Matched-pair analysis and dosimetric variations of two types of software for interstitial permanent brachytherapy for prostate cancer.

The purpose of this study was to determine whether identical dosimetric results could be achieved using different planning software for permanent interstitial brachytherapy for prostate cancer. Data from 492 patients treated with brachytherapy were used for matched-pair analysis. Interplant and Variseed were used as software for ultrasound-based treatment planning. Institution, neoadjuvant hormonal therapy, prostate volume, and source strength were used for factors to match the 2 groups. The study population comprised of 126 patients with treatment planning using Interplant software and 127 matched patients using Variseed software. Dosimetric results were compared between the 2 groups. The Variseed group showed significantly higher values for dose covering 90% of prostate volume (pD90), prostate volume covered by 150% of prescription dose (pV150), and dose covering 30% of the urethra (uD30) compared with the Interplant group. Our results showed that use of different software could lead to different dosimetric results, which might affect the clinical outcomes.

Differences between intraoperative ultrasound-based dosimetry and postoperative computed tomography-based dosimetry for permanent interstitial prostate brachytherapy.

PURPOSE: To compare the results of intraoperative ultrasound (US)-based dosimetry with those of postimplant computed tomography (CT)-based dosimetry after (125)I prostate brachytherapy. METHODS AND MATERIALS: Subjects comprised 160 patients who underwent prostate brachytherapy using (125)I seed implants. Prescribed dose was set as 145 Gy to the periphery of the prostate. Implantation was performed using an intraoperative interactive technique. Postimplant dosimetry was performed on Days 1 and 30 after implantation using CT. Dosimetric results for the prostate, urethra, and rectum were compared among intraoperative US and CT on Day 1 (CT(1)) and Day 30 (CT(30)). RESULTS: Mean minimal dose received by 90% of prostate volume was 133.7%, 115.6%, and 125.8% of the prescribed dose on US, CT(1), and CT(30), respectively: This value temporarily decreased on Day 1 and increased on Day 30. Other parameters for the prostate and urethra showed similar trends. Conversely, mean rectal volume receiving 100% of the prescribed dose was 0.69, 0.46, and 1.02 mL on US, CT(1), and CT(30), respectively. Rectal parameters tended to be underestimated on US relative to CT(30)-based dosimetry. A positive linear relationship was identified between US and CT observations for every prostate parameter and the dose covering 30% of the urethra. CONCLUSIONS: Our results demonstrate significant differences between dosimetric parameters obtained by US, CT(1), and CT(30). However, significant correlations also exist between US and CT, at least in prostate and urethral parameters. Clarification of the degrees of difference might make US planning more feasible.

Cost comparison of curative therapies for localized prostate cancer in Japan: a single-institution experience.

PURPOSE: In addition to open surgery, curative therapies for prostate cancer now include endoscopic surgery and radiation therapies. Because of the expansion and subdivision of treatment methods for prostate cancer, the medical fee point schedule in Japan was revised in fiscal year 2006. We examined changes in medical income and expenditure after this revision of the medical fee system. MATERIALS AND METHODS: We studied income and expenditure, after institution of the new medical fee schedule, for the five types of therapies for prostate cancer performed at our hospital: two surgical therapies (radical retropubic prostatectomy and laparoscopic prostatectomy) and three radiation therapies (three-dimensional conformal radiation therapy, (192)Ir high-dose-rate brachytherapy, and (125)I low-dose-rate brachytherapy). RESULTS: Low-dose-rate brachytherapy was found to be associated with a profit of yen199 per patient. Laparoscopic prostatectomy, a highly advanced medical treatment that the fee revision changed from a partially insured to an insured procedure, yielded a profit of yen75,672 per patient. However, high-dose-rate brachytherapy was associated with a loss of yen654,016 per patient. CONCLUSION: Given the loss in hospital income per patient undergoing high-dose-rate brachytherapy, the medical fee point system for this procedure should be reassessed.

Genitourinary toxicity after high-dose-rate (HDR) brachytherapy combined with Hypofractionated External beam radiotherapy for localized prostate cancer: an analysis to determine the correlation between dose-volume histogram parameters in HDR brachytherapy and severity of toxicity.

PURPOSE: To evaluate the severity of genitourinary (GU) toxicity in high-dose-rate (HDR) brachytherapy combined with hypofractionated external beam radiotherapy (EBRT) for prostate cancer and to explore factors that might affect the severity of GU toxicity. METHODS AND MATERIALS: A total of 100 Japanese men with prostate cancer underwent (192)Ir HDR brachytherapy combined with hypofractionated EBRT. Mean (SD) dose to 90% of the planning target volume was 6.3 (0.7) Gy per fraction of HDR. After 5 fractions of HDR treatment, EBRT with 10 fractions of 3 Gy was administrated. The urethral volume receiving 1-15 Gy per fraction in HDR brachytherapy (V1-V15) and the dose to at least 5-100% of urethral volume in HDR brachytherapy (D5-D100) were compared between patients with Grade 3 toxicity and those with Grade 0-2 toxicity. Prostate volume, patient age, and International Prostate Symptom Score were also compared between the two groups. RESULTS: Of the 100 patients, 6 displayed Grade 3 acute GU toxicity, and 12 displayed Grade 3 late GU toxicity. Regarding acute GU toxicity, values of V1, V2, V3, and V4 were significantly higher in patients with Grade 3 toxicity than in those with Grade 0-2 toxicity. Regarding late GU toxicity, values of D70, D80, V12, and V13 were significantly higher in patients with Grade 3 toxicity than in those with Grade 0-2 toxicity. CONCLUSIONS: The severity of GU toxicity in HDR brachytherapy combined with hypofractionated EBRT for prostate cancer was relatively high. The volume of prostatic urethra was associated with grade of acute GU toxicity, and urethral dose was associated with grade of late GU toxicity.

Interactive-plan technique conquers the disadvantages of volume-reducing hormone therapy in 125I permanent implantation for localized prostate cancer.

BACKGROUND: The purpose of this study was to assess the impact of hormone therapy on post-implant dosimetry in patients in whom pre-plan and interactive-plan techniques were used for transperineal brachytherapy against prostatic cancer. METHODS: The subjects comprised 244 patients treated using (125)I seed implantation as monotherapy. The prescribed dose to the periphery of the prostate was 145 Gy. The pre-plan technique was used for 116 patients, and the interactive-plan technique for 128 patients. Hormone therapy was used in 71 patients (29.1%). The D90 (dose to 90% of prostate volume) of post-implant computed tomography (CT) analysis was assessed in both groups. In addition, the ratio of post-implant CT volume to preoperative ultrasonography (US) volume was assessed. RESULTS: In the pre-plan group, D90 was significantly lower for patients who received hormone therapy than for those who did not (P = 0.035). However, in the interactive-plan group, D90 did not differ between patients with and without hormone therapy (P = 0.467). The CT-to-US prostate volume ratio was 1.022 for patients who received hormone therapy and 0.960 for patients who did not (P = 0.021). CONCLUSION: Post-traumatic swelling following implantation is increased by cessation of hormone therapy and may reduce D90. However, the present results suggest that the interactive-plan technique overcomes this disadvantage of hormone therapy.

Needle position during (125)I seed implantation: accurately recognized by sagittal transrectal ultrasonography [corrected].

PURPOSE: The aim of this study was to assess the variation of probe rotation angles for detecting a single needle using sagittal images of transrectal ultrasonography (TRUS). MATERIALS AND METHODS: A phantom study was performed. One needle was inserted through each of 10 holes of the template, and variations in the probe rotation angles for detecting the needle were measured. RESULTS: The mean variation of probe rotation for detecting a single needle was 17.0 degrees (range 4 degrees -25 degrees ). Slightly broader variation was seen for the needle in holes farther away from the probe. CONCLUSION: Probe rotation angles for detecting a single needle displayed considerable variation. Seed locations recognized on sagittal imaging by TRUS are thus indeterminate, and real-time dose calculations using TRUS for (125)I seed implantation should be used with care.

Inter-software variability in post-implanted CT analysis for interstitial permanent brachytherapy for prostate cancer: differences in automatically detected seed location.

Purpose. The present study investigated inter-software variability in automatically detected seed location and dose volume histogram (DVH). Materials and methods. Image sets from computed tomography (CT) of 25 patients treated using interstitial permanent brachytherapy were examined. Interplant and Variseed were used as software for post-implanted CT analysis. Seed locations are automatically detected by Variseed and Interplant. Dose-volume histograms were calculated using seed locations as detected by the two programs. DVH parameters were compared between Variseed and Interplant. Results. Considerable differences in DVH parameters existed between Variseed and Interplant. For example, mean differences in dose to 90% of prostate volume (pD90) and dose to 5% of urethral volume (uD5) were 8.27 Gy and 20.18 Gy, respectively. The difference in uD5 was associated with prostate volume. Conclusion. Our results suggest that considerable inter-software variability exists in post-implanted CT analysis. DVH parameters from other software should be used with care.

Four-year experience of interstitial permanent brachytherapy for Japanese men with localized prostate cancer.

OBJECTIVE: To report 4 year results obtained with our initial 100 patients with localized prostate cancer treated by interstitial permanent brachytherapy. METHODS: One-hundred Japanese men with clinically localized prostate cancer underwent interstitial permanent prostate brachytherapy using (125)I seeds. Median follow-up was 36 months (range, 30-42 months). Median initial prostate-specific antigen (PSA) level was 6.7 ng/ml (range, 1.5-25.2 ng/ml). Of these 100 patients, 31 received neoadjuvant hormone therapy for several months. Treatment morbidities were assessed using Radiation Therapy Oncology Group (RTOG) scale and National Cancer Institute Common Toxicity Criteria. RESULTS: A mean of 95 seeds (range, 48-123 seeds) were successfully implanted in patients with prostate cancer. Mean prostate volume receiving at least 100% dose (V100) and dose to 90% of prostate volume (D90) for the 100 patients were 96.6% and 166.1 Gy, respectively. Urinary morbidity was common, but was usually not severe. Only four patients needed catheterization for urinary retention (Grade 3) during follow-up. Most patients displayed no rectal morbidity after implantation, with only 3% of patients showing RTOG Grade 2 rectal morbidity and no patients showing morbidity of Grade 3 or more. Three patients experienced biochemical failure according to Phoenix consensus definition during follow-up. One patient displayed clinical failure with lymph node recurrence. CONCLUSIONS: These results indicate that interstitial permanent brachytherapy is safe and effective for Japanese patients with localized prostate cancer. The import of matured techniques developed in Western countries might allow bypass of the trial-and-error process in Japanese institutions.

Difference in rectal dosimetry between pre-plan and post-implant analysis in transperineal interstitial brachytherapy for prostate cancer.

BACKGROUND AND PURPOSE: To investigate differences in rectal dosimetry between pre-plan ultrasonography (US) and post-implant computed tomography (CT). PATIENTS AND METHODS: Subjects comprised 49 patients who underwent prostate brachytherapy using (125)I seed implants. Prescribed dose was 145Gy to the periphery of the prostate. Differences in rectal dosimetry between pre-plan US and post-implant CT analysis were evaluated. In addition, patients were divided into two groups according to timing of pre-planning (pre-plan group, n=28; intraoperative pre-plan group, n=21), and differences in rectal dosimetry between groups were assessed. RESULTS: The average of volume differences between pre-plan and post-implant analysis (pre-plan minus post-implant analysis) for all patients were follows: -0.08 cm(3) in V60 (volume of rectal wall receiving 60% of prescribed dose); -0.05 cm(3) in V70; -0.16 cm(3) in V80; -0.38 cm(3) in V90; -0.40 cm(3) in V100; -0.32 cm(3) in V110; -0.22 cm(3) in V120; -0.15 cm(3) in V130; -0.10 cm(3) in V140; -0.07 cm(3) in V150; and -0.05 cm(3) in V160. Apparent differences between pre-plan US and post-implant CT in rectal dosimetry were small. However, considering the steep curve of the relationship between tolerable volume and dose, a large actual difference should be assumed. No advantage was identified for the intraoperative pre-plan group. Safe volume to avoid proctitis tended to be smaller on ultrasonography than on CT at 1 month. CONCLUSIONS: The present work shows that direct comparison of CT analysis and pre-plan US is unfavorable due to large differences in these modalities and overestimation of tolerable volume. However, by comprehending the degree of difference, comparison of data from CT analysis with a US pre-plan may be feasible and useful for providing feedback between these modalities.

Simple technique to visualize random set-up displacements using a commercially available radiotherapy planning system.

PURPOSE: To visualize random set-up displacements in isodose distribution images, we introduce a simple technique using a commercially available radiotherapy planning system (RTP). MATERIALS AND METHODS: A distribution of set-up displacement is known to be compatible with that of a Gaussian distribution. Based on that assumption, 41 intentionally misaligned beams with 1-mm intervals were planned in the respective weights according to Gaussian distribution. "Modified" isodose distributions were then visualized using a commercially available RTP. In the next step, only two beams misaligned with one standard deviation (SD) of the Gaussian distribution were used in place of 41 beams, as a large number of beams increases the workload and is unsuitable for clinical use. Differences between the two versions of isodose distribution images were assessed visually. RESULTS: In modified dose distribution images, the edge of distribution was dull compared to normal images. These images show that the larger SD of set-up displacement dulls the edge of dose distribution. Images from two beams were not significantly different to those from 41 beams. CONCLUSION: Using this technique, the impact of random set-up displacements was effectively reflected in isodose distribution images.