- Email: [email protected]
Spatial dose-mapping following transperineal interstitial permanent prostate brachytherapy
148
I. J. Radiation
Oncology
l Biology
l Physics
Volume 4X, Number 3. Supplement,
2000
lateral, left postero-lateral, posterior, right poatero-lateral and right lateral locations were as follows: 5.4 ? 19 (0-14mm), 4.X -t 2.61 (O-13), 3.3 2 2.08 (O-13) 5.2 ? 2.3 (o-15). 6.1 IT 2.0 (O-13), respectively. The posterior extraprostatic coverage was the smallest, and reflects an attempt to limit the amount of rectal mucosa that received the prescription dose. Conclusion: Our results suggest that prostate brachytherapy using Pd.103 can deliver the prescription dose approximately 3-S mm beyond the gland, especially in the postero-lateral aspects of the gland where EPE is most often noted. The post-implant dosimetry reflects the intent to treat potential EPE. Our data does not support possible concerns that monotherapy with a lower energy isotope may not fully address potential EPE. We hope this work will stimulate other investigators to analyze their post-implant CT scans to confirm these results.
73
Spatial dose-mapping
B. R. Prestidge,‘.’
W. S. Bite,‘.’
following transperineal E. S. Walker,’
interstitial
permanent
prostate bracbytherapy
M. F. Sarosdy”
‘Texas Prostate Brtrchytherqy Sen?ces, Sm Atltonio, TX “Ctrncer Thrrcpv Rusmrch Center, San Antonio, TX ‘University of Texas Health S&nrr Center, San AlltoGo, TX, ‘South Tatr.s Urology md Urologic Oncology, Sarr Antonio, TX Purpose: The dosimetric description of dose delivered to the prostate following transperineal interstitial permanent prostate brachytherapy has been shown to be of critical importance for documentation, improving technique. and in some cases determining the need for additional therapies. Although the dose-volume histogram (DVH) is helpful in roughly describing dose coverage, it does not address the geographic distribution of dose within the gland. We describe a novel method of evaluating and presenting this spatial dose information for prostate brachytherapy and have applied it to a series of patients. Materials/Methods: The post-implant dosimetry of a series of 118 unselected patients receiving prostate brachytherapy with Pd-103 (93) and I-125 (25) for low to intermediate risk prostatic carcinoma were analyzed. The prostate was divided into 12 sectors centered about the urethra. This included four sectors each at the base, mid-gland, and apex, such that sector 1 included the anterior base. sector 2 the right base, sector 3 the posterior base, and sector 4 the left base. Sectors 5-X and 9-l 2 cover the mid-gland and apex in a similar fashion. Each sector was then subjected to DVH analysis, allowing comparison by sector between implants. isotopes, applicator technique, and various other parameters. V,,,,,. the percentage of the gland covered by at least the prescription dose, and D,,,. the dose at which 90% of the gland is covered by this dose or greater, were calculated for the prostate and for each sector. These values were statistically compared between sets of implants using Student’s t-test. Results: The V,,,,, and 7cD,,,. D,,, expressed as a percentage of the prescription dose, for all patients was 97.2 -t 2.8% and 145 ? 34.3%, respectively. A compiled sector analysis for all implants showed that the regions receiving the lowest doses were sectors I (antbase), with V,,,,, of 9176%. and I1 (post apex), 94.3%~. A table depicting the results of the sector analysis for Vi,,, is shown in the Table. Statistically better dose coverage was noted for I- 125 (vs Pd- 103) p = ,002, preloaded needles (vs Mick applicator) p = ,003, and boost patients (vs monotherapy) p = .026. Conclusion: The data reported here are a reflection of our planning philosophy, intraoperative technique, and experience and are unique to our program. Sector analysis provides the vital element of spatial distribution, or ‘dose-mapping’ within the prostate. This method can he employed to address imperfections in technique that may be systematic to a given prostate brachytherapy program thus providing the specific feedback information necessai-y to improve in implant quality, even among experienced practitioners.
SectorI Sector Sector Sector sector Sector Sector Sector Sector Sector Sector
2 3 1 s 6 I 8 9 IO
II SectorI2 Ovcrell
74
Y8.1’;
918%
98.9%
95.9%
Y7.1%
93.5%,
YY.3%
Y7.0%
99.8%
93.6%
90.3%
0. 14
919%
94.5%
97.0%
94.3%
0.05
95.4%
97.7%
0.01
95.7%
86.3%
93.X%,
94.8%
0.03
0.01
Y7.4%
97.6%
0.08
0 I4
9X .O%
99.8%
9Y.X%
0.40
99.3%
100.0%
‘)X.6%
I 0.02 0.04 0.03 0. 15
100.0%
99.6%
0.09
90.7%
0.0
98.1% ‘)X.6%
94. I ‘X 100.0%
I
0.08
0.07
99.9%
99.6%,
0.1-I
99.7%
99.4%
0.13
99.5%
99.9%
0.02
99.5%
99.7%
0.3.5
99.7%’
99.6%
0.42
9Y .I%’
99,‘)s
0.01
99.7%
96.3’Z
0.06
96.7%
98.7%
0.20
95.6%
98.7%’
0.07
99.9%
97.8%
0.04
98.1%
98.8%’
0.2x
‘JX.O%
‘)X.5%’
0.02
Y8.OTf
94.m
0.03
95.7%
YlS%
0.03
Y4.0%
Yh.l%
0.0’)
99.4??
97.3%
0.03
97.6’1
98.7%’
0.19
Y6.7’X
‘)‘).I%
0.02
99.
96.8%
0.002
97.6%
Y5.2%’
0.003
Y6 7%
97.94
0.026
I%
What is the optimal dose for I-125 prostate implants? A dose response analysis of long-term urinary symptoms, biochemical control and post-treatment biopsy
R. G. Stock, N. N. Stone, M. Dalal. Y. C. Lo
Mount Sinai School of Medicinr, New York, NY Objective: To define the optimal dose for I-l 25 prostate implants biochemical failure and post-treatment biopsies.
by correlating
doaimetry
findings with urinary
symptoms,
Materials and Methods: This analysis consisted of patients with Tl-T2. Gleason score 2-6 prostate cancer who underwent I-125 prostate seed implantation without external beam irradiation followed by one month CT based post-implant dosimetry. Group 1 (276 patients, follow-up: 18 to 108 months (median 34)) had urinary symptoms prospectively assessed using the IPSS symptom scoring system. Group 2 (180patients, follow-up: 24 to 108 months (median 44), presenting PSA: 0.3 - 189 (median-
I. J. Radiation
Oncology
l Biology
l Physics
Volume 4X, Number 3. Supplement,
2000
lateral, left postero-lateral, posterior, right poatero-lateral and right lateral locations were as follows: 5.4 ? 19 (0-14mm), 4.X -t 2.61 (O-13), 3.3 2 2.08 (O-13) 5.2 ? 2.3 (o-15). 6.1 IT 2.0 (O-13), respectively. The posterior extraprostatic coverage was the smallest, and reflects an attempt to limit the amount of rectal mucosa that received the prescription dose. Conclusion: Our results suggest that prostate brachytherapy using Pd.103 can deliver the prescription dose approximately 3-S mm beyond the gland, especially in the postero-lateral aspects of the gland where EPE is most often noted. The post-implant dosimetry reflects the intent to treat potential EPE. Our data does not support possible concerns that monotherapy with a lower energy isotope may not fully address potential EPE. We hope this work will stimulate other investigators to analyze their post-implant CT scans to confirm these results.
73
Spatial dose-mapping
B. R. Prestidge,‘.’
W. S. Bite,‘.’
following transperineal E. S. Walker,’
interstitial
permanent
prostate bracbytherapy
M. F. Sarosdy”
‘Texas Prostate Brtrchytherqy Sen?ces, Sm Atltonio, TX “Ctrncer Thrrcpv Rusmrch Center, San Antonio, TX ‘University of Texas Health S&nrr Center, San AlltoGo, TX, ‘South Tatr.s Urology md Urologic Oncology, Sarr Antonio, TX Purpose: The dosimetric description of dose delivered to the prostate following transperineal interstitial permanent prostate brachytherapy has been shown to be of critical importance for documentation, improving technique. and in some cases determining the need for additional therapies. Although the dose-volume histogram (DVH) is helpful in roughly describing dose coverage, it does not address the geographic distribution of dose within the gland. We describe a novel method of evaluating and presenting this spatial dose information for prostate brachytherapy and have applied it to a series of patients. Materials/Methods: The post-implant dosimetry of a series of 118 unselected patients receiving prostate brachytherapy with Pd-103 (93) and I-125 (25) for low to intermediate risk prostatic carcinoma were analyzed. The prostate was divided into 12 sectors centered about the urethra. This included four sectors each at the base, mid-gland, and apex, such that sector 1 included the anterior base. sector 2 the right base, sector 3 the posterior base, and sector 4 the left base. Sectors 5-X and 9-l 2 cover the mid-gland and apex in a similar fashion. Each sector was then subjected to DVH analysis, allowing comparison by sector between implants. isotopes, applicator technique, and various other parameters. V,,,,,. the percentage of the gland covered by at least the prescription dose, and D,,,. the dose at which 90% of the gland is covered by this dose or greater, were calculated for the prostate and for each sector. These values were statistically compared between sets of implants using Student’s t-test. Results: The V,,,,, and 7cD,,,. D,,, expressed as a percentage of the prescription dose, for all patients was 97.2 -t 2.8% and 145 ? 34.3%, respectively. A compiled sector analysis for all implants showed that the regions receiving the lowest doses were sectors I (antbase), with V,,,,, of 9176%. and I1 (post apex), 94.3%~. A table depicting the results of the sector analysis for Vi,,, is shown in the Table. Statistically better dose coverage was noted for I- 125 (vs Pd- 103) p = ,002, preloaded needles (vs Mick applicator) p = ,003, and boost patients (vs monotherapy) p = .026. Conclusion: The data reported here are a reflection of our planning philosophy, intraoperative technique, and experience and are unique to our program. Sector analysis provides the vital element of spatial distribution, or ‘dose-mapping’ within the prostate. This method can he employed to address imperfections in technique that may be systematic to a given prostate brachytherapy program thus providing the specific feedback information necessai-y to improve in implant quality, even among experienced practitioners.
SectorI Sector Sector Sector sector Sector Sector Sector Sector Sector Sector
2 3 1 s 6 I 8 9 IO
II SectorI2 Ovcrell
74
Y8.1’;
918%
98.9%
95.9%
Y7.1%
93.5%,
YY.3%
Y7.0%
99.8%
93.6%
90.3%
0. 14
919%
94.5%
97.0%
94.3%
0.05
95.4%
97.7%
0.01
95.7%
86.3%
93.X%,
94.8%
0.03
0.01
Y7.4%
97.6%
0.08
0 I4
9X .O%
99.8%
9Y.X%
0.40
99.3%
100.0%
‘)X.6%
I 0.02 0.04 0.03 0. 15
100.0%
99.6%
0.09
90.7%
0.0
98.1% ‘)X.6%
94. I ‘X 100.0%
I
0.08
0.07
99.9%
99.6%,
0.1-I
99.7%
99.4%
0.13
99.5%
99.9%
0.02
99.5%
99.7%
0.3.5
99.7%’
99.6%
0.42
9Y .I%’
99,‘)s
0.01
99.7%
96.3’Z
0.06
96.7%
98.7%
0.20
95.6%
98.7%’
0.07
99.9%
97.8%
0.04
98.1%
98.8%’
0.2x
‘JX.O%
‘)X.5%’
0.02
Y8.OTf
94.m
0.03
95.7%
YlS%
0.03
Y4.0%
Yh.l%
0.0’)
99.4??
97.3%
0.03
97.6’1
98.7%’
0.19
Y6.7’X
‘)‘).I%
0.02
99.
96.8%
0.002
97.6%
Y5.2%’
0.003
Y6 7%
97.94
0.026
I%
What is the optimal dose for I-125 prostate implants? A dose response analysis of long-term urinary symptoms, biochemical control and post-treatment biopsy
R. G. Stock, N. N. Stone, M. Dalal. Y. C. Lo
Mount Sinai School of Medicinr, New York, NY Objective: To define the optimal dose for I-l 25 prostate implants biochemical failure and post-treatment biopsies.
by correlating
doaimetry
findings with urinary
symptoms,
Materials and Methods: This analysis consisted of patients with Tl-T2. Gleason score 2-6 prostate cancer who underwent I-125 prostate seed implantation without external beam irradiation followed by one month CT based post-implant dosimetry. Group 1 (276 patients, follow-up: 18 to 108 months (median 34)) had urinary symptoms prospectively assessed using the IPSS symptom scoring system. Group 2 (180patients, follow-up: 24 to 108 months (median 44), presenting PSA: 0.3 - 189 (median-