A randomized study of the use of a customized immobilization system in the treatment of prostate cancer with conformal radiotherapy

Patient and therapeutic radiographer experiences of comfort during the radiotherapy pathway: A qualitative study

INTRODUCTION

There is little research regarding the experiences of patient comfort and how it is best managed in radiotherapy. The aim of this study was to explore the experiences of patient and therapeutic radiographer views of comfort during radiotherapy.

METHODS

This qualitative study involved semi-structured interviews, with cancer patients (n = 25) and therapeutic radiographers (n = 25), conducted between January-July 2019. Patients were recruited from one radiotherapy clinic and therapeutic radiographers were recruited from across the United Kingdom via specialist interest groups and social media. Interviews were audio-recorded and transcribed verbatim. Thematic analysis was used to analyse the data separately between both groups and shared themes were identified.

RESULTS

Four themes were identified of which two themes were shared among both the patients and therapeutic radiographer. Emotional Health was a shared theme highlighting experiences such as stress, vulnerability and privacy. The second shared theme, Positioning and Immobilisation Experiences, concerned how patients' experience being physically positioned and using immobilisation for accurate radiotherapy. The theme Information and Communication Experience was derived from patients highlighting concerns over sharing and provision of information and ways of communication. The last theme, Environmental Experience, emerged from the patient interviews and related to the first impressions of the radiotherapy environment such as reception or treatment rooms and how this effects the overall feelings of comfort.

CONCLUSION

This qualitative study has provided the shared voice of patients and therapeutic radiographers and their experiences of comfort during radiotherapy. These shared experiences emphasise the importance of considering comfort holistically and not just from a physical context. This information can be used by therapeutic radiographers to better understand their patients experiences and needs to provide better comfort during radiotherapy to improve patients' outcomes.

IMPLICATIONS FOR PRACTICE

The clinical implications of our study can encourage Therapeutic Radiographers to provide holistic care for their patients throughout the pathway and specifically to comfort patients while they are having treatment. In the short term this could be via simple adaptions to practice while in the long term, research is needed to develop comfort interventions for patients receiving radiotherapy.

Comparing patient acceptability of MR-guided radiotherapy to conventional CBCT on two Elekta systems: a questionnaire-based survey

Background and Purpose:

The magnetic resonance linear accelerator system (MR Linac) is a novel piece of radiotherapy (RT) equipment allowing the routine application of daily MR-guided treatment adaptation. The hardware design required for such technical capabilities and the increased complexity of the treatment workflow entails a notable departure from cone beam computed tomography (CBCT)-based RT. Patient tolerability of treatment is paramount to RT practice where high compliance is required. Presented is a comparative analysis of how such modality specific characteristics may ultimately impact the patient experience of treatment.

Materials and Methods:

Forty patients undergoing RT for prostate cancer (PCa) on either the MR Linac (n = 20) or a CBCT-based linac (n = 20) were provided with a validated patient reported outcomes measures (PROM’s) questionnaire at fraction 1 and fraction 20. The 18-item questionnaire provided patient responses recorded using a 4-point Likert scale, 0 denoting a response of ‘Not at all’, 1 ‘Slightly’, 2 ‘Moderately’ and 3 signifying ‘Very’. The analysis provided insight into both comparisons between modalities at singular time points (fractions 1 and 20), as well as a temporal analysis within a single modality, denoting changing patient experience.

Results:

Patients generally found the MR Linac treatment couch more comfortable, however, found the increase in treatment duration harder to tolerate. Responses for all items remained stable between first and last fraction across both cohorts, indicating minimal temporal variation within a single modality. None of the responses were statistically significant at the 0·01 level.

Conclusion:

Whether radiotherapy for PCa is delivered on a CBCT linac or the MR Linac, there is little difference in patient experience with minimal experiential variation within a single modality.

Preliminary Clinical Evaluation of Intrafraction Prostate Displacements for Two Immobilization Systems

Immobilization systems and their corresponding set-up errors influence the clinical target volume to the planning target volume (CTV-PTV) margins, which is critical for hypofractionated prostate stereotactic body radiotherapy (SBRT). This preliminary study evaluates intrafraction prostate displacement for two immobilization systems (A and B). Six consecutive patients having localized prostate cancer and implanted prostate marker seeds were studied. Planar X-ray images were acquired pre- and post-treatment to find the intrafraction prostate displacement. The average absolute displacements (lateral, longitudinal, vertical) were 0.9 ± 0.4 mm, 1.7 ± 0.1 mm, 1.3 ± 0.3 mm (system A), and 0.5 ± 0.2 mm, 0.6 ± 0.1 mm, 0.8 ± 0.3 mm (system B), with average three-dimensional displacements of 2.6 ± 0.2 mm (system A) and 1.3 ± 0.2 mm (system B). The computed CTV-PTV margins (lateral, longitudinal, vertical) were 2.5 mm, 2.5 mm, 3.6 mm and 1.4 mm, 1.6 mm, 2.4 mm for systems A and B, respectively. This suggests that the immobilization system influences intrafraction prostate displacement and, therefore, the margins applied. However, the margins found for both systems are comparable to the margins used for hypofractionated prostate SBRT.

Ct Image Fusion as a Tool for Measuring in 3D the Setup Errors during Conformal Radiotherapy for Prostate Cancer

Aims and Background

The importance of optimal daily patient positioning has been stressed in order to ensure treatment reproducibility and gain in accuracy and precision. We report our data on the 3D setup uncertainty during radiation therapy for prostate cancer using the CT image fusion technique.

Methods

Ten consecutive patients scheduled for radiation therapy for prostate cancer underwent 5 prone position CT scans using an individualized immobilization cast. These different setups were analyzed using the image fusion module of the ERGO 3D-Line Medical System (Milan, Italy) treatment planning system. The isocenter and the body marker displacements were measured.

Results

The 3D isocenter dislocations were quantified: systematic error was Σ3D = 3.9 mm, whereas random error was σ3D = 1 mm. The mean of the minimum displacements was 0.2 ± 1 mm showing that the immobilization device used allows an accurate setup to be obtained. Single direction errors were also measured showing systematic errors, ΣAP = 2.6 mm, ΣLL = 0.6 mm, ΣSI = 3 mm in the anterior-posterior, latero-lateral, superior-inferior direction, respectively. Related random errors were σAP = 1 mm, σLL = 0.6 mm, σSI = 1.2 mm. In terms of accuracy, our uncertainties are similar to those reported in the literature.

Conclusions

By applying the CT image fusion technique, a 3D study on setup accuracy was performed. We demonstrated that the use of an individualized immobilization system for prostate treatment is adequate to obtain good setup accuracy, as long as a high-quality positioning control method, such as the stereoscopic X-ray-based positioning system, is used.

Immobilization versus no immobilization for pelvic external beam radiotherapy

Aim

To identify the most reproducible technique of patient positioning and immobilization during pelvic radiotherapy.

Background

Radiotherapy plays an important role in the treatment of pelvic malignancies. Errors in positioning of patient are an integral component of treatment. The present study compares two methods of immobilization with no immobilization with an aim of identifying the most reproducible method.

Materials and methods

65 consecutive patients receiving pelvic external beam radiotherapy were retrospectively analyzed. 30, 21 and 14 patients were treated with no-immobilization with a leg separator, whole body vacuum bag cushion (VBC) and six point aquaplast immobilization system, respectively. The systematic error, random error and the planning target volume (PTV) margins were calculated for all the three techniques and statistically analyzed.

Results

The systematic errors were the highest in the VBC and random errors were the highest in the aquaplast group. Both systematic and random errors were the lowest in patients treated with no-immobilization. 3D Systematic error (mm, mean ± 1SD) was 4.31 ± 3.84, 3.39 ± 1.71 and 2.42 ± 0.97 for VBC, aquaplast and no-immobilization, respectively. 3D random error (mm, 1SD) was 2.96, 3.59 and 1.39 for VBC, aquaplast and no-immobilization, respectively. The differences were statistically significant between all the three groups. The calculated PTV margins were the smallest for the no-immobilization technique with 4.56, 4.69 and 4.59 mm, respectively, in x, y and z axes, respectively.

Conclusions

Among the three techniques, no-immobilization technique with leg separator was the most reproducible technique with the smallest PTV margins. For obvious reasons, this technique is the least time consuming and most economically viable in developing countries.

The UK HeartSpare Study (Stage II): Multicentre Evaluation of a Voluntary Breath-hold Technique in Patients Receiving Breast Radiotherapy

AIMS

To evaluate the feasibility and heart-sparing ability of the voluntary breath-hold (VBH) technique in a multicentre setting.

MATERIALS AND METHODS

Patients were recruited from 10 UK centres. Following surgery for early left breast cancer, patients with any heart inside the 50% isodose from a standard free-breathing tangential field treatment plan underwent a second planning computed tomography (CT) scan using the VBH technique. A separate treatment plan was prepared on the VBH CT scan and used for treatment. The mean heart, left anterior descending coronary artery (LAD) and lung doses were calculated. Daily electronic portal imaging (EPI) was carried out and scanning/treatment times were recorded. The primary end point was the percentage of patients achieving a reduction in mean heart dose with VBH. Population systematic (Σ) and random errors (σ) were estimated. Within-patient comparisons between techniques used Wilcoxon signed-rank tests.

RESULTS

In total, 101 patients were recruited during 2014. Primary end point data were available for 93 patients, 88 (95%) of whom achieved a reduction in mean heart dose with VBH. Mean cardiac doses (Gy) for free-breathing and VBH techniques, respectively, were: heart 1.8 and 1.1, LAD 12.1 and 5.4, maximum LAD 35.4 and 24.1 (all P<0.001). Population EPI-based displacement data showed Σ =+1.3-1.9 mm and σ=1.4-1.8 mm. Median CT and treatment session times were 21 and 22 min, respectively.

CONCLUSIONS

The VBH technique is confirmed as effective in sparing heart tissue and is feasible in a multicentre setting.

A comparison of interfraction setup error, patient comfort, and therapist acceptance for 2 different prostate radiation therapy immobilization devices

PURPOSE

Our purpose was to investigate interfraction setup error of the immobilization device required to implement transperineal ultrasound compared with the current, standard immobilization device. Patient comfort and radiation therapist (RT) satisfaction were also assessed.

METHODS AND MATERIALS

Cone beam computed tomography images were acquired before 4069 fractions from 111 patients (control group, n = 56; intervention group, n = 55) were analyzed. The intervention group was immobilized using the Clarity Immobilization System (CIS), comprising a knee rest with autoscan probe kit and transperineal ultrasound probe (n = 55), and control group using a leg immobilizer (LI) (n = 56). Interfraction setup errors were compared for both groups. Weekly questionnaires using a 10-point visual analog scale were administered to both patient groups to measure and compare patient comfort. RT acceptance for both devices was also compared using a survey.

RESULTS

There was no significant difference in the magnitude of interfraction cone beam computed tomography-derived setup shifts in the lateral and anteroposterior direction between the LI and CIS (P = .878 and .690, respectively). However, a significant difference (P = .003) was observed in the superoinferior direction between the 2 groups of patients. Patient-reported level of comfort and stability demonstrated no significant difference between groups (P = .994 and .132). RT user acceptance measures for the LI and CIS were ease of handling (100% vs 53.7%), storage (100% vs 61.1%), and cleaning of the devices (100% vs 64.8%), respectively.

CONCLUSIONS

The CIS demonstrated stability and reproducibility in prostate treatment setup comparable to LI. The CIS device had no impact on patient comfort; however, RTs indicated a preference for LI over the CIS mainly because of its weight and bulkiness.

A focus group consultation round exploring patient experiences of comfort during radiotherapy for head and neck cancer

Purpose

The aim of this study was to consult patients about their experiences of comfort while wearing a thermoplastic mask during head and neck radiotherapy before designing a study to develop a comfort scale for radiotherapy.

Methods

A qualitative method using a focus group of patients receiving radiotherapy for head and neck cancer was deployed. Five patients were invited and agreed to participate. Semi-structured questions guided the focus group interview. Thematic analysis was used to identify themes.

Findings

Three patients participated in the focus group. Three main themes were identified: Physical comfort, Mental perception, Passivity. Physical comfort derived from feelings of pressure, unpleasantness, and generally being uncomfortable. Mental perception derived from how the physical comfort was perceived and derived from feelings of shock, anxiety, indifference and sensory systems. Passivity arose from feelings such as the ‘doctor knows best’, ‘putting up with it’, and ‘being taken for a ride’.

Conclusion

The insight of patient’s comfort and experiences are valuable for clinicians to provide patient-centred care. Findings of this study implicate further investigation of how the themes of patient comfort can be measured in radiotherapy to improve the patient experience.

Setup error analysis in helical tomotherapy based image-guided radiation therapy treatments

The adequacy of setup margins for various sites in patients treated with helical tomotherapy was investigated. A total of 102 patients were investigated. The breakdown of the patients were as follows: Twenty-five patients each in brain, head and neck (H and N), and pelvis, while 12 patients in lung and 15 in craniospinal irradiation (CSI). Patients were immobilized on the institutional protocol. Altogether 2686 megavoltage computed tomography images were analyzed with 672, 747, 622, 333, and 312 fractions, respectively, from brain, H and N, pelvis, lung, and CSI. Overall systematic and random errors were calculated in three translational and three rotational directions. Setup margins were evaluated using van Herk formula. The calculated margins were compared with the margins in the clinical use for various directions and sites. We found that the clinical isotropic margin of 3 mm was adequate for brain patients. However, in the longitudinal direction it was found to be out of margin by 0.7 mm. In H and N, the calculated margins were well within the isotropic margin of 5 mm which is in clinical use. In pelvis, the calculated margin was within the limits, 8.3 mm versus 10 mm only in longitudinal direction, however, in vertical and lateral directions the calculated margins were out of clinical margins 11 mm versus 10 mm, and 8.7 mm versus 7.0, mm respectively. In lung, all the calculated margins were well within the margins used clinically. In CSI, the variation was found in the middle spine in the longitudinal direction. The clinical margins used in our hospital are adequate enough for sites H and N, lung, and brain, however, for CSI and pelvis the margins were found to be out of clinical margins.

The UK HeartSpare Study (Stage IB): randomised comparison of a voluntary breath-hold technique and prone radiotherapy after breast conserving surgery

PURPOSE

To compare mean heart and left anterior descending coronary artery (LAD) doses (NTDmean) and positional reproducibility in larger-breasted women receiving left breast radiotherapy using supine voluntary deep-inspiratory breath-hold (VBH) and free-breathing prone techniques.

MATERIALS AND METHODS

Following surgery for early breast cancer, patients with estimated breast volumes >750 cm(3) underwent planning-CT scans in supine VBH and free-breathing prone positions. Radiotherapy treatment plans were prepared, and mean heart and LAD doses were calculated. Patients were randomised to receive one technique for fractions 1-7, before switching techniques for fractions 8-15 (40 Gy/15 fractions total). Daily electronic portal imaging and alternate-day cone-beam CT (CBCT) imaging were performed. The primary endpoint was the difference in mean LAD NTDmean between techniques. Population systematic (Σ) and random errors (σ) were estimated. Within-patient comparisons between techniques used Wilcoxon signed-rank tests.

RESULTS

34 patients were recruited, with complete dosimetric data available for 28. Mean heart and LAD NTDmean doses for VBH and prone treatments respectively were 0.4 and 0.7 (p<0.001) and 2.9 and 7.8 (p<0.001). Clip-based CBCT errors for VBH and prone respectively were ⩽3.0 mm and ⩽6.5 mm (Σ) and ⩽3.5 mm and ⩽5.4 mm (σ).

CONCLUSIONS

In larger-breasted women, supine VBH provided superior cardiac sparing and reproducibility than a free-breathing prone position.

Voluntary breath-hold technique for reducing heart dose in left breast radiotherapy

Breath-holding techniques reduce the amount of radiation received by cardiac structures during tangential-field left breast radiotherapy. With these techniques, patients hold their breath while radiotherapy is delivered, pushing the heart down and away from the radiotherapy field. Despite clear dosimetric benefits, these techniques are not yet in widespread use. One reason for this is that commercially available solutions require specialist equipment, necessitating not only significant capital investment, but often also incurring ongoing costs such as a need for daily disposable mouthpieces. The voluntary breath-hold technique described here does not require any additional specialist equipment. All breath-holding techniques require a surrogate to monitor breath-hold consistency and whether breath-hold is maintained. Voluntary breath-hold uses the distance moved by the anterior and lateral reference marks (tattoos) away from the treatment room lasers in breath-hold to monitor consistency at CT-planning and treatment setup. Light fields are then used to monitor breath-hold consistency prior to and during radiotherapy delivery.

A comparison of two systems of patient immobilization for prostate radiotherapy

BACKGROUND

Reproducibility of different immobilization systems, which may affect set-up errors, remains uncertain. Immobilization systems and their corresponding set-up errors influence the clinical target volume to planning target volume (CTV-PTV) margins and thus may result in undesirable treatment outcomes. This study compared the reproducibility of patient positioning with Hipfix system and whole body alpha cradle with respect to localized prostate cancer and investigated the existing CTV-PTV margins in the clinical oncology departments of two hospitals.

METHODS

Forty sets of data of patients with localized T1-T3 prostate cancer were randomly selected from two regional hospitals, with 20 patients immobilized by a whole-body alpha cradle system and 20 by a thermoplastic Hipfix system. Seven sets of the anterior-posterior (AP), cranial-caudal (CC) and medial-lateral (ML) deviations were collected from each patient. The reproducibility of patient positioning within the two hospitals was compared using a total vector error (TVE) parameter. In addition, CTV-PTV margins were computed using van Herk's formula. The resulting values were compared to the current CTV-PTV margins in both hospitals.

RESULTS

The TVE values were 5.1 and 2.8 mm for the Hipfix and the whole-body alpha cradle systems respectively. TVE associated with the whole-body alpha cradle system was found to be significantly less than the Hipfix system (p < 0.05). The CC axis in the Hipfix system attained the highest frequency of large (23.6%) and serious (7.9%) set-up errors. The calculated CTV to PTV margin was 8.3, 1.9 and 2.3 mm for the Hipfix system, and 2.1, 3.4 and 1.8 mm for the whole body alpha cradle in CC, ML and AP axes respectively. All but one (CC axis using Hipfix) margin calculated did not exceed the corresponding hospital protocol. The whole body alpha cradle system was found to be significantly better than the Hipfix system in terms of reproducibility (p < 0.05), especially in the CC axis.

CONCLUSIONS

The whole body alpha cradle system was more reproducible than the Hipfix system. In particular, the difference in CC axis contributed most to the results and the current CC margin for the Hipfix system might be considered as inadequate.

Set-up accuracy of an external immobilisation system for patients receiving radical radiotherapy for prostate cancer

Purpose: To evaluate the accuracy of an external immobilisation system in patients receiving radiotherapy for prostate cancer.

Methods: Portal Imaging data were audited in 20 patients treated using an in-house immobilisation system and 20 patients treated using an indexed commercial immobilisation system (Combifix™). Individual and group random and systematic errors were calculated to determine the accuracy of set-up using skin marks alone and with a no-action-level protocol.

Results: The initial results showed a larger systematic error in the Combifix™ in the anterior-posterior direction (2.7 mm) compared with the in-house system (1.5 mm). The possible source of this was identified as the difficulty in accurately aligning the laser to a curved couch top prior to setting the isocentre height. A change in the process of setting the isocentre was introduced, and comparable baseline set-up accuracy was achieved. This was with a systematic error of ≤2.0 mm and a random error ≤1.5 mm of patient position set-up error with skin marks alone, and using the Combifix™. The systematic errors were further reduced to <1 mm with an off-line no-action-level protocol.

Conclusion: Using the Combifix™ system a high level of set-up accuracy was reproduced in routine daily practice.

A Retrospective Review of the Effect of a Simple Foot Immobilization Device for the Treatment of Prostate Cancer

BACKGROUND

The goal of radical radiation therapy is to eradicate tumor cells by delivering maximum dose to the target volume. This requires accurate daily positioning of the patient to minimize the chances of a geographical miss of the target and minimize dose to surrounding normal tissue. Numerous studies have been conducted to find the best immobilization device to improve reproducibility and setup of patient positioning for men with prostate cancer with inconclusive results.

OBJECTIVE

The aim of this study was to evaluate retrospectively, the consistency and reproducibility of prostate patient positioning using a simple foot immobilization device compared with patients treated without any immobilization device.

METHODS

A retrospective chart analysis was completed on 40 patients with histopathologically confirmed adenocarcinoma of the prostate between April 2007 and May 2007. Twenty charts were randomly selected for men treated without any immobilization device and 20 charts were randomly selected for men treated with the foot strap immobilization. Incidence and frequency of isocenter shifts were the primary end points of this study. Direction and magnitude of shifts were secondary end points.

RESULTS

The frequency of isocenter shifts were greater in the patients treated without immobilization (35%) than with patients treated with foot strap immobilization (10%). Required shifts were in either the superoinferior direction or in the right/left direction. No shifts were required in the anteroposterior direction. Magnitude of shifts greater than and equal to 1.0 cm in magnitude was seen only in those treated without immobilization.

CONCLUSION

The foot strap is a simple and inexpensive method of improving daily setup reliability and reducing the need for isocenter shifts.

Setup reproducibility for thoracic and upper gastrointestinal radiation therapy: Influence of immobilization method and on-line cone-beam CT guidance

We report the setup reproducibility of thoracic and upper gastrointestinal (UGI) radiotherapy (RT) patients for 2 immobilization methods evaluated through cone-beam computed tomography (CBCT) image guidance, and present planning target volume (PTV) margin calculations made on the basis of these observations. Daily CBCT images from 65 patients immobilized in a chestboard (CB) or evacuated cushion (EC) were registered to the planning CT using automatic bony anatomy registration. The standardized region-of-interest for matching was focused around vertebral bodies adjacent to tumor location. Discrepancies >3 mm between the CBCT and CT datasets were corrected before initiation of RT and verified with a second CBCT to assess residual error (usually taken after 90 s of the initial CBCT). Positional data were analyzed to evaluate the magnitude and frequencies of setup errors before and after correction. The setup distributions were slightly different for the CB (797 scans) and EC (757 scans) methods, and the probability of adjustment at a 3-mm action threshold was not significantly different (p = 0.47). Setup displacements >10 mm in any direction were observed in 10% of CB fractions and 16% of EC fractions (p = 0.0008). Residual error distributions after CBCT guidance were equivalent regardless of immobilization method. Using a published formula, the PTV margins for the CB were L/R, 3.3 mm; S/I, 3.5 mm; and A/P, 4.6 mm), and for EC they were L/R, 3.7 mm; S/I, 3.3 mm; and A/P, 4.6 mm. In the absence of image guidance, the CB slightly outperformed the EC in precision. CBCT allows reduction to a single immobilization system that can be chosen for efficiency, logistics, and cost. Image guidance allows for increased geometric precision and accuracy and supports a corresponding reduction in PTV margin.

A randomized crossover study evaluating two immobilization devices for prostate cancer treatment

Purpose: To compare the Combifix® immobilization device with a conventional double-leg cushion in terms of patient comfort, therapist feedback and systematic/random error outcomes.

Materials and Methods: This prospective block-randomised crossover study enrolled 18 high-risk prostate cancer patients who received whole pelvic plus prostate radiotherapy. Treatment consisted of a prostate boost with one immobilization device followed by whole pelvic radiation using the other device. Our primary endpoints were device ease-of-use and patient comfort. Secondary endpoints included treatment time and systematic/random error assessments.

Results: While our patients found both devices equally comfortable and easy to use, the therapists preferred the leg cushion for ease of set-up (p = 0.04). Patient treatment time was similar for the two devices. In terms of electronic portal imaging (EPID)-based isocentre shifts, statistically, but not clinically, significant differences in systematic and random errors between the two devices exist in the superior–inferior directions (p ≤ 0.05).

Conclusions: No clinically important advantage was seen with the Combifix® device versus our standard double-leg cushion in terms of patient/therapist preference, patient comfort, and bony pelvic immobilization. However, this research project confirmed the feasibility of mounting a small single-institution randomised crossover technology assessment related to a practical radiotherapy issue.

Automatic registration of portal images and volumetric CT for patient positioning in radiation therapy

The efficacy of radiation therapy treatment depends on the patient setup accuracy at each daily fraction. A significant problem is reproducing the patient position during treatment planning for every fraction of the treatment process. We propose and evaluate an intensity based automatic registration method using multiple portal images and the pre-treatment CT volume. We perform both geometric and radiometric calibrations to generate high quality digitally reconstructed radiographs (DRRs) that can be compared against portal images acquired right before treatment dose delivery. We use a graphics processing unit (GPU) to generate the DRRs in order to gain computational efficiency. We also perform a comparative study on various similarity measures and optimization procedures. Simple similarity measure such as local normalized correlation (LNC) performs best as long as the radiometric calibration is carefully done. Using the proposed method, we achieved better than 1mm average error in repositioning accuracy for a series of phantom studies using two open field (i.e., 41 cm2) portal images with 90 degrees vergence angle.

Clinical use of electronic portal imaging

Accurate and routine target localization is necessary for successful outcome in radiation therapy treatments. Electronic portal imaging devices (EPIDs) provide an advanced tool with digital technology to improve target localization and maintain clinical efficiency. EPIDs are ubiquitous in the radiation therapy clinic, and they provide a powerful and flexible tool to collect and process data in a quantitative manner to improve treatment accuracy for virtually any treatment site. This manuscript provides an overview of the clinical implementation process for effective use of EPIDs. It continues with a review of correction strategies and finally highlights numerous examples of effective clinical application of EPID.

Phase III pilot study of dose escalation using conformal radiotherapy in prostate cancer: PSA control and side effects

Radical radiotherapy is a standard form of management of localised prostate cancer. Conformal treatment planning spares adjacent normal tissues reducing treatment-related side effects and may permit safe dose escalation. We have tested the effects on tumour control and side effects of escalating radiotherapy dose and investigated the appropriate target volume margin. After an initial 3-6 month period of androgen suppression, 126 men were randomised and treated with radiotherapy using a 2 by 2 factorial trial design. The initial radiotherapy tumour target volume included the prostate and base of seminal vesicles (SV) or complete SV depending on SV involvement risk. Treatments were randomised to deliver a dose of 64 Gy with either a 1.0 or 1.5 cm margin around the tumour volume (1.0 and 1.5 cm margin groups) and also to treat either with or without a 10 Gy boost to the prostate alone with no additional margin (64 and 74 Gy groups). Tumour control was monitored by prostate-specific antigen (PSA) testing and clinical examination with additional tests as appropriate. Acute and late side effects of treatment were measured using the Radiation Treatment and Oncology Groups (RTOG) and LENT SOM systems. The results showed that freedom from PSA failure was higher in the 74 Gy group compared to the 64 Gy group, but this did not reach conventional levels of statistical significance with 5-year actuarial control rates of 71% (95% CI 58-81%) in the 74 Gy group vs 59% (95% CI 45-70%) in the 64 Gy group. There were 23 failures in the 74 Gy group and 33 in the 64 Gy group (Hazard ratio 0.64, 95% CI 0.38-1.10, P=0.10). No difference in disease control was seen between the 1.0 and 1.5 cm margin groups (5-year actuarial control rates 67%, 95% CI 53-77% vs 63%, 95% CI 50-74%) with 28 events in each group (Hazard ratio 0.97, 95% CI 0.50-1.86, P=0.94). Acute side effects were generally mild and 18 weeks after treatment, only four and five of the 126 men had persistent > or =Grade 1 bowel or bladder side effects, respectively. Statistically significant increases in acute bladder side effects were seen after treatment in the men receiving 74 Gy (P=0.006), and increases in both acute bowel side effects during treatment (P=0.05) and acute bladder sequelae (P=0.002) were recorded for men in the 1.5 cm margin group. While statistically significant, these differences were of short duration and of doubtful clinical importance. Late bowel side effects (RTOG> or =2) were seen more commonly in the 74 Gy and 1.5 cm margin groups (P=0.02 and P=0.05, respectively) in the first 2 years after randomisation. Similar results were found using the LENT SOM assessments. No significant differences in late bladder side effects were seen between the randomised groups using the RTOG scoring system. Using the LENT SOM instrument, a higher proportion of men treated in the 74 Gy group had Grade > or =3 urinary frequency at 6 and 12 months. Compared to baseline scores, bladder symptoms improved after 6 months or more follow-up in all groups. Sexual function deteriorated after treatment with the number of men reporting some sexual dysfunction (Grade> or =1) increasing from 38% at baseline to 66% at 6 months and 1 year and 81% by year 5. However, no consistent differences were seen between the randomised groups. In conclusion, dose escalation from 64 to 74 Gy using conformal radiotherapy may improve long-term PSA control, but a treatment margin of 1.5 cm is unnecessary and is associated with increased acute bowel and bladder reactions and more late rectal side effects. Data from this randomised pilot study informed the Data Monitoring Committee of the Medical Research Council RT 01 Trial and the two studies will be combined in subsequent meta-analysis.

Impact of knee support and shape of tabletop on rectum and prostate position

PURPOSE

To evaluate the impact of different tabletops with or without a knee support on the position of the rectum, prostate, and bulb of the penis; and to evaluate the effect of these patient-positioning devices on treatment planning.

METHODS AND MATERIALS

For 10 male volunteers, five MRI scans were made in four different positions: on a flat tabletop with knee support, on a flat tabletop without knee support, on a rounded tabletop with knee support, and on a rounded tabletop without knee support. The fifth scan was in the same position as the first. With image registration, the position differences of the rectum, prostate, and bulb of the penis were measured at several points in a sagittal plane through the central axis of the prostate. A planning target volume was generated from the delineated prostates with a margin of 10 mm in three dimensions. A three-field treatment plan with a prescribed dose of 78 Gy to the International Commission on Radiation Units and Measurements point was automatically generated from each planning target volume. Dose-volume histograms were calculated for all rectal walls.

RESULTS

The shape of the tabletop did not affect the rectum and prostate position. Addition of a knee support shifted the anterior and posterior rectal walls dorsally. For the anterior rectal wall, the maximum dorsal shift was 9.9 mm (standard error of the mean [SEM] 1.7 mm) at the top of the prostate. For the posterior rectal wall, the maximum dorsal shift was 10.2 mm (SEM 1.5 mm) at the middle of the prostate. Therefore, the rectal filling was pushed caudally when a knee support was added. The knee support caused a rotation of the prostate around the left-right axis at the apex (i.e., a dorsal rotation) by 5.6 degrees (SEM 0.8 degrees ) and shifts in the caudal and dorsal directions of 2.6 mm (SEM 0.4 cm) and 1.4 mm (SEM 0.6 mm), respectively. The position of the bulb of the penis was not influenced by the use of a knee support or rounded tabletop. The volume of the rectal wall receiving the same dose range (e.g., 40-75 Gy) was reduced by 3.5% (SEM 0.9%) when a knee support was added. No significant differences were observed between the first and fifth scan (flat tabletop with knee support) for all measured points, thereby excluding time trends.

CONCLUSIONS

The rectum and prostate were significantly shifted dorsally by the use of a knee support. The rectum shifted more than the prostate, resulting in a dose benefit compared with irradiation without knee support. The shape of the tabletop did not influence the rectum or prostate position.

Questionnaire based quality assurance for the RT01 trial of dose escalation in conformal radiotherapy for prostate cancer (ISRCTN 47772397)

BACKGROUND AND PURPOSE

In order to ensure the validity of the outcome of the Medical Research Council's 'RTO1 trial' of dose escalation in conformal radiotherapy for prostate cancer it was considered important that the quality of treatment delivery should meet an adequate standard across all contributing centres. A questionnaire was therefore devised to ensure that all aspects of the planning and delivery process were adequately covered.

PATIENTS AND METHODS

The questionnaire considered each step in the planning and delivery process and drew the attention of the participants to the specific requirements of the trial. Before entering patients into the trial each participating centre had to complete the questionnaire and an outlining exercise (reported elsewhere).

RESULTS

It was not practicable to define a detailed universally acceptable protocol for the whole process of delivery of conformal radiotherapy, not least because of the different equipment available for planning and treatment in different centres. The questionnaire identified some areas of difference in practice between centres where there may be a need for the development of a consensus as to best practice, particularly in the area of patient set-up. Occasionally it was necessary to follow up responses to questions that had been misunderstood or inadequately answered, but in most cases these issues proved to be easily resolved.

CONCLUSIONS

The questionnaire proved to be a useful self-assessment tool as well as enabling the quality assurance group to ensure that the standards of the trial were being met. Subsequent follow-up visits confirmed the usefulness and validity of this self assessment process.

A randomized trial of supine vs. prone positioning in patients undergoing escalated dose conformal radiotherapy for prostate cancer

BACKGROUND AND PURPOSE

The optimal treatment position for patients receiving radical radiation therapy for prostate cancer has been a source of controversy. To resolve this issue, we conducted a randomized trial to evaluate the effects of supine and prone positioning on organ motion, positioning errors, and dose to critical organs during escalated dose conformal irradiation for localized prostate cancer and patient and therapist satisfaction with setup technique.

PATIENTS AND METHODS

Twenty eight patients were randomized to commence treatment immobilized in the supine or prone position and were subsequently changed to the alternate positioning for the latter half of their treatment. Patients underwent CT simulation and conformal radiotherapy planning and treatment in both positions. The clinical target volume encompassed the prostate gland. Alternate day lateral port films were compared to corresponding simulator radiographs to measure the isocentre positioning errors (IPE). Prostate motion (PM) and total positioning error (TPE) were measured from the same films by the displacements of three implanted fiducial markers. Dose volume histograms (DVHs) for the two treatment positions were compared at the 95, 80 and 50% dose (D%) levels. The patients and radiation therapists completed weekly questionnaires regarding patient comfort and ease of setup.

RESULTS

Seven patients, who started in the supine position, subsequently refused prone position and received their whole treatment supine. Small bowel in the treatment volume, not present in the supine position, prevented one patient from being treated prone. PM in anterior posterior direction was statistically significantly less in the supine position (P<0.05). There was no significant difference in superior inferior PM for the two treatment positions. No statistically significant difference between supine and prone positioning was observed in isocentre positioning error (IPE) or total positioning error (TPE) due to a policy of daily pre-treatment correction. However, more pre-treatment corrections were required for patients in the prone position. The DVH analysis demonstrated larger volumes of the bladder wall, rectal wall and small bowel within the D95, D80 and D50% when comparing the planning target volumes (PTVs) actually treated for prone positioning. When the prone PTV was expanded to account for the greater PM encountered in that position, a statistically significant difference (P<0.007) was observed in favour of the supine position at all dose levels. In the prone position, four patients had small bowel within the 60 Gray (Gy) isodose and in the supine position, no patients had small bowel in the 60 or 38Gy volumes. Supine position was significantly more comfortable for the patients and setup was significantly easier for the radiation therapists. The median patient comfort score was 0.79 (Standard deviation (SD) 0.03) supine and 0.45 (SD 0.05) prone (P<0.001) The therapist convenience of setup was 0.80 (SD 0.016) supine and 0.54 (SD 0.025) prone (P<0.005). No statistically significant difference was seen for the other parameters studied.

CONCLUSIONS

We demonstrated significantly less PM in the supine treatment position. There was no difference for either treatment position in IPE or TPE, however, more pre-treatment corrections were required in the prone position. Prone position required a larger PTV with resulting increased dose to critical organs. There were statistically significant improvements at all dose levels for small bowel, rectal wall and bladder wall doses in the supine position once corrections were made for differences in organ motion. Linear analogue scores of patient comfort and radiation therapist convenience demonstrated statistically significant improvement in favour of the supine position. Supine positioning has been adopted as the standard for conformal prostatic irradiation at our centre.

Patient setup error measurement using 3D intensity-based image registration techniques

PURPOSE

Conformal radiotherapy requires accurate patient positioning with reference to the initial three-dimensional (3D) CT image. Patient setup is controlled by comparison with portal images acquired immediately before patient treatment. Several automatic methods have been proposed, generally based on segmentation procedures. However, portal images are of very low contrast, leading to segmentation inaccuracies. In this study, we propose an intensity-based (with no segmentation), fully automatic, 3D method, associating two portal images and a 3D CT scan to estimate patient setup.

MATERIALS AND METHODS

Images of an anthropomorphic phantom were used. A CT scan of the pelvic area was first acquired, then the phantom was installed in seven positions. The process is a 3D optimization of a similarity measure in the space of rigid transformations. To avoid time-consuming digitally reconstructed radiograph generation at each iteration, we used two-dimensional transformations and two sets of specific and pregenerated digitally reconstructed radiographs. We also propose a technique for computing intensity-based similarity measures between several couples of images. A correlation coefficient, chi-square, mutual information, and correlation ratio were used.

RESULTS

The best results were obtained with the correlation ratio. The median root mean square error was 2.0 mm for the seven positions tested and was, respectively, 3.6, 4.4, and 5.1 for correlation coefficient, chi-square, and mutual information.

CONCLUSIONS

Full 3D analysis of setup errors is feasible without any segmentation step. It is fast and accurate and could therefore be used before each treatment session. The method presents three main advantages for clinical implementation-it is fully automatic, applicable to all tumor sites, and requires no additional device.

[Target-volume and critical-organ delineation for conformal radiotherapy of prostate cancer: experience of French dose-escalation trials]

The delineation of target volume and organs at risk depends on the organs definition, and on the modalities for the CT-scan acquisition. Inter-observer variability in the delineation may be large, especially when patient's anatomy is unusual. During the two french multicentric studies of conformal radiotherapy for localized prostate cancer, it was made an effort to harmonize the delineation of the target volumes and organs at risk. Two cases were proposed for delineation during two workshops. In the first case, the mean prostate volume was 46.5 mL (extreme: 31.7-61.3), the mean prostate and seminal vesicles volume was 74.7 mL (extreme: 59.6-80.3), the rectal and bladder walls varied respectively in proportion from 1 to 1.45 and from 1 to 1.16; in the second case, the mean prostate volume was 53.1 mL (extreme: 40.8-73.1), the volume of prostate plus seminal vesicles was 65.1 mL (extreme: 53.2-89), the rectal wall varied proportionally from 1 to 1, 24 and the vesical wall varied from 1 to 1.67. For participating centers to the french studies of dose escalation, a quality control of contours was performed to decrease the inter-observer variability. The ways to reduce the discrepancies of volumes delineation, between different observers, are discussed. A better quality of the CT images, use of urethral opacification, and consensual definition of clinical target volumes and organs at risk may contribute to that improvement.

The use of a leg holder immobilisation device in 3D-conformal radiation therapy of prostate cancer

BACKGROUND AND PURPOSE

To evaluate the impact of a leg holder immobilisation device on patient positioning accuracy in the treatment of prostate cancer.

MATERIAL AND METHODS

Twenty patients of similar age and stage of disease treated with curative external beam radiotherapy for prostate cancer were included prospectively. Ten patients were sequentially allocated to one of the two groups, and treated either with or without a leg holder. Treatment set-up alignment accuracy was assessed with an electronic portal imaging device (EPID).

RESULTS

Set-up accuracy was 0.3, 0.3 and 0.2 cm for patients with a leg holder, and 0.3, 0.4 and 0.2 cm for patients without a leg holder in the cranio-caudal, anterior-posterior and in the lateral positions, respectively. The difference is not significant. The repositioning accuracy of combined (sagittal and lateral) in-plane rotations on the other hand, was significantly improved with a leg holder device (P = 0.04).

CONCLUSIONS

Set-up accuracy can be improved using a leg holder immobilisation device in terms of rotational movement accuracy, thus making on-line corrections more accurate using EPID in the treatment of prostate cancer.

[Conformal radiotherapy in prostate cancer: for whom and how?]

External radiotherapy is one of the modalities used to cure localized prostate carcinoma. Most of localized prostate carcinomas, specially those of the intermediate prognostic group, may benefit from escalated dose above 70 Gy at least as regard biochemical and clinical relapse free survival. 3D-CRT allows a reduction of the dose received by organs at risk and an increase of prostate dose over 70 Gy. It is on the way to become a standard. Intensity modulated radiation therapy increases dose homogeneity and reduces rectal dose. These methods necessitate rigorous procedures in reproducibility, delineation of volumes, dosimetry, daily treatment. They need also technological and human means. It is clear that localized prostate cancer is a good example for evaluation of these new radiotherapy modalities.

Conformal photon-beam radiotherapy of prostate carcinoma

Three-dimensional conformal radiotherapy is the recommended radiation technique for localized or locally advanced prostate cancer. In the past decades, external beam irradiation procedures have evolved in the context of technical developments of radiation and imaging equipment. The article summarizes these developments and gives a definition of new techniques and their potential advantages over conventional irradiation. It is meant to provide urologists and medical and radiation oncologists with a better comprehension of modern radiation treatment of prostate cancer and its possible improvements in the future.

Effectiveness of couch height-based patient set-up and an off-line correction protocol in prostate cancer radiotherapy

PURPOSE

To investigate set-up improvement caused by applying a couch height-based patient set-up method in combination with a technologist-driven off-line correction protocol in nonimmobilized radiotherapy of prostate patients.

METHODS AND MATERIALS

A three-dimensional shrinking action level correction protocol is applied in two consecutive patient cohorts with different set-up methods: the traditional "laser set-up" group (n = 43) and the "couch height set-up" group (n = 112). For all directions, left-right, ventro-dorsal, and cranio-caudal, random and systematic set-up deviations were measured.

RESULTS

The couch height set-up method improves the patient positioning compared to the laser set-up method. Without application of the correction protocol, both systematic and random errors reduced to 2.2-2.4 mm (1 SD) and 1.7-2.2 mm (1 SD), respectively. By using the correction protocol, systematic errors reduced further to 1.3-1.6 mm (1 SD). One-dimensional deviations were within 5 mm for >90% of the measured fractions. The required number of corrections per patient in the off-line correction protocol was reduced significantly during the course of treatment from 1.1 to 0.6 by the couch height set-up method. The treatment time was not prolonged by application of the correction protocol.

CONCLUSIONS

The couch height set-up method improves the set-up significantly, especially in the ventro-dorsal direction. Combination of this set-up method with an off-line correction strategy, executed by technologists, reduces the number of set-up corrections required.