[en] Objective: The use of escalated radiation doses to improve local control in conformal radiotherapy of prostatic cancer is becoming the focus of many centres. There are however increased side-effects associated with escalation radiotherapy doses which are believed to be dependent on the volume of normal tissue irradiated. For this reason, accurate patient positioning, CT planning with 3D reconstruction of volumes of interest, clear definition of treatment margins and verification of treatment fields are necessary components of the quality control for these procedures. In this study electronic portal images are used to i) evaluate the magnitude and effect of the setup errors encountered in our patient positioning techniques, and ii) verify the multileaf collimator (MLC) field patterns for each field on a daily basis. Methods and Materials: The Phase I volume, with a planning target volume (PTV) composed of the gross tumour volume (GTV) plus a 1.5cm margin is treated conformally with a 3-field plan (usually an anterior field and 2 post oblique fields). A Phase II, with no margin around the GTV, is treated using 2 lateral and 4 oblique fields. Portal images are acquired and compared to digitally reconstructed radiographs (DRR) and/or simulator films during Phase I in order to assess the systematic (simulator or planning to treatment error) and the daily random errors. The match results from these images are used to correct for the systematic errors, if necessary, and to monitor the time trends and effectiveness of patient immobilization systems used during the Phase I treatment course. For the Phase II, portal images of an anterior and lateral field (larger than the treatment fields) matched to DRR's (or simulator images) are used to verify the isocentre position on the first day of treatment. The Portal images are acquired for all the treatment fields on a daily basis to monitor the MLC field patterns. The final distribution of the setup errors are used to calculate modified dose volume histograms (DVH's). This procedure was carried out on 36 prostate cancer patients, 12 with vacuum moulded (VacFix) bags for immobilization and 24 with no immobilization. Results: The systematic errors can be visualised and corrected before the doses are increased above the conventional levels. The requirement for correction of these errors was demonstrated, using DVH's. A 2.5mm AP shift resulted in a 10% increase in rectal volume receiving at least 60Gy. The random (daily) errors observed showed the need for patient fixation devices in these setups with reduced margins. The percentage of fields with displacement of ≤5.0mm increased from 82% to 96% with the use of VacFix bags. The rotation of the pelvis is also minimised when the bags are used, with over 95% of the fields with rotations of ≤2.0⁰ compared to 85% without. Currently a combination of VacFix and thermoplastic casts is being investigated. Conclusion: The time trends observed during the course of Phase I in conjunction with the isocenter verification at the start of Phase II have been found to be adequate for setup verification during Phase II, where visibility of identifiable structures is reduced in the small fields. The acquisition and analysis of the portal images for these small fields has been found to be an effective way of checking MLC field patterns on daily basis. Incorporation of the distribution of the setup errors into the planning system, also gives a clearer picture of how the prescribed dose was delivered. This information can be useful in dose escalation studies in determining the relationship between the local control or morbidity rates and prescribed dose

[en] A multileaf collimator (MLC) can be used as a replacement for conventional blocks as well as for conformal radiotherapy. This study has assessed the possibility of using a Philips MLC for 218 patients treated with conventionally blocked fields. It was found that MLC field shaping would have been appropriate for over 94% of such patients. The facility to treat large blocked fields has been found to be particularly useful. Use of the predefined shapes stored in the Regular Shape Library provided by Philips was evaluated and it was found that an appropriate shape was available in 52% of cases. The application of MLC fields to the treatment of different anatomical sites is discussed

[en] A portal imaging system has been used, in conjunction with a movie measurement technique to measure set-up errors for 15 patients treated with radiotherapy of the pelvis and for 12 patients treated with radiotherapy of the brain. The pelvic patients were treated without fixation devices and the brain patients were treated with individually-moulded plastic shells. As would be expected the brain treatments were found to be more accurate than the pelvic treatments. Results are presented in terms of five error types: random error from treatment to treatment, error between mean treatment position and simulation position, random simulation error, systematic simulator-to-treatment errors and total treatment error. For the brain patients the simulation-to-treatment error predominates and random treatment errors were small (95% ≤ 3 mm, 77% ≤ 1.5 mm). Vector components of the systematic simulation-to-treatment errors were 1-2 mm with maximal random simulation error of ± 5 mm (2 S.D.). There is much interest in the number of verification films necessary to evaluate treatment accuracy. These results indicate that one check film performed at the first treatment is likely to be sufficient for set-up evaluation. For the pelvis the random treatment error is larger (95% ≤ 4.5 mm, 87% ≤ 3 mm). The systematic simulation-to-treatment error is up to 3 mm and the maximal random simulation error is ± 6 mm (2 S.D.). Thus corrections made solely on the basis of a first day check film may not be sufficient for adequate set-up evaluation

[en] Purpose: To evaluate the adequacy of tumor volume coverage using a three dimensional (3D) margin growing algorithm compared to a two dimensional (2D) margin growing algorithm in the conformal radiotherapy planning of prostate cancer. Methods and Materials: Two gross tumor volumes (GTV) were segmented in each of ten patients with localized prostate cancer: prostate gland only (PO) and prostate with seminal vesicles (PSV). A margin of 10 mm was applied to these two groups (PO and PSV) using both the 2D and 3D margin growing algorithms. The true planning target volume (PTV) was defined as the region delineated by the 3D algorithm. Adequacy of geometric coverage of the GTV with the two algorithms was examined throughout the target volume. Discrepancies between the two margin methods were measured in the transaxial plane. Results: The 2D algorithm underestimated the PTV by 17% (range 12-20) in the PO group and by 20% (range 13-28) for the PSV group when compared to the 3D algorithm. For both the PO and PSV groups, the inferior coverage of the PTV was consistently underestimated by the 2D margin algorithm when compared to the 3D margins with a mean radial distance of 4.8 mm (range 0-10). In the central region of the prostate gland, the anterior, posterior, and lateral PTV borders were underestimated with the 2D margin in both the PO and PSV groups by a mean of 3.6 mm (range 0-9), 2.1 mm (range 0-8), and 1.8 (range 0-9) respectively. The PTV coverage of the PO group superiorly was radially underestimated by 4.5mm (range 0-14) when comparing the 2D margins to the 3D margins. For the PSV group, the junction region between the prostate and the seminal vesicles was underestimated by the 2D margin by a mean transaxial distance of 18.1 mm in the anterior PTV border (range 4-30), 7.2 mm posteriorly (range 0-20), and 3.7 mm laterally (range 0-14). The superior region of the seminal vesicles in the PSV group was also consistently underestimated with a radial discrepancy of 3.3 mm (range 0-12). The maximum underestimation using the 2D algorithm occurred when the target volume angulated sharply to 90 deg. within successive adjacent slices resulting in transaxial plane differences of up to 20 and 55 mm respectively for the PO and PSV groups when compared to coverage by the 3D margin. This was most evident in the junction region of the PSV group. In this region, the 2D algorithm was inadequate, often not providing any margin (range 0-3 mm) in both the sagittal and coronal planes to the GTV compared to the 10 mm margin delineated with the 3D algorithm. Conclusion: This study illustrates the problem of assuming margins delineated in the transaxial plane are adequate to cover a 3D target volume. An appreciation of spatial margins in 3D is required if 2D margin growing algorithms are used. If 2D margin methods are utilised, beams eye view evaluations are required in sagittal and coronal planes to ensure adequate margin and coverage of the target volume

[en] The role of pelvic lymph node irradiation in the management of carcinoma of the prostate remains uncertain. However, in recent years, there has been an increasing appreciation that, in some patients, pelvic recurrence itself may be the source of subsequent distant metastases; also that increased local control should be the goal of therapy as it may in turn lead to improved quality of life and survival. This brief review examines the stires of pelvic lymph node metastases, their incidence and the prospects for treatment with radiotherapy. (author)

[en] Purpose: The use of escalated radiation doses to improve local control in conformal radiotherapy of prostatic cancer is becoming the focus of many centers. There are, however, increased side effects associated with increased radiotherapy doses that are believed to be dependent on the volume of normal tissue irradiated. For this reason, accurate patient positioning, CT planning with 3D reconstruction of volumes of interest, clear definition of treatment margins and verification of treatment fields are necessary components of the quality control for these procedures. In this study electronic portal images are used to (a) evaluate the magnitude and effect of the setup errors encountered in patient positioning techniques, and (b) verify the multileaf collimator (MLC) field patterns for each of the treatment fields. Methods and Materials: The Phase I volume, with a planning target volume (PTV) composed of the gross tumour volume (GTV) plus a 1.5 cm margin is treated conformally with a three-field plan (usually an anterior field and two lateral or oblique fields). A Phase II, with no margin around the GTV, is treated using two lateral and four oblique fields. Portal images are acquired and compared to digitally reconstructed radiographs (DRR) and/or simulator films during Phase I to assess the systematic (CT planning or simulator to treatment error) and the daily random errors. The match results from these images are used to correct for the systematic errors, if necessary, and to monitor the time trends and effectiveness of patient immobilization systems used during the Phase I treatment course. For the Phase II, portal images of an anterior and lateral field (larger than the treatment fields) matched to DRRs (or simulator images) are used to verify the isocenter position 1 week before start of Phase II. The Portal images are acquired for all the treatment fields on the first day to verify the MLC field patterns and archived for records. The final distribution of the setup errors was used to calculate modified dose-volume histograms (DVHs). This procedure was carried out on 36 prostate cancer patients, 12 with vacuum-molded (VacFix) bags for immobilization and 24 with no immobilization. Results: The systematic errors can be visualized and corrected for before the doses are increased above the conventional levels. The requirement for correction of these errors (e.g., 2.5 mm AP shift) was demonstrated, using DVHs, in the observed 10% increase in rectal volume receiving at least 60 Gy. The random (daily) errors observed showed the need for patient fixation devices when treating with reduced margins. The percentage of fields with displacements of ≤5.0 mm increased from 82 to 96% with the use of VacFix bags. The rotation of the pelvis is also minimized when the bags are used, with over 95% of the fields with rotations of ≤2.0 deg. compared to 85% without. Currently, a combination of VacFix and thermoplastic casts is being investigated. Conclusion: The systematic errors can easily be identified and corrected for in the early stages of the Phase I treatment course. The time trends observed during the course of Phase I in conjunction with the isocenter verification at the start of Phase II give good prediction of the accuracy of the setup during Phase II, where visibility of identifiable structures is reduced in the small fields. The acquisition and inspection of the portal images for the small Phase II fields has been found to be an effective way of keeping a record of the MLC field patterns used. Incorporation of the distribution of the setup errors into the planning system also gives a clearer picture of how the prescribed dose was delivered. This information can be useful in dose-escalation studies in determining the relationship between the local control or morbidity rates and prescribed dose

[en] A group of 149 patients with carcinoma of the tongue or floor of mouth were treated with interstitial irradiation (+- external beam therapy) using cesium needles or iridium wires between 1970 and 1986. Multivariate analysis showed the main predictors of outcome to be tumor stage, site and histology. Cesium and iridium techniques gave similarly good local control rates of 90 percent at 5 years for T₁ and T₂ tumors when used as the standard departmental method. Local failure was shown to have a major impact on the risk of dying from disease and elective neck irradiation (ENI) conferred a favorable benefit on neck control and survival provided the primary site was controlled. Patients less than age 40 appeared to have an unfavourable prognosis. Radical irradiation including interstitial techniques gives excellent results in early oral cancer and is the treatment of choice for T₂ tumours. The authors recommend elective neck irradiation in patients at high risk of developing lymph node metastases. (author). 32 refs.; 3 figs.; 6 tabs

[en] We report the effect on prostatic volume of the administration of the luteinising hormone-releasing hormone (LHRH) analogue goserelin in 22 patients with locally advanced carcinoma of the prostrate; 20 achieved a significant reduction in volume, the median volume being 66 ml before treatment and 30 ml after 17 weeks. If used before external beam radiotherapy (RT), volume reduction will permit smaller boost fields and thus potentially reduce adverse radiotherapy effects. In addition, reducing tumour volume before RT may lead to an increase in local control. We discuss the possible role of hormonal volume reduction in the management of prostatic cancer. (Author)

[en] The purpose of this pilot study was to evaluate the acute gastrointestinal morbidity of adjuvant radiotherapy (RT) for Stage I seminoma of the testis. Ten Stage I patients receiving para-aortic and ipsilateral pelvic nodal (dog-leg) RT provided a toxicity baseline (group A). Twenty Stage I patients randomized to dog-let RT or para-aortic RT (10 per group) were further randomized to received prophylactic ondansetron or expectant therapy with metoclopramide (group B). Daily patient-completed questionnaires evaluated acute toxicity. Dog-leg RT for Stage I seminomas is associated with readily demonstrable gastrointestinal tract (GIT) toxicity. The number of patients in this study is too small to produce definitive results, but there appears to be reduced GIT toxicity with prophylactic antiemetics. The effect of reduced RT fields has been assessed further in the MRC randomized tiral of field sizes (TE10). (Author)

[en] An asymptomatic rising serum prostate-specific antigen (PSA) level is the most common form of failure after radical radiotherapy for localized prostate cancer, but there is no consensus as to how it should be managed. This review addresses the following three questions concerning men with PSA failure after radiotherapy: (i) what is the course of the disease without further intervention?; (ii) what is the role of radical treatment, such as salvage prostatectomy?; and (iii) should androgen deprivation be started immediately or should it be delayed until clinical progression occurs? An algorithm for the management of PSA failure after radical radiotherapy for localized prostate cancer is proposed. (Copyright (c) 1998 Elsevier Science B.V., Amsterdam. All rights reserved.)