was 62.5 � 22.1 cc(range, 19.0-138.0 cc), and after NHT, it was 37.0 � 14.5 cc (range, 13.0-98.0 cc). The mean prostate volume reduction was 23.4 cc (35.9%). Therewas no significant difference in mean absolute prostate volume reductionbetween those treated with leuprolide versus goserelin (p50.15), orbetween those treated with TAS versus LHRHa alone (p50.09). MedianPSA before NHT was 6.5 ng/mL (range, 0.7-50.0 ng/mL), and after NHTit was 0.17 ng/mL (range, 0.1-4.4 ng/mL). This resulted in a meanpercent PSA reduction of 93.7%. There was no significant difference inmean percent PSA reduction between those treated with leuprolide versusgoserelin (p50.36), or between those treated with TAS versus LHRHaalone (p50.30). T-stage, Gleason score, and NCCN risk group wereinversely correlated with absolute prostate volume reduction. Multivariateregression found that T-stage and Gleason score accounted for 12% ofvariance in absolute prostate volume reduction. T-stage was inverselycorrelated with percent prostate volume reduction, with regressionshowing T-stage accounting for 2.2% of the variance in percent prostatevolume reduction. No correlations were found between prostate volumereduction and patient age or duration of NHT.Conclusion: Neoadjuvant cytoreductive hormonal therapy remains a usefultool in managing patients with enlarged prostates who are otherwise suitablecandidates for permanent prostate brachytherapy. Prostate volumedecreased by approximately one third after 4.9 months of NHT with amaximum reduction of 63% observed. T-stage and Gleason score may
