Assessment of normal tissue complications following prostate cancer irradiation: Comparison of radiation treatment modalities using NTCP models (original) (raw)
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An NTCP Analysis of Urethral Complications from Low Doserate Mono- and Bi-Radionuclide Brachytherapy
Prostate cancer, 2011
Urethral NTCP has been determined for three prostates implanted with seeds based on (125)I (145 Gy), (103)Pd (125 Gy), (131)Cs (115 Gy), (103)Pd-(125)I (145 Gy), or (103)Pd-(131)Cs (115 Gy or 130 Gy). First, DU(20), meaning that 20% of the urhral volume receive a dose of at least DU(20), is converted into an I-125 LDR equivalent DU(20) in order to use the urethral NTCP model. Second, the propagation of uncertainties through the steps in the NTCP calculation was assessed in order to identify the parameters responsible for large data uncertainties. Two sets of radiobiological parameters were studied. The NTCP results all fall in the 19%-23% range and are associated with large uncertainties, making the comparison difficult. Depending on the dataset chosen, the ranking of NTCP values among the six seed implants studied changes. Moreover, the large uncertainties on the fitting parameters of the urethral NTCP model result in large uncertainty on the NTCP value. In conclusion, the use of N...
Dosimetric analysis of radiation therapy oncology group 0321: The importance of urethral dose
Practical Radiation Oncology, 2014
Purpose: Radiation Therapy Oncology Group 0321 is the first multi-institutional cooperative group high-dose-rate (HDR) prostate brachytherapy trial with complete digital brachytherapy dosimetry data. This is a descriptive report of the data and an analysis of toxicity. Methods and Materials: Patients are treated with external beam radiation therapy at 45 Gy and 1 HDR implant with 19 Gy in 2 fractions. Implants are done with transrectal ultrasound guidance, and computed tomography (CT)-compatible nonmetallic catheters. HDR planning is done on ≤ 3mm-thick CT slices. The "mean DVH" (dose-volume histogram) of the planning target volume (PTV), implanted volume (IP), and organs at risk are calculated. This includes the mean and standard deviation (SD) of the volume at 10-percentage-point intervals from 10% to 200% of the prescribed dose. The conformal index (COIN), homogeneity index (HI), catheters per implant, and patients per institution are calculated. Multivariate analysis and hazard ratios calculation of all the variables against reported grade ≥ 2 (G2 +) genitourinary (GU) adverse events (Common Terminology Criteria for Adverse Events, version 3) are performed. Results: Dosimetry data are based on 122 eligible patients from 14 institutions. The mean of PTV, IP, catheters per implant, and patients per institution are 54 cc, 63 cc, 19 and 9, respectively. The mean of %V100 PTV , V80 Bladder , V80 Rectum , and V120 Urethra were 94%, 0.40 cc, 0.15 cc, and 0.25 cc, respectively. There are too few G2 + gastrointestinal adverse event (GI AE) for correlative analysis; thus, the analysis has been performed on the more common G2 + GU AE. There are positive correlations noted between both acute and late G2 + GU AE and urethral dose at multiple levels. Positive correlations with late AE are seen with PTV and IP at high-dose levels. A negative Note-Earn CME credit by taking a brief online assessment at https://www.astro.org/JournalCME. Practical Radiation Oncology (2014) 4, 27-34 correlation is seen between HI and acute AE. A higher patient accrual rate is associated with a lower rate of G2 + acute and late AE. Conclusions: Higher urethral dose, larger high-dose volumes, and lower dose homogeneity are associated with greater toxicities. A mean dose-volume histogram comparison at all dose levels should be used for quality control and future research comparison.
International Journal of Radiation Oncology*Biology*Physics, 2014
Five rival treatment techniques for localized prostate cancer with excellent local control and moderate side effects were dosimetrically compared: intensitymodulated photon, proton, and carbon ion therapy, as well as low-dose-rate and high-dose-rate brachytherapy. All assumed total doses and fractionation schemes are clinically used. For comparison, dose distributions were radiobiologically converted to the same fractionation scheme. Brachytherapy techniques were Purpose: To assess the dosimetric differences among volumetric modulated arc therapy (VMAT), scanned proton therapy (intensity-modulated proton therapy, IMPT), scanned carbon-ion therapy (intensity-modulated carbon-ion therapy, IMIT), and low-dose-rate (LDR) and high-dose-rate (HDR) brachytherapy (BT) treatment of localized prostate cancer. Methods and Materials: Ten patients were considered for this planning study. For external beam radiation therapy (EBRT), planning target volume was created by adding a margin of 5 mm (lateral/anterioreposterior) and 8 mm (superioreinferior) to the clinical target volume. Bladder wall (BW), rectal wall (RW), femoral heads, urethra, and pelvic tissue were considered as organs at risk. For VMAT and IMPT, 78 Gy(relative biological effectiveness, RBE)/2 Gy were prescribed. The IMIT was based on 66 Gy(RBE)/20 fractions. The clinical target volume planning aims for HDR-BT (192 Ir) and LDR-BT (125 I) were D 90% !34 Gy in 8.5 Gy per fraction and D 90% !145 Gy. Both physical and RBE-weighted dose distributions for protons and carbon-ions were converted to dose distributions based on 2-Gy(IsoE) fractions. From these dose distributions various dose and doseevolume parameters were extracted. Results: Rectal wall exposure 30-70 Gy(IsoE) was reduced for IMIT, LDR-BT, and HDR-BT when compared with VMAT and IMPT. The high-dose region of the BW doseevolume histogram above 50 Gy(IsoE) of IMPT resembled the VMAT shape, whereas all other techniques showed a significantly lower high-dose region. For all 3 EBRT techniques similar urethra D mean around 74 Gy(IsoE) were obtained. The LDR-BT results were approximately 30 Gy(IsoE) higher, HDR-BT 10 Gy(IsoE) lower. Normal tissue and femoral head sparing was best with BT. Conclusion: Despite the different EBRT prescription and fractionation schemes, the high-dose regions of BW and RW expressed in Gy(IsoE) were on the same order of magnitude.
Long-term outcome of high dose rate brachytherapy in radiotherapy of localised prostate cancer
Radiotherapy and Oncology, 2005
Background and purpose: High dose rate brachytherapy (HDR-BT) in prostate cancer (PC) is receiving increasing interest. The steep dose gradient gives a possibility to escalate the dose to the prostate. If the a/b ratio is low for PC, hypofractionation will be of advantage. A retrospective analysis of outcome in patients (pts) consecutively treated with combined HDR-BT and conformal external beam radiotherapy (ERT) was performed. Material and methods: Data from 214 pts treated consecutively from 1988 to 2000 were analysed. The median age was 64 years (50-77). Median follow up was 4 years (12-165 months). Pre-irradiatory endocrine therapy was given to 150 pts (70%). The pts were divided into low-, intermediate-and high (80/87/47 pts) risk groups according to the occurrence of none, one, or more risk factors defined by T-classification, PSA and histopathology. ERT was given with 2 Gy fractions to 50 Gy. HDR-BT consisted of two 10 Gy fractions. Results: Overall 5-year biochemical no evidence of disease (bNED) was 82%, and for the low-, intermediate-, and high-risk group bNED was 92, 88 and 61%, respectively. PSA-relapse was found in 17, local recurrence in 3 and distant metastases in 13 pts. Five pts died of PC. No recurrences were observed after 5 years. Severe late complications were few. Urethral stricture (13 pts) was the most frequent. No severe rectal complications were seen. Conclusion: Dose escalation with HDR-BT is safe and effective in radiotherapy of localised PC.
International journal of radiation oncology, biology, physics, 2014
To identify an anatomic structure predictive for acute (AUT) and late (LUT) urinary toxicity in patients with prostate cancer treated with low-dose-rate brachytherapy (LDR) with or without external beam radiation therapy (EBRT). From July 2002 to January 2013, 927 patients with prostate cancer (median age, 66 years) underwent LDR brachytherapy with Iodine 125 (n=753) or Palladium 103 (n=174) as definitive treatment (n=478) and as a boost (n=449) followed by supplemental EBRT (median dose, 50.4 Gy). Structures contoured on the computed tomographic (CT) scan on day 0 after implantation included prostate, urethra, bladder, and the bladder neck, defined as 5 mm around the urethra between the catheter balloon and the prostatic urethra. AUT and LUT were assessed with the Common Terminology Criteria for Adverse Events, version4. Clinical and dosimetric factors associated with AUT and LUT were analyzed with Cox regression and receiver operating characteristic analysis to calculate area unde...
International Journal of Radiation Research, 2021
Background: Comparing three whole pelvic radiotherapy (WPRT) procedures as well as two local radiotherapy (LRT) procedures with each other for the treatment of prostate cancer patients using dosimetric parameters and radiobiological models: tumor control probability (TCP), normal tissue complication probability (NTCP), and equivalent uniform dose (EUD). Materials and Methods: Two groups of prostate cancer patients underwent WPRT (n=16) and LRT (n=16) procedures. In the WPRT group, the patients treated with two intensity modulated radiation therapy (IMRT+IMRT) procedures at two consecutive phases. Then, two other techniques including a three dimensional (3D) conformal radiation therapy (3DCRT) phase followed by an IMRT phase (3DCRT+IMRT) and also two consecutive 3DCRT procedures (3DCRT+3DCRT) were carried out on the patients' data. In the LRT group, the patients treated with just an IMRT technique. Then a 3DCRT technique was also performed on the patients' data. All the WPRT and LRT procedures compared with each other based on the dosimetric parameters and radiobiological models. Results: The mean of dosimetric parameters did not exceed the specified dose constraints for the bladder and femoral heads in the 3DCRT+ IMRT, and for the bladder in the 3DCRT technique. In the WPRT and LRT procedures, the TCP values for the prostate did not reveal any significant differences (P>0.05). The NTCP results in accordance with the dosimetric results for the organs at risk (OARs) showed a significant decrease in the IMRT+IMRT (WPRT) and the IMRT (LRT) techniques (P<0.05). However, the EUD results were dependent on the type of the procedure and OARs. Conclusion: For selecting the appropriate treatment technique for each prostate cancer patient, a compromise between the dosimetric and radiobiological evaluation of the WPRT and LRT procedures should be considered.
Medical Dosimetry, 2004
We report a methodology for comparing and combining dose information from external beam radiotherapy (EBRT) and interstitial brachytherapy (IB) components of prostate cancer treatment using the biological effective dose (BED). On a prototype early-stage prostate cancer patient treated with EBRT and low-dose rate I-125 brachytherapy, a 3-dimensional dose distribution was calculated for each of the EBRT and IB portions of treatment. For each component of treatment, the BED was calculated on a point-by-point basis to produce a BED distribution. These individual BED distributions could then be summed for combined therapies. BED dose-volume histograms (DVHs) of the prostate, urethra, rectum, and bladder were produced and compared for various combinations of EBRT and IB. Transformation to BED enabled computation of the relative contribution of each modality to the prostate dose, as the relative weighting of EBRT and IB was varied.
Journal of Radiotherapy in Practice, 2000
Ten patients with prostate cancer were each planned with 3 conventional and 3 conformal isocentric treatment techniques to compare the relative radiation doses to the bladder and rectal walls, and femoral head using dose volume histograms (DVH). The DVH were calculated for each organ and each technique, and the plans were ranked using the area under the curve method and also by the relative radiation dose given to specific normal tissue volumes.The results show that for the planning target volume chosen, the 4 field non-coplanar technique delivers the least dose to the bladder, the 6 field coplanar technique delivers the least dose to the rectum and the 3 field oblique technique delivers the least dose to the femoral heads. The 4-field technique with no shielding contributes the most dose to the bladder and rectum and the 6 field coplanar technique contributes the most dose to the femoral heads.No technique was shown to be optimal for all the organs at risk, but both the 6 field and...
Strahlentherapie und Onkologie, 2010
Purpose: To quantitatively evaluate the dose distributions of high-dose-rate (HDR) prostate implants regarding target coverage, dose homogeneity, and dose to organs at risk. Material and Methods: Treatment plans of 174 implants were evaluated using cumulative dose-volume histograms (DVHs). The planning was based on transrectal ultrasound (US) imaging, and the prescribed dose (100%) was 10 Gy. The tolerance doses to rectum and urethra were 80% and 120%, respectively. Dose-volume parameters for target (V90, V100, V150, V200, D90, D min ) and quality indices (DNR [dose nonuniformity ratio], DHI [dose homogeneity index], CI [coverage index], COIN [conformal index]) were calculated. Maximum dose in reference points of rectum (D r ) and urethra (D u ), dose to volume of 2 cm 3 of the rectum (D 2ccm ), and 0.1 cm 3 and 1% of the urethra (D 0.1ccm and D1) were determined. Nonparametric correlation analysis was performed between these parameters. Results: The median number of needles was 16, the mean prostate volume (V p ) was 27.1 cm 3 . The mean V90, V100, V150, and V200 were 99%, 97%, 39%, and 13%, respectively. The mean D90 was 109%, and the D min was 87%. The mean doses in rectum and urethra reference points were 75% and 119%, respectively. The mean volumetric doses were D 2ccm = 49% for the rectum, D 0.1ccm = 126%, and D1 = 140% for the urethra. The mean DNR was 0.37, while the DHI was 0.60. The mean COIN was 0.66. The Spearman rank order correlation coefficients for volume doses to rectum and urethra were R(D r ,D 2ccm ) = 0.69, R(D u ,D 0.1ccm ) = 0.64, R(D u ,D1) = 0.23. Conclusion: US-based treatment plans for HDR prostate implants based on the real positions of catheters provided acceptable dose distributions. In the majority of the cases, the doses to urethra and rectum were kept below the defined tolerance levels. For rectum, the dose in reference points correlated well with dose-volume parameters. For urethra dose characterization, the use of D1 volumetric parameter is recommended.