Image-guided Radiotherapy For Prostate Cancer Research Articles

Interfractional Seminal Vesicle Motion Relative to the Prostate Gland for Image-guided Radiotherapy for Prostate Cancer with/without Androgen Deprivation Therapy: A Retrospective Cohort Study.

We investigated differences in seminal vesicle (SV) length and interfractional SV motion relative to the prostate gland in prostate cancer patients. We compared 32 patients who received androgen deprivation therapy (ADT) before radiotherapy with 12 patients receiving radiotherapy alone at Okayama University Hospital in August 2008-July 2011. We examined the right and left SVs' length and motion by computed tomography (CT) to determine the ADT's effects and analyzed 347 CT scans in a multiple linear regression model. The ADT patients' SV length was significantly shorter than the non-ADT patients'. The differences in right and left SV lengths between the ADT and non-ADT patients were 6.8 mm (95% CI 2.0-11.7 mm) and 7.2 mm (95% CI 3.1- 11.3 mm) respectively in an adjusted regression model. SV motion did not differ between the ADT and non- ADT patients in terms of interfractional motion of the SV tips and the SVs' center relative to the prostate gland. The ADT patients had significantly shorter SVs compared to the non-ADT patients, but no difference in SV motion was observed. SV interfractional motion should thus be compensated using the same planning margins, regardless of whether ADT is used.

Image-guided radiotherapy for prostate cancer in the United Kingdom: a national survey.

To survey the technology and practice of image-guided radiotherapy (IGRT) for prostate cancer in the UK. A pre-tested semi-structured online questionnaire was sent to National Health Service (NHS) and private radiotherapy providers in the UK between March and April 2014. The survey was carried out on the Opinio© online platform. There was a high survey response rate of 83%. There is widespread use of intensity-modulated radiotherapy and advanced verification imaging modalities. Cone-beam CT (CBCT) is the main verification imaging modality in radical prostate radiotherapy, used in 66% of UK centres. Fiducial markers in combination with imaging were used in 30% of centres. Over half the centres used a daily imaging schedule, with a Day 1-3 frequency followed by weekly frequency used less commonly. 26% of centres used daily CBCT. There is widespread use of volumetric verification imaging with CBCT for prostate radiotherapy in the UK. There is no consensus on the optimal verification imaging schedule. Advances in knowledge: This survey provides an insight into contemporary UK practice of IGRT for prostate cancer, both in the NHS and private sector. It demonstrates the widespread use of CBCT imaging and highlights the need for further research to optimize the practice.

Three-dimensional surface and ultrasound imaging for daily IGRT of prostate cancer.

BackgroundImage guided radiotherapy (IGRT) is an essential pre-requisite for delivering high precision radiotherapy. We compared daily variation detected by two non-ionizing imaging modalities (surface imaging and trans-abdominal ultrasound, US) to verify prostate patient setup and internal organ variations.MethodsForty patients with organ confined prostate cancer and candidates to curative radiotherapy were enrolled in this prospective study. At each treatment session, after laser alignment, all patients received imaging by a 3D-surface and a 3D-US system. The shifts along the three directions (anterior-posterior AP, cranial-caudal CC, and later-lateral LL) were measured in terms of systematic and random errors. Then, we performed statistical analysis on the differences and the possible correlations between the two modalities.ResultsFor both IGRT modalities, surface imaging and US, 1318 acquisitions were collected. According with Shapiro Wilk test, the positioning error distributions were not Gaussian for both modalities.The differences between the systematic errors detected by the two modalities were statistically significant only in LL direction (p < 0.05), while the differences between the random errors were not statistically significant in any directions.The 95% confidence interval of the residual errors obtained by subtracting the random errors detected with surface images to those detected with US was included in the range from −7 mm to 7 mm corresponding to the minimum PTV margin adopted in AP direction in our clinical routine.ConclusionsFrom our data, it emerges that setup misalignments measured by surface imaging can be predictive of US displacements after the adjustment for systematic errors. Moreover, surface imaging can detect setup errors predictive of registration errors measured by US. This data suggest that the two IGRT modalities could be considered as complementary to each other and could represent a daily “low-cost” and non-invasive IGRT modality in prostate cancer patients.

Image-guided radiotherapy for prostate cancer with cone beam CT: dosimetric effects of imaging frequency and PTV margin

Background and purposeThis study assesses the effect of frequency of cone beam CT (CBCT) verification imaging on dose–volume parameters during image-guided radiotherapy (IGRT) for prostate cancer. It also investigates the dosimetric impact of reducing the planning target volume (PTV) margin, when daily imaging is used. Material and methods844 CBCT images from 20 patients undergoing radical prostate radiotherapy were included. Patients received a dose of 74Gy in 37 fractions using 7-field intensity-modulated radiotherapy (IMRT). Clinical target volume (CTV) and organs at risk were contoured manually on each slice of every CBCT image. A daily online CBCT verification schedule was compared with a protocol of verification on days 1–3 followed by weekly online imaging. PTV margins of 3mm, 5mm, and 7mm were compared for the daily imaging protocol. Results90% of patients had improved target coverage with daily online in comparison to weekly online imaging. A median of 37 fractions per treatment course achieved CTV coverage with daily imaging compared to 34 fractions with a weekly online protocol. 80% of patients had a reduction in rectal dose with the daily protocol. PTV margin reduction to 5mm with adequate target coverage was feasible with daily imaging. ConclusionsDaily online CBCT verification improves CTV coverage and reduces rectal dose during IGRT for prostate cancer. Tighter PTV margins could be considered with daily CBCT use.

EP-1231: Comparison of cone beam CT imaging protocols in imageguided radiotherapy for prostate cancer

EP-1231: Comparison of cone beam CT imaging protocols in imageguided radiotherapy for prostate cancer

Fiducial Marker Insertion for Image-guided Radiotherapy for Prostate Cancer: What is the Infection Rate and can Targeted Antibiotic Prophylaxis Reduce this?

Fiducial Marker Insertion for Image-guided Radiotherapy for Prostate Cancer: What is the Infection Rate and can Targeted Antibiotic Prophylaxis Reduce this?

Five-year follow-up using a prostate stent as fiducial in image-guided radiotherapy of prostate cancer

Purpose. To report results from the five-year follow-up on a previously reported study using image-guided radiotherapy (IGRT) of localized or locally advanced prostate cancer (PC) and a removable prostate stent as fiducial.Material and methods. Patients with local or locally advanced PC were treated using five-field 3D conformal radiotherapy (3DRT). The clinical target volumes (CTV) were treated to 78 Gy in 39 fractions using daily on-line image guidance (IG). Late genito-urinary (GU) and gastro-intestinal (GI) toxicities were scored using the radiotherapy oncology group (RTOG) score and the common toxicity score of adverse events (CTC) score. Urinary symptoms were also scored using the international prostate symptom score (IPSS).Results. Median observation time was 5.4 year. Sixty-two of the 90 patients from the original study cohort were eligible for toxicity assessment. Overall survival, cancer-specific survival and biochemical freedom from failure were 85%, 96% and 80%, respectively at five years after radiotherapy. Late toxicity GU and GI RTOG scores ≥ 2 were 5% and 0%. Comparing pre- and post-radiotherapy IPSS scores indicate that development in urinary symptoms after radiotherapy may be complex.Conclusions. Prostate image-guided radiotherapy using a prostate stent demonstrated survival data comparable with recently published data. GU and GI toxicities at five-year follow-up were low and comparable to the lowest toxicity rates reported. These findings support that the precision of the prostate stent technique is at least as good as other techniques. IPSS revealed a complex development in urinary symptoms after radiotherapy.

Fiducial marker implantation in prostate radiation therapy: Complication rates and technique

PurposeThis study aims to report the complication rate from the transrectal ultrasound-guided implantation of gold seed markers in prostate radiotherapy, as well as describing the technique used. Materials and methodsBetween May 2010 and December 2012, 169 patients with localized prostate cancer had an intraprostatic fiducial marker implantation under transrectal ultrasound guidance. The procedure included prophylactic antibiotic therapy, fleet enema, implantation performed by trained radiation oncologists at our center prior to image-guided radiotherapy. Toxicity occurring between implantation and subsequent radiotherapy start date was assessed. The following parameters were analyzed via medical chart review: antibiotic therapy, anticoagulant interruption, bleeding, pain, prostate volume, number of markers implanted, post-implantation complications and delay before starting radiotherapy. ResultsOf the 169 men, 119 (70.4%) underwent insertion of 4 fiducial markers and the other 50 (29.6%) had 3. The procedure was well-tolerated. There was no interruption of the implantation with regards to pain or hemorrhage. No grade 3 or 4 complications were observed. Seed migration rate was 0.32%, for the migration of 2 markers on 626 implanted. Mean prostate volume was 38cm3 (range: 10–150cm3). Two patients (1.18%) developed a urinary tract infection following the procedure: prostate volume of 25 and 65cm3, four gold seed markers implanted, urinary tract infection resistant to prophylactic antibiotherapy, and treated with antibiotics specific to their infection as determined on urine culture. ConclusionTransrectal fiducial marker implantation for image-guided radiotherapy in prostate cancer is a well-tolerated procedure without major associated complications.

Impact of planning target volume margins and rectal distention on biochemical failure in image-guided radiotherapy of prostate cancer

Background and purposeA previous study in our department demonstrated the negative impact on freedom from biochemical failure (FFBF) of using too narrow planning target volume (PTV) margins during prostate image-guided radiotherapy (IGRT). Here, we investigated the impact of appropriate PTV margins and rectal distention on FFBF. Methods and materialsA total of 50 T1-T3N0M0 prostate cancer patients were treated with daily IGRT by implanted markers. In the first 25 patients, PTV margins were 3mm laterolateral, 5mm anterioposterior and 4mm craniocaudal. The subsequent 25 patients were treated with isotropic margins of 6mm. The rectal cross-sectional area (CSA) was determined on the planning CT. Median follow-up was 61months. ResultsThe overall 5-year FFBF was 83%. A 6mm PTV margin was related to increased 5-year FFBF on univariate analysis (96% vs 74% with the tighter PTV margins, p=0.04). The 5-year FFBF of patients with a rectal distention on the planning CT was worse compared to those with limited rectal filling (75% for CSA⩾9cm2 vs 89% for CSA<9cm2, p=0.02), which remained significant on multivariate analysis (p=0.04). ConclusionThis retrospective study illustrated the positive impact of PTV margin adaptation and addressed the importance of avoiding rectal distention at time of the planning CT.

Extreme Hypofractionated Image-Guided Radiotherapy for Prostate Cancer

An emerging body of data suggests that hypofractionated radiation schedules, where a higher dose per fraction is delivered in a smaller number of sessions, may be superior to conventional fractionation schemes in terms of both tumour control and toxicity profile in the management of adenocarcinoma of the prostate. However, the optimal hypofractionation scheme is still the subject of scientific debate. Modern computer-driven technology enables the safe implementation of extreme hypofractionation (often referred to as stereotactic body radiation therapy [SBRT]). Several studies are currently being conducted to clarify the yet unresolved issues regarding treatment techniques and fractionation regimens. Recently, the American Society for Radiation Oncology (ASTRO) issued a model policy indicating that data supporting the use of SBRT for prostate cancer have matured to a point where SBRT could be considered an appropriate alternative for select patients with low-to-intermediate risk disease. The present article reviews some of the currently available data and examines the impact of tracking technology to mitigate intra-fraction target motion, thus, potentially further improving the clinical outcomes of extreme hypofractionated radiation therapy in appropriately selected prostate cancer patients. The Champalimaud Centre for the Unknown (CCU)’s currently ongoing Phase I feasibility study is described; it delivers 45 Gy in five fractions using prostate fixation via a rectal balloon, and urethral sparing via catheter placement with on-line intra-fractional motion tracking through beacon transponder technology.

The Risk of Urosepsis in Patients Undergoing Fiducial Marker Placement for Image Guided Radiation Therapy (IGRT) of Prostate Cancer

To determine the risk of urosepsis after the placement of intraprostatic soft tissue fiducial markers used for IGRT for prostate cancer. Between June 2008 and December 2012, 3851 patients underwent fiducial-based kV (stereoscopic or CBCT) prostate IGRT for prostate cancer at our institution and serve as the population base for this study. Two gold soft-tissue markers (1 cm Visicoil) were implanted into the prostate by the Radiation Oncologist or Urologist using transrectal ultrasound via an 18 gauge pre-loaded needle in the right and left peripheral lobes of the prostate. All patients received prophylactic antibiotics prior to and after the procedure. Additional prep included temporary discontinuation of anticoagulants and typically a commercially available enema such as Fleets prior to the procedure to clear the rectal vault. Beginning in 2009, as part of our ongoing quality management processes, we instituted a standardized antibiotic prophylaxis regimen based on regional antibiogram which included double antibiotics, a mechanical double enema prep (night before and day of procedure instead of day of only), and a one hour delay between the procedure and any intramuscular injection of an antibiotic. Data was collected both on an on-going basis, as well as via a query of Radiation Oncology and Urology Electronic Medical Records (cross-referencing fiducial marker placement codes with subsequent sepsis hospitalization or treatment, with confirmation of generated data via hospital record review and/or direct patient and physician contact. A total of 7702 fiducials were inserted in 3851 patients for fiducial-based kV prostate IGRT. Of those, 31 patients developed urosepsis attributable to the placement of fiducial markers yielding a urosepsis rate of 0.8% per patient or 0.4% per marker placed. The number of cases of urosepsis fell over time with 65% (20/31), 22% (7/31), 6% (2/31), and 6% (2/31) of the cases occurring in 2008-2009, 2010, 2011, and 2012, respectively. Although the rate of urosepsis was only 0.8% overall, this rate significantly decreased by 2011 and remained low in 2012. Based on one of the largest cohorts of patients undergoing fiducial-based kV IGRT for prostate cancer, the risk of urosepsis due to implantation of soft-tissue fiducial markers for IGRT is extremely low. The routine use of double antibiotic prophylaxis, double enema (night before and day of procedure instead of day of only), and a one hour delay between the procedure and intramuscular injection of an antibiotic has decreased the incidence of urosepsis following fiducial marker placement. This decline in the sepsis rate is directly attributable to our institution's quality management measures which allowed for the standardization of the regimen prior to fiducial placement.

MR‐CT registration using a Ni‐Ti prostate stent in image‐guided radiotherapy of prostate cancer

In image-guided radiotherapy of prostate cancer defining the clinical target volume often relies on magnetic resonance (MR). The task of transferring the clinical target volume from MR to standard planning computed tomography (CT) is not trivial due to prostate mobility. In this paper, an automatic local registration approach is proposed based on a newly developed removable Ni-Ti prostate stent. The registration uses the voxel similarity measure mutual information in a two-step approach where the pelvic bones are used to establish an initial registration for the local registration. In a phantom study, the accuracy was measured to 0.97 mm and visual inspection showed accurate registration of all 30 data sets. The consistency of the registration was examined where translation and rotation displacements yield a rotation error of 0.41° ± 0.45° and a translation error of 1.67 ± 2.24 mm. This study demonstrated the feasibility for an automatic local MR-CT registration using the prostate stent.

EP-1079: Image-guided radiotherapy in prostate cancer: preliminary experience with kV CBCT

EP-1079: Image-guided radiotherapy in prostate cancer: preliminary experience with kV CBCT

The Value of Repeat Cone Beam CT Scans in Image Guided Radiation Therapy for Prostate Cancer

The Value of Repeat Cone Beam CT Scans in Image Guided Radiation Therapy for Prostate Cancer

Cost Minimisation Analysis: Kilovoltage Imaging with Automated Repositioning Versus Electronic Portal Imaging in Image-guided Radiotherapy for Prostate Cancer

AimsTo compare the treatment time and cost of prostate cancer fiducial marker image-guided radiotherapy (IGRT) using orthogonal kilovoltage imaging (KVI) and automated couch shifts and orthogonal electronic portal imaging (EPI) and manual couch shifts. Materials and methodsIGRT treatment delivery times were recorded automatically on either unit. Costing was calculated from real costs derived from the implementation of a new radiotherapy centre. To derive cost per minute for EPI and KVI units the total annual setting up and running costs were divided by the total annual working time. The cost per IGRT fraction was calculated by multiplying the cost per minute by the duration of treatment. A sensitivity analysis was conducted to test the robustness of our analysis. Treatment times without couch shift were compared. ResultsTime data were analysed for 8648 fractions, 6057 from KVI treatment and 2591 from EPI treatment from a total of 294 patients. The median time for KVI treatment was 6.0 min (interquartile range 5.1–7.4 min) and for EPI treatment it was 10.0 min (interquartile range 8.3–11.8 min) (P value < 0.0001). The cost per fraction for KVI was A$258.79 and for EPI was A$345.50. The cost saving per fraction for KVI varied between A$66.09 and A$101.64 by sensitivity analysis. In patients where no couch shift was made, the median treatment delivery time for EPI was 8.8 min and for KVI was 5.1 min. ConclusionsTreatment time is less on KVI units compared with EPI units. This is probably due to automation of couch shift and faster evaluation of imaging on KVI units. Annual running costs greatly outweigh initial setting up costs and therefore the cost per fraction was less with KVI, despite higher initial costs. The selection of appropriate IGRT equipment can make IGRT practical within radiotherapy departments.

The impact of image-guided radiotherapy (IGRT) for prostate cancer (PC) on radiotherapy (RT)-related acute toxicities and prostate-specific antigen (PSA) kinetics.

e15110 Background: IGRT for PC could potentially improve the therapeutic ratio by enhancing accuracy of delivery of radiation to the prostate gland. Our aim is to compare the treatment outcomes in terms of RT-related acute toxicities and PSA kinetics of PC patients (pts) undergoing radical intensity-modulated radiotherapy (IMRT) with or without image-guidance. Methods: A cohort of 21 consecutive pts treated by IGRT (I) from January 2010, when the IGRT system was introduced in our institution, was compared with an immediately precedent cohort of 21 pts receiving IMRT without image-guidance (Non-I). The prescription dose (76Gy in 38 fractions) and the treatment margins were the same between the 2 groups (gps). In the I gp, daily online verification and correction of treatment position was performed with reference to image registration of the daily pre-treatment on-board imaging with the corresponding digitally reconstructed radiographs, based on three-dimensional matching of three intra-prostatic fiducial markers. Androgen deprivation therapy was not used in both gps. Acute toxicities were scored weekly during the course of RT according to the Common Terminology Criteria for Adverse Events Version 4.02. The pre- and the post-RT PSA within 6 months after completion of RT were obtained. The PSA halving time (PSAHT) was calculated by first order kinetics. Results: There was no statistically significant difference regarding the baseline clinical characteristics (age, PSA at diagnosis, Gleason score, T staging) between the gps. No grade 3 or 4 acute genitourinary (GU) or gastrointestinal (GI) toxicities was encountered in either gps. Acute grade 1 or 2 GI toxicities were significantly less frequent in the I gp (23.8% vs 81.0%, p=0.001), and their median duration of such toxicity were also significantly shorter (0.33 week vs 1.38 week, p=0.004).The frequencies of acute grade 1 or 2 GU toxicities were comparable between both gps (66.6% vs 81.0%, p=0.45).The I gp had a shorter median PSAHT than the non-I gp (3.36 week vs 5.49 week, p=0.09). Conclusions: IGRT is effective in reducing acute GI toxicities in treatment of PC, and may have more favorable PSA kinetics.

Impact of Computed Tomography Image Quality on Image-Guided Radiation Therapy Based on Soft Tissue Registration

In image-guided radiation therapy (IGRT), different computed tomography (CT) modalities with varying image quality are being used to correct for interfractional variations in patient set-up and anatomy changes, thereby reducing clinical target volume to the planning target volume (CTV-to-PTV) margins. We explore how CT image quality affects patient repositioning and CTV-to-PTV margins in soft tissue registration-based IGRT for prostate cancer patients. Four CT-based IGRT modalities used for prostate RT were considered in this study: MV fan beam CT (MVFBCT) (Tomotherapy), MV cone beam CT (MVCBCT) (MVision; Siemens), kV fan beam CT (kVFBCT) (CTVision, Siemens), and kV cone beam CT (kVCBCT) (Synergy; Elekta). Daily shifts were determined by manual registration to achieve the best soft tissue agreement. Effect of image quality on patient repositioning was determined by statistical analysis of daily shifts for 136 patients (34 per modality). Inter- and intraobserver variability of soft tissue registration was evaluated based on the registration of a representative scan for each CT modality with its corresponding planning scan. Superior image quality with the kVFBCT resulted in reduced uncertainty in soft tissue registration during IGRT compared with other image modalities for IGRT. The largest interobserver variations of soft tissue registration were 1.1 mm, 2.5 mm, 2.6 mm, and 3.2 mm for kVFBCT, kVCBCT, MVFBCT, and MVCBCT, respectively. Image quality adversely affects the reproducibility of soft tissue-based registration for IGRT and necessitates a careful consideration of residual uncertainties in determining different CTV-to-PTV margins for IGRT using different image modalities.

Patient-reported complications from fiducial marker implantation for prostate image-guided radiotherapy

To report on complications from transrectal ultrasound-guided insertion of fiducial markers for prostate image-guided radiotherapy. 234 patients who underwent transrectal fiducial marker insertion for prostate cancer image-guided radiotherapy were assessed retrospectively by questionnaire with regard to the duration and severity of eight symptoms experienced following the procedure. Pain during the implantation procedure was assessed according to the Wong-Baker faces pain scale. Of 234 patients, 32% had at least one new symptom after the procedure. The commonest new symptom following the procedure was urinary frequency affecting 16% of patients who had not been troubled by frequency beforehand. Haematuria, rectal bleeding, dysuria and haematospermia affected 9-13% of patients, mostly at Grade 1 or 2. Pain, obstruction, and fever and shivers affected 3-4% of patients. Grade 3 rectal bleeding, haematuria, fever and shivers, and urinary frequency affected 0.5-1.5% of patients. Only one patient had a Grade 4 complication (i.e. fever and shivers). Overall, 9% of patients had symptoms lasting more than 2 weeks. The commonest symptoms that lasted more than 2 weeks were frequency, dysuria, obstructive symptoms and rectal bleeding. Mean pain score during the procedure was 1.1 (range 0-5). Transrectal ultrasound-guided fiducial marker insertion for image-guided radiotherapy is well tolerated in the majority of prostate cancer patients. Most symptoms were Grade 1 or 2 in severity. Symptoms in the majority of patients last under 2 weeks. The most serious complication was sepsis in our study.

Inverse Relationship Between Biochemical Outcome and Acute Toxicity After Image-Guided Radiotherapy for Prostate Cancer

Prostate cancer patients exhibit variability in normal tissue reactions and biochemical failure. With the use of image-guided radiotherapy (IGRT), there is a greater likelihood that the differences in normal tissue and tumor response are due to biological rather than physical factors. We tested the hypothesis that prospectively scored acute toxicity is associated with biochemical failure-free rate (BFFR) in prostate cancer patients treated with IGRT. We retrospectively analyzed BFFR in 362 patients with localized prostate cancer treated with IGRT. We compared BFFR with prospectively collected Radiation Therapy Oncology Group (RTOG) maximum acute gastrointestinal (GI) and genitourinary (GU) toxicity scores. Median follow-up for all patients was 58.3 months after total radiotherapy doses of 75.6-79.8 Gy. Patients reporting RTOG acute GU or GI toxicity scores of ≥ 2 were considered "sensitive" (n = 141, 39%) and patients reporting scores <2 were considered "nonsensitive" (n = 221, 61%). When calculating biochemical failure (BF) using the American Society for Therapeutic Radiology and Oncology definition at 5 years, 76% (CI 70-82%) of the "nonsensitive" patients were failure free, compared with only 53% (CI 43-62%) of the "sensitive" patients (log-rank test, p < 0.0001). This difference was also observed using the Phoenix definition; "nonsensitive" 5-year BFFR was 81% (CI 74-86%) vs. "sensitive" BFFR was 68% (CI 58-76%; log-rank test p = 0.0012). The difference in BF between cohorts remained significant when controlled for radiation dose (75.6 vs. 79.8 Gy), prognostic stratification (T category, prostate-specific antigen, and Gleason score), and prostate volume. This study unexpectedly shows that prostate cancer patients who develop ≥ Grade 2 RTOG acute toxicity during radiotherapy are less likely to remain BFF at 5 years. These results deserve further study and, if validated in other large IGRT cohorts, additional models would be required to study interaction between normal tissue and tumor biology in prostate cancer patients.

Fiducial registration error as a statistical process control metric in image-guidance radiotherapy with fiducial markers

Portal imaging of implanted fiducial markers has been in use for image-guided radiotherapy (IGRT) of prostate cancer, with ample attention to localization accuracy and organ motion. The geometric uncertainties in point-based rigid-body matching algorithms during localization of prostate fiducial markers can be quantified in terms of a fiducial registration error (FRE). In this study, the aim is to demonstrate how statistical process control (SPC) can be used to intercept potential problems with rigid-body matching algorithms in a retrospective study of FRE for a pilot cohort of 34 patients with fiducial markers. A procedure for estimating control parameters of a SPC control chart (x-chart) from a small number of initial observations (N) of FRE was implemented. The sensitivity analysis of N on the number of ‘in-control’ and ‘out-of-control’ x-charts was also performed. Uncorrected rotational offsets of an individual patient were examined to elucidate possible correlations with the behaviours of an x-chart. Four specific types of qualitative x-chart behaviour have been observed. The number of out-of-control processes was insensitive to the choice of N, provided N ⩾ 5. Residual errors of rigid-body registration were contributed from uncorrected rotational offsets in 5 out of 15 ‘out-of-control’ x-charts. Out-of-control x-charts were also shown to be correlated with potential changes in the IGRT processes, which may compromise the quality of the radiation treatment delivery. The SPC methodology, implemented in the form of individually customized x-charts, has been shown to be a useful tool for monitoring process reliability during fiducial-based IGRT for prostate cancer.