ESTRO 36 Abstract Book

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S510 ESTRO 36 2017
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Figure 1: Difference in D90 (%) between plugged (blue)
and plug-free (pink) needles in each sector.
Conclusion
Our study suggests that plug-free needles have the
potential to improve implant quality via better spatial
dose distribution within the prostate using fewer numbers
of needles and reduced seed loss. Further, it provides
added freedom to use any number of special loaded
strands without increasing needle numbers.
PO-0928 Androgen deprivation therapy influences PSA
bounce rate after brachytherapy
W. Burchardt1, M. Kanikowski1, J. Skowronek1
1 Greater Poland Cancer Centre, Brachytherapy, Poznan,
Poland
Purpose or Objective
To evaluate predictive clinical and dosimetric factor for
PSA bounce (PB) after HDR and LDR brachytherapy with or
without androgen deprivation therapy (ADT). PB can
imitate biochemical failure and causes introduction of
unnecessary diagnostics and patients’ treatment.
Material and Methods
We analysed data of 101 patients (age 50-81 years) with
clinical localized prostate cancer (T1-T2cN0) treated with
brachytherapy from June 2008 to December 2010 at
Greater Poland Cancer Centre in Poznan, Poland.
Neoadjuvant or adjuvant androgen deprivation therapy
was applied in 33 cases. All patients underwent LDR (LDR
n=41) or HDR (HDR n=53) brachytherapy with curative
intent. The total doses (TD) for LDR was 145 Gy and for
HDR brachytherapy 3 x 10,5 - 15 Gy.
Results
A total of 94 patients were followed up at our Cancer
Centre. Median follow-up was 3,0 years. Average initial
PSA (iPSA) value was 7,8 ng/ml +/-3,1 (SD). In the follow
up the median PSA nadir 0,1 ng/ml was achieved after
median 21 months. In 58 cases PSA decreased gradually
without any event. In 23 cases PB was observed using 0,2
ng/ml definition. In 10 cases (11%) biochemical failure
(BF) was diagnosed using nadir + 2 ng/ml definition. In 24%
of patients PB was observed. Patients treated with ADT
experienced fewer PB than hormone naïve patients (90 %
vs. 62%, p=0,016). Patients with PB achieved later and
higher PSA nadir (time to nadir 30 vs. 18 months and PSA
nadir 0,3 vs. 0,1 ng/ml). Clinical stage, Gleason scale,
iPSA and risk groups were not different between PB and
No PB groups.
Conclusion
Patients after brachytherapy for low and intermediate risk
prostate cancer had PB in 24 % of cases. ADT decreased
the PB rate after brachytherapy what could have
protected the patients from unnecessary interventions.
Patients with PB had later and higher level of PSA nadir.
Other clinical and dosimetric factors were not predictive
for PB.
PO-0929 Needle Migration in HDR Brachytherapy for
Prostate Cancer evaluated by Serial MRI a nd Photos
S. Buus1, M. Lizondo2, S. Hokland3, S. Rylander3, E.
Pedersen4, L. Bentzen1, K. T anderup3
1Aarhus University Hospital, Department o f Oncology,
Aarhus C, Denmark
2Hospital de la Santa Creu i Sant Pau, Servei de
Radiofísica i Radioprotecció, Barcelona, Spain
3Aarhus University Hospital, Department of Medical
physics, Aarhus C, Denmark
4Aarhus University Hospital, Department of Radiology,
Aarhus C, Denmark
Purpose or Objective
Needle migration in high dose rate brachytherapy (HDR-
BT) for prostate cancer may lead to insufficient target
coverage and increased dose to organs at risk. The aim of
this study was to assess the magnitude of needle migration
in HDR-BT with serial MRI and photos.
Material and Methods
12 patients with high risk prostate cancer treated with
EBRT and two separate boosts of HDR-BT were included in
the study. In order to fixate the needles, a thin silicone
pad was placed within the template, which was fixated to
perineum with 4 sutures. Following US guided needle
implant, patients were placed in supine positi on on an MRI
couch on trolley for the rest of the procedure. Three MRIs
were performed; one for planning (MRI1), one
immediately before HDR-BT (MRI2), and one after HDR-BT
(MRI3). All MRIs were a transversal T2-weighted turbo
spin-echo with 2 mm slice thickness and 1.2 x 1.49 mm
resolution. The position of the template was marked with
indian ink on the thighs of patients, and photos of the
perineum were taken after each MRI. MRI2 and MRI3 were
co-registered to MRI1 to match the prostate. Coordinates
of each needle tip defined on all three MRIs were used to
calculate the migration for each needle. An average
needle migration of ≤3 mm was considered "acceptable".
On photos, movement of the template relative to the ink
markings was regarded as needle migration, which was
scored as either "acceptable" or "considerable" from MRI1
to MRI2 and from MRI1 to MRI3. Scoring of needle
migration with MRI and photos was compared. An analysis
was performed to examine whether posterior needles
were more prone to migrate compared with anterior
needles.
Results
A median of 16 needles (14 - 21) were used for each HDR-
BT procedure. Serial photos were taken in 19/24
procedures. MRI2 was performed in 24/24 procedures and
MRI3 in 22/24 procedures. MRI evaluated needle migration
was median 2.2 mm per needle (-0.8 - 4.4) from MRI1 to
MRI2, median 2.6 mm per needle (0 - 10) from MRI2 to
MRI3, and median 3.9 mm per needle (0.3 - 9.8) from MRI1
to MRI3. Needle migration evaluated by MRI was found
"acceptable" in 23/24 procedures from MRI1 to MRI2, and
in 7/22 procedures measured from MRI1to MRI3. Needle
migration evaluated by photo was found "acceptable" in