All, Forgive me I am a newbie in the DICOM world. I tried to learn the DCMTk tools to talk with PACS server. But didn't found much tutorial or sample in the internet to know enough about it .Currently I just have the offical document to read.
I just tried the findscu.exe to test c-find command .
I remembered C-Find would return what specified in the request message. for example. If I only specifed the condition Patient Name ='abc' then the reponse would return only attribute Patient Name. Nothing else.( If it is not right . Please correct me.)
So I want to know how to return all the attribute of response DICOM.
Thanks.
How to specified multiple attributes in the findscu command.
Just specify multiple --key (-k) options on the command line. Alternatively, you could also use a "query file" as described in the man page.
So I want to know how to return all the attribute of response DICOM.
Then, you have to specify all attributes (keys) you are interested in. That's how C-FIND works.
By the way, if you are querying a PACS (Query/Retrieve SCP), then you also have to specify the Query/Retrieve Level (0008,0052), e.g. "PATIENT".
Currently I just have the offical document to read.
If you think that the examples in the man page of the findscu tool are not sufficient (and you are actually querying a PACS), this HOWTO might be useful too.
It is totally legal to send a request with Patient Name information only and the PACS will return all matching datasets.
Each dataset should at least contain all mandatory fields like Date of Birth, Patient ID, and so on, depending on the Query Level.
What information is returned by the PACS system on each Query Level should be specified in the DICOM Conformance Statement of the vendor. I would recommend to take a look at this to know, how to set up a valid query to get the information you need and/or if the information is provided by the PACS system.
It is best to include the Unique key and Required Key Attributes in the request attribute list. Also, include the optional attributes (if supported by SCP) when you wish server to return values for them. Please refer to DICOM Standard PS 3.4 section C.2 and C.3 detail information on Query/Retrieve service. List of attribute and type (Unique, Required, Optional) is listed section C.6.1.1.2 (Patient Level), C.6.1.1.3 (Study Level) and so on.
Related
I need to create a Secondary Capture Image representing a report related to radiopharmaceutical and dose injected to the patient during the medical examination.
I know Secondary Capture Image is not the right choice to accomplish the task but that is what the customer requires.
Following are the steps I thought to implement for developing the feature and I would like to read some opinions or suggestion from the community.
Assumption: MWL is implemented and the Study Instance UID is generated in the RIS
query the MWL (C-FIND) to get the requested procedure object
parse the result to get the StudyInstanceUID and patient related
informations (name, sex, birthdate etc.)
query (C –FIND) the modality looking for the specific Study
Instance UID
parse the result to get the Series Instance UID
create the image setting the three mandatory attribute Study
Instance UID, Series Instance UID, Modality (together with some type
2 attributes I got querying MWL and modality in the previous
steps)
C-STORE to persist the image to the storage archive
Commit of the image (do I really need?)
I really appreciate comments opinions or someone that can address me to a more solid architecture.
correct
correct. Do not forget about attributes that are not so obvious like Admission ID, Accession Number, Referring Physicians Name and others.
The majority of modalities does not support Query/Retrieve as an SCP. If you would really need to query for the images, send the C-FIND to the PACS rather than the modality. The Study Instance UID comes with the worklist. Even if the UID you find by Query differs from that, I would strongly recommend to use the one from the worklist. However, I do not see any sense in using attributes from other sources than the MWL and your own "acquisition".
Why would you want to add the image to an existing series? It would probably be more appropriate to create a new one. There are a lot of reasons for that, e.g. Modality and vendor/equipment information are series level information and probably different.
There are more mandatory attributes for SC (e.g. in the general image module). Not all come from the MWL.
yes.
You do not have to. However, suppose that your images are lost:
a) you have received a storage commitment from the PACS -> blame on the PACS
b) you have not received a storage commitment from the PACS -> blame on ...? ;-)
When i have a resource, let's say customers/3 which returns the customer object and i want to return this object with different fields, or some other changes (for example let's say i need to have include in customer object also his latest purchase (for the sake of speed i dont want to do 2 different queries)).
As i see it my options are:
customers/3/with-latest-purchase
customers/3?display=with-latest-purchase
In the first option there is distinct URI for the new representation, but is this REALLY needed? Also how do i tell the client that this URI exist?
In the second option there is GET parameter telling the server what kind of representation to return. The URI parameters can be explained through OPTIONS method and it is easier to tell client where to look for the data as all the representations are all in one place.
So my question is which of these is better (more RESTful) and/or is there some better way to do this that i do not know about?
I think what is best is to define atomic, indivisible service objects, e.g. customer and customer-latest-purchase, nice, clean, simple. Then if the client wants a customer with his latest purchases, they invoke both service calls, instead of jamming it all in one with funky parameters.
Different representations of an object is OK in Java through interfaces but I think it is a bad idea for REST because it compromises its simplicity.
There is a misconception that making query parameters look like file paths is more RESTful. The query portion of the address is included when determining a distinct URI so the second option is fine.
Is there much of a performance hit in including the latest purchase data in all customer GET requests? If not, the simplest thing would be to do that so there would neither be weird URL params or double requests. If getting the latest order is a significant hardship (which it probably shouldn't be) there is nothing wrong with adding a flag in the query string to include it.
I have come across this issue a few times now, and each time I make a fruitless search to come up with a satisfying answer.
We have a collection resource which returns a representation of the member URIs, as well as a Link header field with the same URIs (and a custom relation type). Often we find that we need specific data from each member in the collection.
At one extreme, we can have the collection return nothing but the member URIs; the client must then query each URI in turn to determine the required data from each member.
At the other extreme, we return all of the details we might want on the collection. Neither of these is perfect; the first can result in a large number of API calls, and the second may return a lot of potentially unneeded information.
Of the two extremes I favour the second in our case, since we rarely use this for more than one sutiation. However, for a more general approach, I wondered if anyone had a nice way of dynamically specifying which details should be included for each member of the collection? I guess a query string parameter would be most appropriate, but I don't want to break the self-descriptiveness of the resource.
I prefer your first option..
At one extreme, we can have the
collection return nothing but the
member URIs; the client must then
query each URI in turn to determine
the required data from each member.
If you are wanting to reduce the number of HTTP calls over the wire, for example calling a service from a handset app (iOS/Android). You can include an additional header to include the child resources:
X-Aggregate-Resources-Depth: 2
Your server side code will have to aggregate the resources to the desired depth.
Sounds like you're trying to reinvent PROPFIND (RFC 4918, Section 9.1).
I regularly contain a subset of elements in each item within a collection resource. How you define the different subsets is really up to you. Whether you do,
/mycollectionwithjustlinks
/mycollectionwithsubsetA
/mycollectionwithsubsetB
or you use query strings
/mycollection?itemfields=foo,bar,baz
either way they are all different resources. I'm not sure why you believe this is affecting the self-descriptive constraint.
I'm well into implementing a REST service (on a Windows CE platform if that matters) and I started out using IBM's general definitions of using POST for creating (INSERTs) and PUT for updating.
Now I've run across Sun's definitions which are exactly the opposite. So my question is, which is the "generally accepted" definition? Or is there even one?
The disadvantage of using PUT to create resources is that the client has to provide the
unique ID that represents the object it is creating. While it usually possible for the client
to generate this unique ID, most application designers prefer that their servers (usually
through their databases) create this ID. In most cases we want
our server to control the generation of resource IDs. So what do we do? We can switch
to using POST instead of PUT.
So:
Put = UPDATE
Post = INSERT
The reason to use POST as INSERT and PUT as UPDATE is that POST is the only nonidempotent and unsafe operation according to HTTP. Idempotent means that no matter how many times you apply the operation, the result is always the same. In SQL INSERT is the only nonidempotent operation so it should be mapped onto POST. UPDATE is idempotent so it can be mapped on PUT. It means that the same PUT/UPDATE operation may be applied more than one time but only first will change state of our system/database.
Thus using PUT for INSERT will broke HTTP semantic viz requirement that PUT operation must be idempotent.
The verbs are:
GET {path}: Retrieve the resource whose identifier is {path}.
PUT {path}: Create or update the resource whose identifier is {path}.
DELETE {path}: Delete the resource whose identifier is {path}.
POST {path}: Invoke an action which is identified by {path}.
When the intention is to create a new resource, we can use PUT if we know what the identifier of the resource should be, and we can use POST if we want the server to determine the identifier of the new resource.
PUT can be used for creation when the server grants the client control over a portion of its URI space. This is equivalent to file creation in a file system: when you save to a file that does not yet exist you create it and if that file exists the result is an update.
However, PUT is lacking the ability of an implicit intent of the client. Consider placing an order: if you PUT to /orders/my-new-order the meaning can only ever be update the resource identified by /orders/my-new-order whereas POST /orders/ can mean 'place a new order' if the POST accepting resource has the appropriate semantics.
IOW, if you want to achieve anything as a side effect of the creation of the new resource you must use POST.
Jan
We use POST= Create, PUT= Update.
Why? There's no good reason. We had to choose one, and that's that choice I made.
Edit. Looking at other answers, I realize that the key creation issue might make the decision.
We POST new entries and return a JSON object with the generated key. It seems like this is a better fit for generally accepted POST semantics.
We PUT to existing entries with a full URI that identifies the object.
Here http://www.w3.org/Protocols/rfc2616/rfc2616.html is the offical guide of how to implement the behaviour of the HTTP methods.
I've been studying the concepts and implementations of REST a lot lately and the general consensus seems to be: PUT is used for creating/updating depending on whether or not the resource already exists. POST is used to append a resource to a collection.
See HTTP/1.1 Method Definitions http://www.w3.org/Protocols/rfc2616/rfc2616-sec9.html
POST is designed to allow a uniform method to cover the following
functions:
- Annotation of existing resources;
- Posting a message to a bulletin board, newsgroup, mailing
list, or similar group of articles;
- Providing a block of data, such as the result of submitting a
form, to a data-handling process;
- Extending a database through an append operation.
The PUT method requests that the enclosed entity be stored under the
supplied Request-URI. If the Request-URI refers to an already existing
resource, the enclosed entity SHOULD be considered as a modified
version of the one residing on the origin server.
Also see the accepted answer to the question at Understanding REST: Verbs, error codes, and authentication.
I have a resource that has a counter. For the sake of example, let's call the resource profile, and the counter is the number of views for that profile.
Per the REST wiki, PUT requests should be used for resource creation or modification, and should be idempotent. That combination is fine if I'm updating, say, the profile's name, because I can issue a PUT request which sets the name to something 1000 times and the result does not change.
For these standard PUT requests, I have browsers do something like:
PUT /profiles/123?property=value&property2=value2
For incrementing a counter, one calls the url like so:
PUT /profiles/123/?counter=views
Each call will result in the counter being incremented. Technically it's an update operation but it violates idempotency.
I'm looking for guidance/best practice. Are you just doing this as a POST?
I think the right answer is to use PATCH. I didn't see anyone else recommending it should be used to atomically increment a counter, but I believe RFC 2068 says it all very well:
The PATCH method is similar to PUT except that the entity contains a
list of differences between the original version of the resource
identified by the Request-URI and the desired content of the resource
after the PATCH action has been applied. The list of differences is
in a format defined by the media type of the entity (e.g.,
"application/diff") and MUST include sufficient information to allow
the server to recreate the changes necessary to convert the original
version of the resource to the desired version.
So, to update profile 123's view count, I would:
PATCH /profiles/123 HTTP/1.1
Host: www.example.com
Content-Type: application/x-counters
views + 1
Where the x-counters media type (which I just made up) is made of multiple lines of field operator scalar tuples. views = 500 or views - 1 or views + 3 are all valid syntactically (but may be forbidden semantically).
I can understand some frowning-upon making up yet another media type, but I humbly suggest it's more correct than the POST / PUT alternative. Making up a resource for a field, complete with its own URI and especially its own details (which I don't really keep, all I have is an integer) sounds wrong and cumbersome to me. What if I have 23 different counters to maintain?
An alternative might be to add another resource to the system to track the viewings of a profile. You might call it "Viewing".
To see all Viewings of a profile:
GET /profiles/123/viewings
To add a viewing to a profile:
POST /profiles/123/viewings #here, you'd submit the details using a custom media type in the request body.
To update an existing Viewing:
PUT /viewings/815 # submit revised attributes of the Viewing in the request body using the custom media type you created.
To drill down into the details of a viewing:
GET /viewings/815
To delete a Viewing:
DELETE /viewings/815
Also, because you're asking for best-practice, be sure your RESTful system is hypertext-driven.
For the most part, there's nothing wrong with using query parameters in URIs - just don't give your clients the idea that they can manipulate them.
Instead, create a media type that embodies the concepts the parameters are trying to model. Give this media type a concise, unambiguous, and descriptive name. Then document this media type. The real problem of exposing query parameters in REST is that the practice often leads out-of-band communication, and therefore increased coupling between client and server.
Then give your system a uniform interface. For example, adding a new resource is always a POST. Updating a resource is always a PUT. Deleting is DELETE, and getiing is GET.
The hardest part about REST is understanding how media types figure into system design (it's also the part that Fielding left out of his dissertation because he ran out of time). If you want a specific example of a hypertext-driven system that uses and doucuments media types, see the Sun Cloud API.
After evaluating the previous answers I decided PATCH was inappropriate and, for my purposes, fiddling around with Content-Type for a trivial task was a violation of the KISS principle. I only needed to increment n+1 so I just did this:
PUT /profiles/123$views
++
Where ++ is the message body and is interpreted by the controller as an instruction to increment the resource by one.
I chose $ to deliminate the field/property of the resource as it is a legal sub-delimiter and, for my purposes, seemed more intuitive than / which, in my opinion, has the vibe of traversability.
I think both approaches of Yanic and Rich are interresting. A PATCH does not need to be safe or indempotent but can be in order to be more robust against concurrency. Rich's solution is certainly easier to use in a "standard" REST API.
See RFC5789:
PATCH is neither safe nor idempotent as defined by [RFC2616], Section
9.1.
A PATCH request can be issued in such a way as to be idempotent,
which also helps prevent bad outcomes from collisions between two
PATCH requests on the same resource in a similar time frame.
Collisions from multiple PATCH requests may be more dangerous than
PUT collisions because some patch formats need to operate from a
known base-point or else they will corrupt the resource.