Rectal and bladder motion during conformal radiotherapy after radical prostatectomy.

Background And Purpose: To investigate the extent and the impact of rectum and bladder motion during adjuvant conformal radiotherapy (3DCRT) after radical prostatectomy (RP).

Materials And Methods: Nine patients previously operated with RP and treated with early adjuvant 3DCRT were considered for this investigation. Weekly CT scans were collected during treatment (CT1-CTn, n=4-6) and were 3D matched using bony anatomy with the planning CT (CT0).

Fitting late rectal bleeding data using different NTCP models: results from an Italian multi-centric study (AIROPROS0101).

Background And Purpose: Recent investigations demonstrated a significant correlation between rectal dose-volume patterns and late rectal toxicity. The reduction of the DVH to a value expressing the probability of complication would be suitable. To fit different normal tissue complication probability (NTCP) models to clinical outcome on late rectal bleeding after external beam radiotherapy (RT) for prostate cancer.

Anatomic variations due to radical prostatectomy. Impact on target volume definition and dose-volume parameters of rectum and bladder.

Background And Purpose: A quantitative estimate of the impact of prostatectomy on pelvic anatomy is unavailable, even if it would be an important prerequisite for a precise definition of clinical target volume (CTV) in post-prostatectomy radiotherapy. The purpose of this study was to investigate the impact of prostatectomy on the definition of CTV, on the position of bladder and rectum and their implications for three-dimensional conformal radiotherapy (3-D CRT).

Patients And Methods: Six patients eligible for radical retropubic prostatectomy were considered.

Role of postoperative radiotherapy after pelvic lymphadenectomy and radical retropubic prostatectomy: a single institute experience of 415 patients.

Purpose: To evaluate the clinical benefit deriving from early (within 6 months) radiotherapy (ERT) after pelvic lymphadenectomy and radical retropubic prostatectomy for localized/locally advanced adenocarcinoma of the prostate in a single-institution series.

Methods And Materials: We retrospectively analyzed 415 patients who underwent pelvic lymphadenectomy and radical retropubic prostatectomy between 1986 and 1998 for pT2b-pT4, pN0-pN1 prostate carcinoma. Of the 415 patients, 237 underwent ERT for adverse pathologic findings and 178 patients did not receive RT or underwent salvage RT < or =6 months (salvage or no RT [SNRT]).

Rectal dose-volume constraints in high-dose radiotherapy of localized prostate cancer.

Purpose: To investigate the relationship between rectal bleeding and dosimetric-clinical parameters in patients receiving three-dimensional conformal radiotherapy (3D-CRT) for localized prostate cancer.

Methods: In a retrospective national study (AIROPROS01-01, AIRO: Associazione Italiana Radioterapia Oncologica), planning/clinical data for 245 consecutive patients with stage T1-4N0-x prostate carcinoma who underwent 3D-CRT to 70-78 Gy (ICRU point) were pooled from four Italian institutions. The correlation between late rectal bleeding and rectal dose-volume data (the percentage of rectum receiving more than 50, 55, 60, 65, 70, and 75 Gy [V(50-70)]) and other dosimetric and clinical parameters were investigated in univariate (log-rank) and multivariate (Cox regression model) analyses.

A cylindrical model of the rectum: comparing dose-volume, dose-surface and dose-wall histograms in the radiotherapy of prostate cancer.

The calculation of the percentage cumulative histogram of the rectal wall (DWH) in prostate cancer radiotherapy may be subject to large uncertainties due to the difficulty of assessing the wall thickness on CT images. For this reason often only the external contour is used to define the rectum and then the percentage cumulative dose-volume histogram (DVH) of the rectum including any filling is calculated as a 'surrogate' for the DWH. More recently, other approaches using only the external contour have been proposed to estimate the DWH such as the percentage normalized dose-surface histograms (NDSH).

The impact of contouring uncertainty on rectal 3D dose-volume data: results of a dummy run in a multicenter trial (AIROPROS01-02).

Purpose: To estimate the impact of the uncertainty in contouring the rectum on rectal dose-volume parameters and normal tissue complication probability (NTCP) in a prospective (AIROPROS01-02) investigation about rectal toxicity.

Methods And Materials: The participants in a prospective trial (18 observers) were asked to draw the external contour of the rectum of 4 sample patients (3 patients undergoing radical conformal radiotherapy, 1 patient undergoing post-prostatectomy) on CT images (0.5 cm spacing) using a 3D treatment planning system.

Inverse and forward optimization of one- and two-dimensional intensity-modulated radiation therapy-based treatment of concave-shaped planning target volumes: the case of prostate cancer.

Background: Intensity-modulated radiation therapy (IMRT) was suggested as a suitable technique to protect the rectal wall, while maintaining a satisfactory planning target volume (PTV) irradiation in the case of high-dose radiotherapy of prostate cancer. However, up to now, few investigations tried to estimate the expected benefit with respect to conventional three-dimensional (3D) conformal radiotherapy (CRT).

Purpose: Estimating the expected clinical gain coming from both 1D and 2D IMRT against 3DCRT, in the case of prostate cancer by mean of radiobiological models.

Significant correlation between rectal DVH and late bleeding in patients treated after radical prostatectomy with conformal or conventional radiotherapy (66.6-70.2 Gy).

Purpose: Investigating the correlation between dosimetric/clinical parameters and late rectal bleeding in patients treated with adjuvant or salvage radiotherapy after radical prostatectomy.

Methods And Materials: Data of 154 consecutive patients, including three-dimensional treatment planning and dose-volume histograms (DVHs) of the rectum (including filling), were retrospectively analyzed. Twenty-six of 154 patients presenting a (full) rectal volume >100 cc were excluded from the analysis.

In vivo estimation of midline dose maps by transit dosimetry in head and neck radiotherapy.

The aim of the present study is to compare the calculated midline dose map with the in vivo measured midline dose map, using portal detectors in conjunction with a pair of diodes. Measurements were performed in 10 patients treated for head/neck cancer and irradiated with lateral opposed 6 MV X-ray beams. The relative exit dose map, derived from transmission dose data of a portal film combined with the absolute entrance/exit dose measured by the diodes, can be used to derive the corresponding midline dose map by applying appropriate algorithms.

Relationships between DVHs and late rectal bleeding after radiotherapy for prostate cancer: analysis of a large group of patients pooled from three institutions.

Background: Accurate modeling of late rectal reactions needs the collection of individual 3D dose-volume data (i.e. DVH) as well as clinical information of large cohorts of patients.

Rectum contouring variability in patients treated for prostate cancer: impact on rectum dose-volume histograms and normal tissue complication probability.

Background: Recent investigations showed some correlation between three-dimensional (3D) treatment planning dose-volume data (dose-volume histograms: DVH, dose statistics) and rectal toxicity for patients treated for prostate cancer. However, no data are available about the possible impact of inter-institute variability in contouring the rectum, so that the possibility of reliably using information from single-centre studies remains doubtful.

Purpose: Within a retrospective three-institutes study on correlation between dose-volume treatment planning data and rectum bleeding in patients treated for prostate cancer, an investigation about the impact of inter- and intra-observer variability in contouring the rectum was performed.

Lethal pulmonary complications significantly correlate with individually assessed mean lung dose in patients with hematologic malignancies treated with total body irradiation.

Purpose: To assess the impact of lung dose on lethal pulmonary complications (LPCs) in a single-center group of patients with hematologic malignancies treated with total body irradiation (TBI) in the conditioning regimen for bone marrow transplantation (BMT).

Methods: The mean lung dose of 101 TBI-conditioned patients was assessed by a thorough (1 SD around 2%) in vivo transit dosimetry technique. Fractionated TBI (10 Gy, 3.

Irradiation fields and doses in glioblastoma multiforme: are current standards adequate?

Aims And Background: The optimum conventional radiotherapy in glioblastoma multiforme patients has not been clearly defined by prospective trials. To better characterize a standard radiotherapy in glioblastoma multiforme, the impact on survival of different fields and doses was analyzed in a retrospective single center series.

Methods: One hundred and forty-seven patients with glioblastoma multiforme, submitted to biopsy only (n = 15), subtotal (n = 48) or total resection (n = 82) and who completed the planned postsurgical radiotherapy, were considered.

Effect on local control and survival of electron beam intraoperative irradiation for resectable pancreatic adenocarcinoma.

Purpose: To assess the impact on local control and survival of intraoperative radiotherapy (IORT) in resectable pancreatic adenocarcinoma.

Methods And Materials: The outcome of 127 patients surgically treated with curative intent combined with IORT was compared with the therapeutic results of 76 patients treated with surgery as exclusive treatment.

Results: Operative mortality and morbidity were similar in IORT and no-IORT patients.

A simple and robust method for in vivo midline dose map estimations using diodes and portal detectors.

Introduction: This work investigates the possibility of using a pair of diodes on the beam axis in conjunction with a portal imaging detector to estimate in vivo midline dose distributions, without any additional patient information, related to the external body contour.

Materials And Methods: In the proposed method, the patient is considered equivalent to a parallelepiped phantom with a thickness z equal to the patient's physical thickness on the field axis with a variable electronic density rho, depending on the water-equivalent thickness. Based on this assumption, if the air gap between portal detector and patient is kept small (within 10-15 cm), the relative exit dose map may be assumed to be equal to the corresponding map measured at the portal detector level by geometrical back projection to the corresponding exit points.

Polarity effects of ionization chambers used in tbi dosimetry due to cable irradiation.

This paper presents the results of an investigation on polarity effects in total-body irradiation (TBI) dosimetry. Thimble (NE2571, 0.6 cc) and plane-parallel (Markus NE2534 0.

Quality assurance by systematic in vivo dosimetry: results on a large cohort of patients.

Background: In vivo dosimetry is widely considered to be an important tool for quality assurance in external radiotherapy.

Introduction: In this study we report on our experience over more than 4 years in systematic in vivo dosimetry with diodes.

Materials And Methods: From November '94 an in vivo entrance dosimetry check was performed for every new patient irradiated at one of our treatment units (Linac 6/100, 6 MV X-rays).

Conformal irradiation of concave-shaped PTVs in the treatment of prostate cancer by simple 1D intensity-modulated beams.

Background: In the case of concave-shaped PTVs including prostate (P) and seminal vesicles (SV), intensity-modulated radiation therapy (IMRT) should improve the therapeutic ratio of the treatment of prostate cancer.

Purpose: Comparing IMRT by simple 1D modulations with conventional 3D conformal therapy (i.e.

1D dynamic beam modulation: methods to counteract inertia effects.

Dynamic modulation can be affected by inaccuracies when the required acceleration is larger than the highest allowed by the mechanical characteristics of the whole apparatus. In this study, inertia effects have been investigated with regard to the single absorber 1D modulation, analysing primarily how the acceleration performed by the modulating system affects the realization of 'single absorber' fluence profiles and the type of correction which could be devised. The observed percentage deviations from desired modulation at the lowest fluence coordinate of single minimum fluence profiles, when no correction is applied, were almost negligible for 'easy' modulations of the incident fluence (i.

In-vivo dosimetry by diode semiconductors in combination with portal films during TBI: reporting a 5-year clinical experience.

Background And Purpose: In-vivo dosimetry is vital to assure an accurate delivery of total body irradiation (TBI). In-vivo lung dosimetry is strongly recommended because of the risk of radiation-induced interstitial pneumonia (IP). Here we report on our 5-year experience with in-vivo dosimetry using diodes in combination with portal films and assessing the effectiveness of in-vivo dosimetry in improving the accuracy of the treatment.

Use of dose-volume histograms and biophysical models to compare 2D and 3D irradiation techniques for non-small cell lung cancer.

For non-small cell lung cancer (NSCLC), unsatisfactory local control (LC) still remains an important cause of failure. It has been suggested that improved LC can be achieved with both higher radiation dosage and adequate target coverage. Modern three-dimensional treatment planning systems (3D-TPSs) offer many tools for planning optimization.

Dosimetry of Gamma Knife and linac-based radiosurgery using radiochromic and diode detectors.

In stereotactic radiosurgery the choice of appropriate detectors, whether for absolute or relative dosimetry, is very important due to the steep dose gradient and the incomplete lateral electronic equilibrium. For both linac-based and Leksell Gamma Knife radiosurgery units, we tested the use of calibrated radiochromic film to measure absolute doses and relative dose distributions. In addition a small diode was used to estimate the relative output factors.