[en] Purpose: To compare dose distribution for two techniques of 3-dimensional conformal radiotherapy (RT): 6-field technique (6F) and 2-dynamic arc therapy (2DA). Methods and materials: Thirty nonmetastatic prostate cancer patients were included. In each patient, two treatment plans were prepared: with six coplanar fields (45 deg., 90 deg., 135 deg., 225 deg., 270 deg., 315 deg.) and with two dynamic lateral 100^o-wide arcs (40-140^o, 220-320^o). Dose-volume histograms (DVHs) were computed and mean area under curve (AUC) values were calculated for the DVHs of Planning Target Volume (PTV), rectum, urinary bladder and femoral heads. Doses given to 30% of rectum (DR₃), to 60% of rectum (DR₆), to 50% of bladder (DB₅), to 50% of femoral head (DF₅) and to 95% of PTV (DPTV₉₅) were reported as a percentage of the total dose. Results: Mean DR₃ and DR₆ for 6F and 2DA were 75.8%, 51.5% and 72.2%, 37.2%, respectively. Mean DB₅ for 6F and 2DA were 68% and 64.2%, respectively. Mean right DF₅ for 6F and 2DA were 35.4% and 45.5%, respectively. Mean DPTV₉₅ for 6F and 2DA were 99% and 99.2%, respectively. Mean AUCs of DVHs of rectum and urinary bladder were significantly higher for 6F (this was more evident for small PTV and in the intermediate dose range). Mean AUC of DVHs of PTV and femoral heads were significantly higher for 2DA. Conclusions: Both 6F and 2DA offer good dose distribution for PTV. 2DA allows for significantly better sparing of rectum and urinary bladder with slightly worse femoral head dose distribution. Further study is warranted in order to establish the clinical relevance of these differences

[en] Background and purpose: Limited information is available on the true radiation exposure and associated risks for the relatives of the patients submitted to prostate brachytherapy with permanent implant of radioactive sources and for any other people coming into contact with them. In order to provide appropriate information, we analyzed the radiation exposure data from 216 prostate cancer patients who underwent ¹²⁵I or ¹⁰³Pd implants at the European Institute of Oncology of Milan, Italy. Patients and methods: Between October 1999 and October 2004, 216 patients with low risk prostate carcinoma were treated with ¹²⁵I (200 patients) or ¹⁰³Pd (16 patients) permanent seed implantation. One day after the procedure, radiation exposure measurements around the patients were performed using an ionization chamber survey meter (Victoreen RPO-50) calibrated in dose rate at an accredited calibration center (calibration Centre SIT 104). Results: The mean dose rate at the posterior skin surface (gluteal region) following ¹²⁵I implants was 41.3 μSv/h (range: 6.2-99.4 μSv/h) and following ¹⁰³Pd implants was 18.9 μSv/h (range 5.0-37.3 μSv/h). The dose rate at 50 cm from the skin decreased to the mean value of 6.4 μSv/h for the ¹²⁵I implants and to the mean value of 1.7 μSv/h for the ¹⁰³Pd implants. Total times required to reach the annual dose limit (1 mSv/year) recommended for the general population by the European Directive 96/29/Euratom and by the Italian law (Decreto Legislativo 241/2000) at a distance of 50 cm from the posterior skin surface of the implanted patient would be 7.7 and 21.6 days for ¹²⁵I and for ¹⁰³Pd. Good correlation between the measured dose rates and both the total implanted activity and the distance between the most posteriorly implanted seed and the skin surface of the patients was found. Conclusions: Our data show that the dose rates at 50 cm away from the prostate brachytherapy patients are very low and that the doses possibly absorbed by the relatives and other members of the general population coming into contact with the treated patients are well below the dose limit set by the European Directive and by the Italian regulation. However, in order to meet the recommendation of the ALARA principle (As Low As Reasonably/Readily Achievable), some advice to the patients should be given, such as to maintain a minimum distance from the patient of 1 m, at least for a period equal to one half life of used radionuclide (60 days for ¹²⁵I and 15 days for ¹⁰³Pd)

[en] Purpose: To evaluate the outcome of postoperative radiotherapy (PORT) and salvage RT (SART) using a three-dimensional conformal two-dynamic arc (3D-ART) or 3D six-field technique in 431 prostate cancer patients. Methods and Materials: Of the 431 patients, 258 underwent PORT (started <6 months after radical prostatectomy) and 173 underwent SART because of biochemical failure after radical prostatectomy. The median patient age, preoperative prostate-specific antigen level, and Gleason score was 66 years, 9.4 ng/mL, and 7, respectively. The median radiation dose was 70 Gy in 35 fractions for both PORT and SART. The 3D six-field and 3D-ART techniques were used in 25.1% and 74.9% of patients, respectively. Biochemical failure was defined as a post-RT prostate-specific antigen nadir plus 0.1 ng/mL. Results: Acute toxicity included rectal events (PORT, 44.2% and 0.8% Grade 1-2 and Grade 3, respectively; SART, 42.2% and 1.2% Grade 1-2 and Grade 3, respectively) and urinary events (PORT, 51.2% and 2.3% Grade 1-2 and Grade 3-4, respectively; SART, 37.6% and 0% Grade 1-2 and Grade 3, respectively). Late toxicity also included rectal events (PORT, 14.7% and 0.8% Grade 1-2 and Grade 3-4, respectively; SART, 15.0% and 0.6% Grade 1-2 and Grade 3, respectively) and urinary events (PORT, 28.3% and 3.7% Grade 1-2 and Grade 3-4, respectively; SART, 19.3% and 0.6% Grade 1-2 and Grade 3, respectively). After a median follow-up of 48 months, failure-free survival, including biochemical and clinical failure, was significantly longer in the PORT patients (79.8% vs. 60.5%, p < 0.0001). Multivariate analysis showed that a prostate-specific antigen level postoperatively but before RT of ≥0.2 ng/mL (p < 0.001), Gleason score >6 (p = 0.025) and use of preoperative androgen deprivation (p = 0.002) correlated significantly with shorter failure-free survival. Multivariate analysis showed that PORT and the 3D-ART technique correlated with greater late urinary toxicity. Conclusion: PORT and early referral for SART offer better disease control after radical prostatectomy. The greater urinary toxicity occurring after PORT and 3D-ART requires further investigation to improve the therapeutic index.

[en] Purpose: In a previous paper we reported the results of off-line in vivo measurements using radiochromic films in IOERT. In the present study, a further step was made, aiming at the improvement of the effectiveness of in vivo dosimetry, based on a real-time check of the dose. Materials and methods: Entrance dose was determined using micro-MOSFET detectors placed inside a thin, sterile, transparent catheter. The epoxy side of the detector was faced towards the beam to minimize the anisotropy. Each detector was plugged into a bias supply (standard sensitivity) and calibrated at 5 Gy using 6 MeV electrons produced by a conventional linac. Detectors were characterized in terms of linearity, precision and dose per pulse dependence. No energy and temperature dependence was found. The sensitivity change of detectors was about 1% per 20 Gy accumulated dose. Correction factors to convert surface to entrance dose were determined for each combination of energy and applicator. From November 2004 to May 2005, in vivo dosimetry was performed on 45 patients affected by early-stage breast cancer, who underwent IOERT to the tumour bed. IOERT was delivered using electrons (4-10 MeV) at high dose per pulse, produced by either a Novac7 or a Liac mobile linac. Results: The mean ratio between measured and expected dose was 1.006±0.035 (1 SD), in the range 0.92-1.1. The procedure uncertainty was 3.6%. Micro-MOSFETs appeared suitable for in vivo dosimetry in IOERT, although some unfavourable aspects, like the limited lifetime and the anisotropy with no build-up, were found. Prospectively, a real-time action level (±6%) on dose discrepancy was defined. Conclusions: Excellent agreement between measured and expected doses was found. Real-time in vivo dosimetry appeared feasible, reliable and more effective than the method previously published

[en] Purpose: To present the results of dose escalation using three-dimensional conformal dynamic arc radiotherapy (3D-ART) for prostate cancer. Methods and Materials: Five hundred and forty two T1-T3N0M0 prostate cancer patients were treated with 3D-ART. Dose escalation (from 76 Gy/38 fractions to 80 Gy/40 fractions) was introduced in September 2003; 32% of patients received 80 Gy. In 366 patients, androgen deprivation was added to 3D-ART. Radiation Therapy Oncology Group/European Organization for Research and Treatment of Cancer criteria and Houston definition (nadir + 2) were used for toxicity and biochemical failure evaluation, respectively. Median follow-up was 25 months. Results: Acute toxicity included rectal (G1-2 28.9%; G3 0.5%) and urinary events (G1-2 57.9%; G3-4 2.4%). Late toxicity included rectal (G1-2 15.8%; G3-4 3.1%) and urinary events (G1-2 26.9%; G3-4 1.6%). Two-year failure-free survival and overall survival rates were 94.1% and 97.9%, respectively. Poor prognostic group (GS, iPSA, T), transurethral prostate resection, and dose >76 Gy showed significant association to high risk of progression in multivariate analysis (p = 0.014, p = 0.045, and p 0.04, respectively). The negative effect of dose >76 Gy was not observed (p 0.10), when the analysis was limited to 353 patients treated after September 2003 (when dose escalation was introduced). Higher dose was not associated with higher late toxicity. Conclusions: Three-dimensional-ART is a feasible modality allowing for dose escalation (no increase in toxicity has been observed with higher doses). However, the dose increase from 76 to 80 Gy was not associated with better tumor outcome. Further investigation is warranted for better understanding of the dose effect for prostate cancer

[en] Purpose: To compare the outcome of two different image-based postimplant dosimetry methods in permanent seed implantation. Methods and materials: Between October 1999 and October 2002, 150 patients with low-risk prostate carcinoma were treated with ¹²⁵I and ¹⁰³Pd in our institution. A CT-MRI image fusion protocol was used in 21 consecutive patients treated with exclusive brachytherapy. The accuracy and reproducibility of the method was calculated, and then the CT-based dosimetry was compared with the CT-MRI-based dosimetry using the dose-volume histogram (DVH) related parameters recommended by the American Brachytherapy Society and the American Association of Physicists in Medicine. Results: Our method for CT-MRI image fusion was accurate and reproducible (median shift <1 mm). Differences in prostate volume were found, depending on the image modality used. Quality assurance DVH-related parameters strongly depended on the image modality (CT vs. CT-MRI): V₁₀₀ = 82% vs. 88%, p < 0.05. D₉₀ = 96% vs. 115%, p < 0.05. Those results depend on the institutional implant technique and reflect the importance of lowering inter- and intraobserver discrepancies when outlining prostate and organs at risk for postimplant dosimetry. Conclusions: Computed tomography-MRI fused images allow accurate determination of prostate size, significantly improving the dosimetric evaluation based on DVH analysis. This provides a consistent method to judge a prostate seed implant's quality

[en] We report on 14 patients treated with linac- or robotic image-guided stereotactic radiotherapy for isolated lymph node recurrence from prostate cancer, up to the mean dose of 30 Gy/3 fractions. At the mean follow-up of 18.6 months, five patients experienced clinical out-field progression. Toxicity was minimal. Further investigation is warranted in order to identify the patients that benefit most from this treatment modality and to define the optimal association of such local approach with androgen deprivation. Hopefully, effective local therapy might reduce the burden of systemic therapies given to the recurrent/metastatic prostate cancer patients.

[en] Purpose: To evaluate the outcome of robotic CyberKnife (Accuray, Sunnyvale, CA)–based stereotactic radiotherapy (CBK-SRT) for isolated recurrent primary, lymph node, or metastatic prostate cancer. Methods and Materials: Between May 2007 and December 2009, 34 consecutive patients/38 lesions were treated (15 patients reirradiated for local recurrence [P], 4 patients reirradiated for anastomosis recurrence [A], 16 patients treated for single lymph node recurrence [LN], and 3 patients treated for single metastasis [M]). In all but 4 patients, [¹¹C]choline positron emission tomography/computed tomography was performed. CBK-SRT consisted of reirradiation and first radiotherapy in 27 and 11 lesions, respectively. The median CBK-SRT dose was 30 Gy in 4.5 fractions (P, 30 Gy in 5 fractions; A, 30 Gy in 5 fractions; LN, 33 Gy in 3 fractions; and M, 36 Gy in 3 fractions). In 18 patients (21 lesions) androgen deprivation was added to CBK-SRT (median duration, 16.6 months). Results: The median follow-up was 16.9 months. Acute toxicity included urinary events (3 Grade 1, 2 Grade 2, and 2 Grade 3 events) and rectal events (1 Grade 1 event). Late toxicity included urinary events (3 Grade 1, 2 Grade 2, and 2 Grade 3 events) and rectal events (1 Grade 1 event and 1 Grade 2 event). Biochemical response was observed in 32 of 38 evaluable lesions. Prostate-specific antigen stabilization was seen for 4 lesions, and in 2 cases prostate-specific antigen progression was reported. The 30-month progression-free survival rate was 42.6%. Disease progression was observed for 14 lesions (5, 2, 5, and 2 in Groups P, A, LN, and M respectively). In only 3 cases, in-field progression was seen. At the time of analysis (May 2010), 19 patients are alive with no evidence of disease and 15 are alive with disease. Conclusions: CyberKnife-based stereotactic radiotherapy is a feasible approach for isolated recurrent primary, lymph node, or metastatic prostate cancer, offering excellent in-field tumor control and a low toxicity profile. Further investigation is warranted to identify the patients who benefit most from this treatment modality. The optimal combination with androgen deprivation should also be defined.